F75 stainless steel special-shaped part and sintering method thereof

Abstract

The invention provides an F75 stainless steel special-shaped part and a sintering method thereof, and belongs to the technical field of material processing.The sintering method comprises the following steps that a blank is placed in a sintering furnace, and a binder in the blank is removed through nitrogen gas flow introduced into the sintering furnace, so that the carbon content in the blank is smaller than or equal to 0.2%, and the oxygen content in the blank is smaller than or equal to 0.1%; argon is introduced when the degreased blank is in a sintering neck forming stage, a grain boundary growth stage and a pore spheroidizing stage, and stepped heating adjustment, heat preservation time adjustment and argon flow control are conducted on a sintering furnace according to different stages of the degreased blank in sequence, so that a primary sintered blank with the density larger than or equal to 7.5 g / cm < 3 > is obtained; and the sintering furnace is cooled, argon continues to be introduced into the sintering furnace, it is ensured that the internal phase body of the structure of the primary sintering blank is changed, and the sintering blank is obtained. By means of the method, the problems that in the prior art, a prepared F75 stainless steel special-shaped part is serious in deformation and unstable in size can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of material processing, and more specifically, to an F75 stainless steel special-shaped part and a sintering method thereof. Background Art

[0002] F75 alloy material has excellent corrosion resistance, high strength and high hardness, and is suitable for applications that withstand high loads and impacts. It can be used in high temperature and high pressure environments, and can withstand heavy static and dynamic loads. With the continuous upgrading of smart wearable devices, the requirements for materials are constantly increasing. F75 alloy material has great application potential. With the lightweight and miniaturization of smart devices, the production of thin F75 alloy parts with complex shapes has become a problem that needs to be solved.

[0003] The main problem currently faced in the production of F75 stainless steel special-shaped parts is that in the existing technology, the blank is placed in a sintering furnace, and the negative pressure degreasing time and temperature, vacuum sintering time and temperature, and partial pressure sintering time and temperature are set to perform a nitrogen sintering process. Since the entire process does not take into account the degree of degreasing and the changes in each stage of the blank during the sintering process, the obtained special-shaped structural parts have the problems of severe deformation and unstable size. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide an F75 stainless steel special-shaped part and a sintering method thereof, so as to solve the problem that in the prior art, by setting the negative pressure degreasing time and temperature, the vacuum sintering time and temperature, and the partial pressure sintering time and temperature, the nitrogen sintering process is carried out, and the obtained special-shaped structural parts have serious deformation and unstable size.

[0005] The present invention provides a method for sintering F75 stainless steel special-shaped parts, comprising the following steps:

[0006] Placing the blank in a sintering furnace, and removing the binder in the blank by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.2% and the oxygen content is ≤0.1%, thereby obtaining a defatted blank;

[0007] Argon is introduced into the degreased blank during the sintering neck formation stage, grain boundary growth stage and pore spheroidization stage, and the sintering furnace is adjusted in a stepwise manner according to the different stages of the degreased blank, the holding time is adjusted and the argon flow rate is controlled to obtain a density of ≥7.5g / cm 3 Primary sintering blank;

[0008] The sintering furnace is cooled down, and argon gas is continuously introduced into the sintering furnace to ensure the internal phase change of the primary sintered blank, thereby obtaining a sintered blank;

[0009] The temperature in the sintering furnace is cooled to room temperature, and the sintered blank in the sintering furnace is taken out to obtain a sintered product.

[0010] In addition, a preferred solution is that the step of placing the blank in a sintering furnace, removing the binder in the blank by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.2% and the oxygen content is ≤0.1%, and obtaining the defatted blank comprises:

[0011] Placing the blank in a sintering furnace, raising the temperature in the sintering furnace to 260-420° C., setting the holding time of the sintering furnace to 30-120 min, and removing the binder in the blank for the first time by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.4% and the oxygen content is ≤0.1%, thereby obtaining a first degreased blank;

[0012] The temperature in the sintering furnace is raised to 630-700° C., and the insulation time of the sintering furnace is set to 60-120 min. The binder in the first degreased blank is removed again by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the first degreased blank is ≤0.2% and the oxygen content is ≤0.1%, thereby obtaining a degreased blank.

[0013] In addition, a preferred solution is that, in the process of placing the blank in a sintering furnace, raising the temperature in the sintering furnace to 260-420° C., setting the holding time of the sintering furnace to 30-120 min, and removing the binder in the blank for the first time by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.4% and the oxygen content is ≤0.1%, and obtaining the first defatted blank,

[0014] The temperature in the sintering furnace is raised from room temperature to 260-420° C. over 60-90 minutes;

[0015] The temperature rise rate of the sintering furnace is 2-7°C / min;

[0016] The pressure of the nitrogen is 10-40 Pa, and the flow rate of the nitrogen is 15-45 L / min.

[0017] In addition, a preferred solution is that, in the process of raising the temperature in the sintering furnace to 630-700° C., setting the holding time of the sintering furnace to 60-120 min, and removing the binder in the first defatted blank again by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the first defatted blank is ≤0.2% and the oxygen content is ≤0.1%, and obtaining the defatted blank,

[0018] The temperature of the sintering furnace is raised to 630-700°C over 60-120 minutes;

[0019] The pressure of the nitrogen is 10-40 Pa, and the flow rate of the nitrogen is 15-45 L / min.

[0020] In addition, a preferred solution is that argon is introduced into the degreased blank during the sintering neck formation stage, the grain boundary growth stage and the pore spheroidization stage, and the sintering furnace is adjusted in a stepwise manner, the holding time is adjusted and the argon flow rate is controlled according to the different stages of the degreased blank, so as to obtain a density of ≥7.5g / cm 3 The primary sintering blanks include:

[0021] The temperature of the sintering furnace is raised to 900° C.-950° C., argon gas is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 30-60 minutes, so that the powder particles of the defatted blank are in contact with each other to form a combined sintering neck, thereby obtaining a first sintered blank;

[0022] The temperature of the sintering furnace is raised to 1000-1050° C., argon gas is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 30-60 min, so that a grain boundary grows at the powder contact point of the first sintered blank, thereby obtaining a second sintered blank;

[0023] The temperature of the sintering furnace is raised to 1200-1300°C, argon is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 200-500min, so that the pores of the second sintered blank are spheroidized to obtain a density of ≥7.5g / cm 3 Primary sintering blank.

[0024] In addition, a preferred solution is that, in the process of raising the temperature of the sintering furnace to 900-950° C., introducing argon into the sintering furnace, setting the holding time of the sintering furnace to 30-60 min, allowing the powder particles of the defatted blank to contact to form a combined sintering neck, and obtaining the first sintered blank,

[0025] After 80-120 minutes, the temperature of the sintering furnace is raised to 900° C.-950° C.;

[0026] The temperature rise rate of the sintering furnace is 1.5-2.6°C / min;

[0027] The pressure of the argon gas is 10-30 Pa, and the flow rate of the argon gas is 30-60 L / min.

[0028] In addition, a preferred solution is that, in the process of raising the temperature of the sintering furnace to 1000-1050° C., introducing argon into the sintering furnace, setting the holding time of the sintering furnace to 30-60 min, and growing grain boundaries at the powder contact points of the first sintered blank to obtain the second sintered blank,

[0029] Raising the temperature of the sintering furnace to 1000-1050° C. over 30-60 minutes;

[0030] The temperature rise rate of the sintering furnace is 1.5-3°C / min;

[0031] The pressure of the argon gas is 10-30 Pa, and the flow rate of the argon gas is 30-60 L / min.

[0032] In addition, a preferred solution is to raise the temperature of the sintering furnace to 1200-1300°C, introduce argon into the sintering furnace, set the holding time of the sintering furnace to 200-500min, spheroidize the pores of the second sintered blank, and obtain a density of ≥7.5g / cm 3 During the primary sintering of the blank,

[0033] Raising the temperature of the sintering furnace to 1200-1300° C. over 30-60 minutes;

[0034] The temperature rise rate of the sintering furnace is 1.5-3°C / min;

[0035] The pressure of the argon gas is 10-30 Pa, and the flow rate of the argon gas is 30-60 L / min.

[0036] In addition, a preferred solution is to cool the sintering furnace and continue to introduce argon into the sintering furnace to ensure that the internal phase of the primary sintered blank changes, and obtain the sintered blank comprising:

[0037] The temperature of the sintering furnace is lowered to 1100-800° C., argon gas is introduced into the sintering furnace, and the insulation time of the sintering furnace is set to 200-500 minutes to ensure the internal phase change of the structure of the primary sintered blank to obtain a sintered blank.

[0038] In addition, a preferred solution is that in the process of lowering the temperature of the sintering furnace to 1100-800°C, introducing argon into the sintering furnace, and setting the holding time of the sintering furnace to 200-500min, so as to ensure the internal phase change of the primary sintered blank, and obtaining the sintered blank,

[0039] The temperature of the sintering furnace is lowered to 1100-800° C. over 80-120 min;

[0040] The ramp rate of the sintering furnace is 3-5°C / min;

[0041] The pressure of the argon gas is 10-30 Pa, and the flow rate of the argon gas is 30-60 L / min.

[0042] The present invention provides an F75 stainless steel special-shaped part, which is manufactured by sintering a blank of the F75 stainless steel special-shaped part by adopting the above-mentioned F75 stainless steel special-shaped part sintering method.

[0043] It can be seen from the above technical scheme that the F75 stainless steel special-shaped parts and the sintering method thereof provided by the present invention first perform negative pressure degreasing to remove the binder in the blank from the product, and control the carbon content in the blank to ≤0.2%, thereby combining the subsequent degreasing blank in the sintering neck formation stage, grain boundary growth stage, and connected pore spheroidization stage to control the temperature, holding time, furnace pressure, and argon flow rate in the furnace to ensure that the density of the blank is ≥7.5g / cm 3 , so as to reduce the sintering deformation of the product; by controlling the oxygen content ≤0.1%, the compound impurities formed by the combination of elements and oxygen in the blank can be reduced during the subsequent partial pressure sintering process, thereby reducing the influence of the compound impurities on the quality of the sintered product; by adopting the temperature reduction partial pressure sintering method for the blank, the internal phase change of the blank organization is ensured, and finally the temperature is reduced to room temperature to obtain the sintered product, so that the shape of the sintered product is more stable; thus, the present invention can prepare a special-shaped structure with more stable size, so as to solve the sintering deformation problem of special-shaped structural parts in the current prior art, and effectively control the dimensional stability and deformation of the parts after sintering.

[0044] In order to achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings describe some exemplary aspects of the present invention in detail. However, these aspects indicate only some of the various ways in which the principles of the present invention can be used. In addition, the present invention is intended to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] By referring to the following description in conjunction with the accompanying drawings, and with a more complete understanding of the present invention, other objects and results of the present invention will become more apparent and easily understood.

[0046] Figure 1 This is a flow chart of a method for sintering F75 stainless steel special-shaped parts according to an embodiment of the present invention;

[0047] Figure 2 4 is a sintering curve diagram of F75 stainless steel special-shaped parts according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In the following description, for the purpose of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. However, it is apparent that these embodiments may also be implemented without these specific details.

[0049] In view of the above-mentioned prior art, in which a nitrogen sintering process is performed by setting the negative pressure degreasing time and temperature, the vacuum sintering time and temperature, and the partial pressure sintering time and temperature, the obtained special-shaped structural parts have the problems of severe deformation and unstable size. An F75 stainless steel special-shaped part and a sintering method thereof are proposed.

[0050] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] In order to illustrate the F75 stainless steel special-shaped parts and the sintering method thereof provided by the present invention, Figure 1 The process of the sintering method of F75 stainless steel special-shaped parts according to an embodiment of the present invention is shown; Figure 2 The sintering curve of F75 stainless steel special-shaped parts according to an embodiment of the present invention is shown.

[0052] like Figure 1 As shown, the F75 stainless steel special-shaped part sintering method provided by the present invention comprises the following steps:

[0053] Step S1, placing the blank in a sintering furnace, and removing the binder in the blank by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.2%, and the oxygen content is ≤0.1%, thereby obtaining a defatted blank.

[0054] Specifically, the F75 stainless steel special-shaped blank to be sintered is placed in a sintering furnace, and the binder in the blank is removed by introducing a nitrogen gas flow into the sintering furnace until the carbon content in the blank is ≤0.2% and the oxygen content is ≤0.1%, so as to obtain a degreased blank. During the negative pressure degreasing process, the carbon content in the blank is ≤0.2%, which ensures that the density of the blank is ≥7.5g / cm in the subsequent partial pressure sintering process. 3 A factor of the blank density ≥7.5g / cm 3 , the internal voids are small, which is one of the factors that reduce the sintering deformation of the product. Controlling the oxygen content ≤0.1% can reduce the combination of elements and oxygen in the blank during the subsequent partial pressure sintering process, thereby reducing the generated compound impurities. Compound impurities during the sintering process are also one of the factors affecting product deformation. As a preferred embodiment of the present invention, the blank is placed in a sintering furnace, and the binder in the blank is removed by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.2% and the oxygen content is ≤0.1%. Obtaining a defatted blank includes:

[0055] Placing the blank in a sintering furnace, raising the temperature in the sintering furnace to 260-420° C., setting the holding time of the sintering furnace to 30-120 min, and removing the binder in the blank for the first time by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.4% and the oxygen content is ≤0.1%, thereby obtaining a first degreased blank;

[0056] The temperature in the sintering furnace is raised to 630-700°C, and the insulation time of the sintering furnace is set to 60-120min. The binder in the first degreased blank is removed again by introducing a nitrogen flow into the sintering furnace, so that the carbon content in the first degreased blank is ≤0.2% and the oxygen content is ≤0.1%, thereby obtaining a degreased blank.

[0057] Specifically, the sintering furnace is heated twice to ensure that the carbon content in the blank is ≤0.2% and the oxygen content is ≤0.1%, so as to reduce the influence of impurity elements such as various compounds during the sintering process of the blank.

[0058] As a preferred embodiment of the present invention, the blank is placed in a sintering furnace, the temperature in the sintering furnace is raised to 260-420°C, the holding time of the sintering furnace is set to 30-120min, and the binder in the blank is first removed by a nitrogen gas flow introduced into the sintering furnace, so that the carbon content in the blank is ≤0.4% and the oxygen content is ≤0.1%, and in the process of obtaining the first defatted blank,

[0059] The temperature in the sintering furnace is raised from room temperature to 260-420°C over 60-90 minutes;

[0060] The temperature rise rate of the sintering furnace is 2-7℃ / min;

[0061] The pressure of nitrogen is 10-40Pa, and the flow rate of nitrogen is 15-45L / min.

[0062] Specifically, the above method can ensure that after the blank is subjected to the first negative pressure degreasing, the carbon content in the blank is ≤0.4% and the oxygen content is ≤0.1%.

[0063] As a preferred embodiment of the present invention, the temperature in the sintering furnace is raised to 630-700° C., the holding time of the sintering furnace is set to 60-120 min, and the binder in the first degreased blank is removed again by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the first degreased blank is ≤0.2% and the oxygen content is ≤0.1%. In the process of obtaining the degreased blank,

[0064] The temperature of the sintering furnace is raised to 630-700°C over 60-120 minutes;

[0065] The pressure of nitrogen is 10-40Pa, and the flow rate of nitrogen is 15-45L / min.

[0066] Specifically, the above method can ensure that after the second negative pressure degreasing of the blank, the carbon content in the blank is ≤0.2% and the oxygen content is ≤0.1%.

[0067] Step S2: Argon is introduced into the degreased blank during the sintering neck formation stage, grain boundary growth stage, and pore spheroidization stage, and the sintering furnace is adjusted in a stepwise manner according to the different stages of the degreased blank, the holding time is adjusted, and the argon flow rate is controlled to obtain a density of ≥7.5g / cm 3 Primary sintering blank.

[0068] Specifically, the degreased blank generally needs to go through the neck formation stage, grain boundary growth stage and pore spheroidization stage during the partial pressure sintering process. By adjusting the sintering furnace temperature, holding time and argon flow rate in each of the above stages in turn, the factors that lead to product defects in each stage can be eliminated, and the density of the blank can be controlled to be ≥7.5g / cm 3 .

[0069] As a preferred embodiment of the present invention, argon is introduced into the degreased blank during the sintering neck formation stage, grain boundary growth stage and pore spheroidization stage, and the sintering furnace is adjusted in a stepwise manner according to the different stages of the degreased blank, the holding time is adjusted and the argon flow rate is controlled to obtain a density of ≥7.5g / cm 3 The primary sintering blanks include:

[0070] The temperature of the sintering furnace is raised to 900° C.-950° C., argon gas is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 30-60 minutes, so that the powder particles of the degreased blank are in contact to form a combined sintering neck, thereby obtaining a first sintered blank;

[0071] The temperature of the sintering furnace is raised to 1000-1050° C., argon gas is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 30-60 minutes, so that the grain boundary grows at the powder contact point of the first sintered blank, thereby obtaining a second sintered blank;

[0072] The temperature of the sintering furnace is raised to 1200-1300℃, argon is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 200-500min to spheroidize the pores of the second sintered blank to obtain a density of ≥7.5g / cm 3 Primary sintering blank.

[0073] Specifically, the degreased blank enters the sintering neck formation stage during the partial pressure sintering process. In this stage, the blank powder particles are contacted to form a combined sintering neck by controlling the furnace temperature, holding time, and argon flow rate. After a period of heat preservation, the sintering furnace is heated up again. At this time, the blank enters the grain boundary growth stage. By controlling the furnace temperature, holding time, and argon flow rate, the sintering neck grows, the combination between the powders continues to expand and merge, and a grain boundary grows at the contact point to replace the solid-gas interface. The pores between the powders begin to become smooth and interconnected. After a period of heat preservation, the sintering furnace is heated up again. At this time, the blank enters the pore spheroidization stage. The furnace temperature, holding time, and argon flow rate are controlled to make the powder shrink violently and eliminate a large number of connected pores at the same time, and the pores are spheroidized. By controlling the temperature, holding time, and argon flow rate at different sintering stages, the density of the blank can be controlled, and defects such as cracks can be eliminated in time, so that the prepared product has dimensional stability and small deformation.

[0074] As a preferred embodiment of the present invention, in the process of raising the temperature of the sintering furnace to 900-950°C, introducing argon into the sintering furnace, setting the holding time of the sintering furnace to 30-60 minutes, making the powder particles of the defatted blank contact to form a combined sintering neck, and obtaining the first sintered blank,

[0075] After 80-120 minutes, the temperature of the sintering furnace is raised to 900°C-950°C;

[0076] The temperature rise rate of the sintering furnace is 1.5-2.6℃ / min;

[0077] The pressure of argon gas is 10-30 Pa, and the flow rate of argon gas is 30-60 L / min.

[0078] Specifically, by setting the above parameters, the sintering neck of the blank can be formed smoothly.

[0079] As a preferred embodiment of the present invention, the temperature of the sintering furnace is raised to 1000-1050° C., argon gas is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 30-60 minutes, so that the grain boundary grows at the powder contact point of the first sintered blank to obtain the second sintered blank.

[0080] Raise the temperature of the sintering furnace to 1000-1050°C over 30-60 minutes;

[0081] The temperature rise rate of the sintering furnace is 1.5-3℃ / min;

[0082] The pressure of argon gas is 10-30 Pa, and the flow rate of argon gas is 30-60 L / min.

[0083] Specifically, by setting the above parameters, the pores between powders can be smoothed during the grain boundary growth process of the blank, and the smooth progress of this stage can be ensured.

[0084] As a preferred embodiment of the present invention, the temperature of the sintering furnace is raised to 1200-1300°C, argon is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 200-500min, so that the pores of the second sintered blank are spheroidized to obtain a density of ≥7.5g / cm 3 During the primary sintering of the blank,

[0085] Raise the temperature of the sintering furnace to 1200-1300°C over 30-60 minutes;

[0086] The temperature rise rate of the sintering furnace is 1.5-3℃ / min;

[0087] The pressure of argon gas is 10-30 Pa, and the flow rate of argon gas is 30-60 L / min.

[0088] Specifically, during the pore spheroidization stage, defects such as holes and cracks in the product can be eliminated.

[0089] Step S3, cooling the sintering furnace and continuing to introduce argon into the sintering furnace to ensure the internal phase changes of the primary sintered blank to obtain a sintered blank.

[0090] Specifically, by cooling the sintering furnace and continuing to introduce argon gas, the internal phase changes of the product structure can be ensured, and the low dew point characteristic of argon gas can be used to ensure the surface gloss of the product.

[0091] As a preferred embodiment of the present invention, the sintering furnace is cooled down, and argon gas is continuously introduced into the sintering furnace to ensure the internal phase change of the primary sintered blank. The sintered blank comprises:

[0092] The temperature of the sintering furnace is lowered to 1100-800°C, argon gas is introduced into the sintering furnace, and the insulation time of the sintering furnace is set to 200-500 minutes to ensure the internal phase change of the primary sintered blank to obtain the sintered blank.

[0093] As a preferred embodiment of the present invention, when the temperature of the sintering furnace is lowered to 1100-800°C, argon is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 200-500min to ensure the internal phase change of the primary sintered blank, in the process of obtaining the sintered blank,

[0094] The temperature of the sintering furnace is lowered to 1100-800°C over 80-120 minutes;

[0095] The temperature rise and fall rate of the sintering furnace is 3-5℃ / min;

[0096] The pressure of argon gas is 10-30 Pa, and the flow rate of argon gas is 30-60 L / min.

[0097] Through the above-mentioned specific parameter settings, the phase changes within the organization can be effectively guaranteed and the dimensional stability of the product can be increased.

[0098] Step S4, cooling the temperature in the sintering furnace to room temperature, taking out the sintered blank in the sintering furnace, and obtaining a sintered product.

[0099] The F75 stainless steel special-shaped part provided by the present invention is obtained by sintering the F75 stainless steel special-shaped part blank by adopting the F75 stainless steel special-shaped part sintering method described above by the present invention.

[0100] In order to better explain in detail the F75 stainless steel special-shaped parts and the sintering method thereof provided by the present invention and the technical effects achieved by the same, the following examples are given:

[0101] The F75 stainless steel special-shaped parts to be sintered are placed in the sintering furnace, and then the sintering process is carried out in the following steps:

[0102] Example 1

[0103] Negative pressure degreasing: raise the temperature in the sintering furnace from room temperature to 260°C within 60-90 minutes, keep it warm for 30 minutes, and introduce nitrogen (N2), wherein the pressure of nitrogen is 10Pa and the flow rate is 15L / min; raise the temperature in the sintering furnace at a heating rate of 2-7°C / min, and use the nitrogen gas flow to remove the binder in the blank from the product during the heating process. The carbon content of the blank obtained is 0.3%, and the oxygen content is 0.08%.

[0104] Negative pressure degreasing: the temperature in the sintering furnace is raised to 630°C within 60-120 minutes, kept warm for 60 minutes, and nitrogen is introduced, wherein the pressure of the nitrogen is 10Pa and the flow rate is 15L / min; during the heating and keeping warm process, the binder in the blank is removed from the product by the nitrogen flow, and the obtained blank has a carbon content of 0.18% and an oxygen content of 0.07%.

[0105] Partial pressure sintering: raise the temperature in the sintering furnace to 900°C within 80-120 minutes, keep it warm for 30 minutes, and introduce argon (AR), wherein the pressure of argon is 10Pa and the flow rate is 30L / min; the temperature in the sintering furnace is raised at a heating rate of 1.5-2.6°C / min, at which time, the powder particles of the blank are in contact to form a combined sintering neck.

[0106] Partial pressure sintering: raise the temperature in the sintering furnace to 1000°C within 30-60 minutes, keep it warm for 30 minutes, and introduce argon gas with a pressure of 10Pa and a flow rate of 30L / min. The temperature rise rate in the sintering furnace is 1.5-3°C / min. At this time, as the sintering neck of the blank grows, the bonding between the powders continues to expand and merge, and grain boundaries grow at the contact points to replace the solid-gas interface. The pores between the powders begin to become smooth and interconnected.

[0107] Partial pressure sintering: The temperature in the sintering furnace is raised to 1200℃ for 80-120min and kept at this temperature for 200min. Argon gas is introduced with a pressure of 10Pa and a flow rate of 30L / min. The temperature in the sintering furnace is raised at a heating rate of 1-3℃ / min. At this time, the powder shrinks violently and eliminates a large number of interconnected pores, and the pores are spheroidized. At this time, the density of the blank obtained is 7.52g / cm 3 .

[0108] Partial pressure sintering: cool the temperature in the sintering furnace to 1100℃ within 80-120min, keep it warm for 200min, and introduce argon gas with a pressure of 10Pa and a flow rate of 30L / min. The cooling rate in the sintering furnace is 3-5℃ / min to ensure the phase change inside the organization and use the low dew point characteristics of argon gas to ensure the surface gloss of the product.

[0109] The temperature of the sintering furnace is cooled to room temperature, and the sintered blank is taken out to obtain a sintered product.

[0110] Among them, the contour of the sintered product is stable within 0.07.

[0111] Example 2

[0112] Negative pressure degreasing: raise the temperature in the sintering furnace from room temperature to 350°C within 60-90 minutes, keep the temperature for 80 minutes, and introduce nitrogen (N2), wherein the pressure of nitrogen is 20Pa and the flow rate is 30L / min; raise the temperature in the sintering furnace at a heating rate of 2-7°C / min, and use the nitrogen gas flow to remove the binder in the blank from the product during the heating process, and the carbon content of the blank obtained is 0.28%, and the oxygen content is 0.08%.

[0113] Negative pressure degreasing: the temperature in the sintering furnace is raised to 650°C within 60-120 minutes, kept warm for 80 minutes, and nitrogen is introduced, wherein the pressure of the nitrogen is 20Pa and the flow rate is 30L / min; during the heating and heat preservation process, the binder in the blank is removed from the product by the nitrogen flow, and the carbon content of the blank obtained is 0.12%, and the oxygen content is 0.07%.

[0114] Partial pressure sintering: raise the temperature in the sintering furnace to 920°C within 80-120 minutes, keep it warm for 40 minutes, and introduce argon (AR), wherein the pressure of argon is 15Pa and the flow rate is 50L / min; the temperature in the sintering furnace is raised at a heating rate of 1.5-2.6°C / min, at which time, the powder particles of the blank are in contact to form a combined sintering neck.

[0115] Partial pressure sintering: raise the temperature in the sintering furnace to 1020°C within 30-60 minutes, keep warm for 50 minutes, and introduce argon gas with a pressure of 15Pa and a flow rate of 50L / min. The temperature rise rate in the sintering furnace is 1.5-3°C / min. At this time, as the sintering neck of the blank grows, the bonding between the powders continues to expand and merge, and grain boundaries grow at the contact points to replace the solid-gas interface. The pores between the powders begin to become smooth and interconnected.

[0116] Partial pressure sintering: Raise the temperature in the sintering furnace to 1250℃ for 80-120min and keep it for 300min. Then introduce argon gas with a pressure of 15Pa and a flow rate of 50L / min. Raise the temperature in the sintering furnace at a rate of 1-3℃ / min. At this time, the powder shrinks violently and eliminates a large number of interconnected pores, and the pores are spheroidized. At this time, the density of the blank is 7.55g / cm 3 .

[0117] Partial pressure sintering: cool the temperature in the sintering furnace to 1000℃ within 80-120min, keep it warm for 300min, and introduce argon gas with a pressure of 15Pa and a flow rate of 50L / min. The cooling rate in the sintering furnace is 3-5℃ / min to ensure the internal phase changes of the organization and to ensure the surface gloss of the product by using the low dew point characteristics of argon gas.

[0118] The temperature of the sintering furnace is cooled to room temperature, and the sintered blank is taken out to obtain a sintered product.

[0119] Among them, the contour of the sintered product is stable within 0.07.

[0120] Example 3

[0121] Negative pressure degreasing: raise the temperature in the sintering furnace from room temperature to 420°C within 60-90 minutes, keep it warm for 120 minutes, and introduce nitrogen (N2), wherein the pressure of nitrogen is 40Pa and the flow rate is 45L / min; raise the temperature in the sintering furnace at a heating rate of 2-7°C / min, and use the nitrogen gas flow to remove the binder in the blank from the product during the heating process. The carbon content of the blank obtained is 0.22%, and the oxygen content is 0.07%.

[0122] Negative pressure degreasing: the temperature in the sintering furnace is raised to 700°C within 60-120 minutes, kept warm for 120 minutes, and nitrogen is introduced, wherein the pressure of the nitrogen is 40Pa and the flow rate is 45L / min; during the heating and keeping warm process, the binder in the blank is removed from the product by the nitrogen flow, and the carbon content of the blank obtained is 0.1%, and the oxygen content is 0.068%.

[0123] Partial pressure sintering: raise the temperature in the sintering furnace to 950°C within 80-120 minutes, keep it warm for 60 minutes, and introduce argon (AR), wherein the pressure of argon is 30Pa and the flow rate is 60L / min; the temperature in the sintering furnace is raised at a heating rate of 1.5-2.6°C / min, at which time, the powder particles of the blank are in contact to form a combined sintering neck.

[0124] Partial pressure sintering: raise the temperature in the sintering furnace to 1050°C within 30-60 minutes, keep it warm for 60 minutes, and introduce argon gas with a pressure of 30Pa and a flow rate of 60L / min. The temperature rise rate in the sintering furnace is 1.5-3°C / min. At this time, as the sintering neck of the blank grows, the bonding between the powders continues to expand and merge, and grain boundaries grow at the contact points to replace the solid-gas interface. The pores between the powders begin to become smooth and interconnected.

[0125] Partial pressure sintering: The temperature in the sintering furnace is raised to 1300℃ for 80-120min and kept at this temperature for 500min. Argon gas is introduced with a pressure of 30Pa and a flow rate of 60L / min. The temperature in the sintering furnace is raised at a heating rate of 1-3℃ / min. At this time, the powder shrinks violently and eliminates a large number of interconnected pores, and the pores are spheroidized. At this time, the density of the blank is 7.6g / cm 3 .

[0126] Partial pressure sintering: cool the temperature in the sintering furnace to 800℃ within 80-120min, keep it warm for 500min, and introduce argon gas with a pressure of 30Pa and a flow rate of 60L / min. The cooling rate in the sintering furnace is 3-5℃ / min to ensure the internal phase changes of the organization and to ensure the surface gloss of the product by using the low dew point characteristics of argon gas.

[0127] The temperature of the sintering furnace is cooled to room temperature, and the sintered blank is taken out to obtain a sintered product.

[0128] Among them, the contour of the sintered product is stable within 0.07.

[0129] Comparative Example 1

[0130] Negative pressure degreasing: the temperature is 650℃, the time is 360min, the carbon content in the blank is detected to be about 0.35%, and the oxygen content is 0.18%.

[0131] The process of partial pressure sintering is the same as that in Example 1. The density of the blank after partial pressure sintering is 7.3 g / cm 3 .

[0132] The contour of the obtained product is stable at 0.1-0.3.

[0133] Comparative Example 2

[0134] Negative pressure degreasing: the temperature is 650℃, the time is 360min, the carbon content in the blank is detected to be about 0.35%, and the oxygen content is about 0.18%.

[0135] The partial pressure sintering process is the same as that in Example 2. The density of the blank after partial pressure sintering is 7.35 g / cm 3 .

[0136] The contour of the obtained product is stable at 0.1-0.3.

[0137] Comparative Example 3

[0138] Negative pressure degreasing: the temperature is 650℃, the time is 360min, the carbon content in the blank is detected to be about 0.35%, and the oxygen content is about 0.18%.

[0139] The partial pressure sintering process is the same as that in Example 3. The density of the blank after partial pressure sintering is 7.4 g / cm 3 .

[0140] The contour of the obtained product is stable at 0.1-0.3.

[0141] Comparative Example 4

[0142] The negative pressure degreasing process is the same as that in Example 1. After the negative pressure degreasing, the carbon content of the blank is 0.18%, and the oxygen content is 0.07%.

[0143] Vacuum sintering: temperature is 1100℃, time is 180min.

[0144] The partial pressure sintering temperature is 1400℃ and the time is 360min. The density of the blank after partial pressure sintering is 7.38g / cm 3 .

[0145] The contour of the obtained product is stable at about 0.3.

[0146] Comparative Example 5

[0147] Negative pressure degreasing: temperature is 650℃, time is 360min, the carbon content in the blank is detected to be 0.35%, and the oxygen content is 0.18%.

[0148] Vacuum sintering: temperature is 1100℃, time is 180min.

[0149] Partial pressure sintering: temperature is 1400℃, time is 360min, after testing, the density of the blank after partial pressure sintering is 7.2g / cm 3 .

[0150] The contour of the obtained product is stable at about 0.3.

[0151] It should be noted that the results obtained in the above-mentioned Examples 1-3 and Comparative Examples 1-5 are all the results of multiple tests, and therefore the obtained contours are generalized values ​​based on multiple tests.

[0152] It can be seen from the above specific embodiments that the F75 stainless steel special-shaped parts and the sintering method thereof provided by the present invention, the F75 stainless steel special-shaped parts and the sintering method thereof provided by the present invention, by first performing negative pressure degreasing, the binder in the blank is removed from the product, and the carbon content in the blank is controlled to be ≤0.2%, thereby combining the subsequent degreased blank in the sintering neck formation stage, the grain boundary growth stage, and the connected pore spheroidization stage to control the temperature in the furnace, the holding time, the furnace pressure, and the argon flow rate to ensure that the density of the blank is ≥7.5g / cm 3 , so as to reduce the sintering deformation of the product; by controlling the oxygen content ≤0.1%, the compound impurities formed by the combination of elements and oxygen in the blank can be reduced during the subsequent partial pressure sintering process, thereby reducing the influence of the compound impurities on the quality of the sintered product; by adopting the temperature reduction partial pressure sintering method for the blank, the internal phase change of the blank organization is ensured, and finally the temperature is reduced to room temperature to obtain the sintered product, so that the shape of the sintered product is more stable; thus, the present invention can prepare a special-shaped structure with more stable size, so as to solve the sintering deformation problem of special-shaped structural parts in the current prior art, and effectively control the dimensional stability and deformation of the parts after sintering.

[0153] As described above, the F75 stainless steel special-shaped parts and the sintering method thereof proposed in the present invention are described by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various improvements can be made to the F75 stainless steel special-shaped parts and the sintering method thereof proposed in the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the attached claims.

Claims

1. A method for sintering F75 stainless steel special-shaped parts, characterized in that: The steps include: Placing the blank in a sintering furnace, and removing the binder in the blank by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.2% and the oxygen content is ≤0.1%, thereby obtaining a defatted blank; Argon is introduced into the degreased blank during the sintering neck formation stage, grain boundary growth stage and pore spheroidization stage, and the sintering furnace is adjusted in a stepwise manner according to the different stages of the degreased blank, the holding time is adjusted and the argon flow rate is controlled to obtain a density of ≥7.5g / cm 3 Primary sintering blank; The sintering furnace is cooled down, and argon gas is continuously introduced into the sintering furnace to ensure the internal phase change of the primary sintered blank, thereby obtaining a sintered blank; The temperature in the sintering furnace is cooled to room temperature, and the sintered blank in the sintering furnace is taken out to obtain a sintered product.

2. The method for sintering F75 stainless steel special-shaped parts according to claim 1, characterized in that: Placing the blank in a sintering furnace, removing the binder in the blank by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.2% and the oxygen content is ≤0.1%, and obtaining the defatted blank comprises: Placing the blank in a sintering furnace, raising the temperature in the sintering furnace to 260-420° C., setting the holding time of the sintering furnace to 30-120 min, and removing the binder in the blank for the first time by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.4% and the oxygen content is ≤0.1%, thereby obtaining a first degreased blank; The temperature in the sintering furnace is raised to 630-700° C., and the insulation time of the sintering furnace is set to 60-120 min. The binder in the first degreased blank is removed again by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the first degreased blank is ≤0.2% and the oxygen content is ≤0.1%, thereby obtaining a degreased blank.

3. The sintering method of F75 stainless steel special-shaped parts according to claim 2, characterized in that: In the process of placing the blank in a sintering furnace, raising the temperature in the sintering furnace to 260-420° C., setting the holding time of the sintering furnace to 30-120 min, and removing the binder in the blank for the first time by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the blank is ≤0.4% and the oxygen content is ≤0.1%, and obtaining the first defatted blank, The temperature in the sintering furnace is raised from room temperature to 260-420° C. over 60-90 minutes; The temperature rise rate of the sintering furnace is 2-7°C / min; The pressure of the nitrogen is 10-40 Pa, and the flow rate of the nitrogen is 15-45 L / min.

4. The method for sintering F75 stainless steel special-shaped parts according to claim 2, characterized in that: In the process of raising the temperature in the sintering furnace to 630-700° C., setting the holding time of the sintering furnace to 60-120 min, and removing the binder in the first defatted blank again by introducing a nitrogen gas flow into the sintering furnace, so that the carbon content in the first defatted blank is ≤0.2% and the oxygen content is ≤0.1%, and obtaining the defatted blank, The temperature of the sintering furnace is raised to 630-700°C over 60-120 minutes; The pressure of the nitrogen is 10-40 Pa, and the flow rate of the nitrogen is 15-45 L / min.

5. The method for sintering F75 stainless steel special-shaped parts according to claim 1, characterized in that: Argon is introduced into the degreased blank during the sintering neck formation stage, grain boundary growth stage and pore spheroidization stage, and the sintering furnace is adjusted in a stepwise manner, the holding time is adjusted and the argon flow rate is controlled according to the different stages of the degreased blank to obtain a density of ≥7.5g / cm 3 The primary sintering blanks include: The temperature of the sintering furnace is raised to 900° C.-950° C., argon gas is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 30-60 minutes, so that the powder particles of the defatted blank are in contact with each other to form a combined sintering neck, thereby obtaining a first sintered blank; The temperature of the sintering furnace is raised to 1000-1050° C., argon gas is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 30-60 min, so that a grain boundary grows at the powder contact point of the first sintered blank, thereby obtaining a second sintered blank; The temperature of the sintering furnace is raised to 1200-1300°C, argon is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 200-500min, so that the pores of the second sintered blank are spheroidized to obtain a density of ≥7.5g / cm 3 Primary sintering blank.

6. The method for sintering F75 stainless steel special-shaped parts according to claim 5, characterized in that: In the process of raising the temperature of the sintering furnace to 900-950° C., introducing argon into the sintering furnace, setting the holding time of the sintering furnace to 30-60 min, making the powder particles of the degreased blank contact to form a combined sintering neck, and obtaining the first sintered blank, After 80-120 minutes, the temperature of the sintering furnace is raised to 900° C.-950° C.; The temperature rise rate of the sintering furnace is 1.5-2.6°C / min; The pressure of the argon gas is 10-30 Pa, and the flow rate of the argon gas is 30-60 L / min.

7. The method for sintering F75 stainless steel special-shaped parts according to claim 5, characterized in that: In the process of raising the temperature of the sintering furnace to 1000-1050° C., introducing argon into the sintering furnace, setting the holding time of the sintering furnace to 30-60 min, and growing grain boundaries at the powder contact points of the first sintered blank to obtain the second sintered blank, Raising the temperature of the sintering furnace to 1000-1050° C. over 30-60 minutes; The temperature rise rate of the sintering furnace is 1.5-3°C / min; The pressure of the argon gas is 10-30 Pa, and the flow rate of the argon gas is 30-60 L / min.

8. The method for sintering F75 stainless steel special-shaped parts according to claim 5, characterized in that: The temperature of the sintering furnace is raised to 1200-1300° C., argon is introduced into the sintering furnace, and the holding time of the sintering furnace is set to 200-500 min, so that the pores of the second sintered blank are spheroidized to obtain a density of ≥7.5 g / cm 3 During the primary sintering of the blank, Raising the temperature of the sintering furnace to 1200-1300° C. over 30-60 minutes; The temperature rise rate of the sintering furnace is 1.5-3°C / min; The pressure of the argon gas is 10-30 Pa, and the flow rate of the argon gas is 30-60 L / min.

9. The method for sintering F75 stainless steel special-shaped parts according to claim 5, characterized in that: The sintering furnace is cooled down, and argon gas is continuously introduced into the sintering furnace to ensure the internal phase change of the primary sintered blank. The sintered blank comprises: The temperature of the sintering furnace is lowered to 1100-800° C., argon gas is introduced into the sintering furnace, and the insulation time of the sintering furnace is set to 200-500 minutes to ensure the internal phase change of the structure of the primary sintered blank to obtain a sintered blank.

10. The method for sintering F75 stainless steel special-shaped parts according to claim 9, characterized in that: In the process of lowering the temperature of the sintering furnace to 1100-800° C., introducing argon into the sintering furnace, and setting the holding time of the sintering furnace to 200-500 min to ensure the internal phase change of the primary sintered blank, The temperature of the sintering furnace is lowered to 1100-800° C. over 80-120 min; The ramp rate of the sintering furnace is 3-5°C / min; The pressure of the argon gas is 10-30 Pa, and the flow rate of the argon gas is 30-60 L / min.

11. An F75 stainless steel special-shaped part, characterized in that: The special-shaped F75 stainless steel part is prepared by sintering the blank of the special-shaped F75 stainless steel part using the special-shaped F75 stainless steel part sintering method as described in any one of claims 1 to 10.

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