Martensitic stainless steel cutter heat treatment method

Abstract

The invention relates to a martensitic stainless steel cutter heat treatment method. The method comprises the following steps that (1) the martensitic stainless steel cutter is fed into a heating furnace to be heated; and (2) the cutter heated in the step (1) is fed into a cooling box body. Wherein in the step 2), sealing doors are arranged at the two ends of the cooling box body to isolate air, protective gas is fed into one end of the cooling box body, the protective gas is discharged from the other end of the cooling box body, and the cooling speed of the cutter can be increased and the surface of the cutter can be prevented from being oxidized by feeding the protective gas. The cooling box body is provided with the sealing door used for isolating air from the to-be-cooled tool and continuously introducing the protective gas, so that the tool can be prevented from being oxidized, the cooling speed of the tool can be increased, carbide is prevented from being gathered on an original austenite grain boundary, the corrosion resistance is improved, and the pitting phenomenon is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment of cutting tools, and in particular to a heat treatment method of a martensitic stainless steel cutting tool. Background Art

[0002] The heat treatment process of martensitic stainless steel knives is usually carried out in a conveyor-type heat treatment furnace. Specifically, the blanks are evenly placed on the conveyor belt after unloading, and are transported by the conveyor belt through the heating furnace, cooling furnace and flattening device in turn. The cooling furnace generally uses a cooling furnace with openings at both ends for air cooling. By adjusting the running speed of the conveyor belt, the time of the heating and cooling process of the blanks is controlled. In actual production, it was found that the microstructure of some knives showed serious abnormalities, and the distribution of carbides was highly concentrated on the original austenite grain boundaries, resulting in worse corrosion resistance of the already fragile original austenite grain boundaries. In the subsequent salt water erosion test, the performance was unqualified, and a large number of pitting corrosion phenomena occurred, which seriously affected the quality and pass rate of the product. In addition, the surface of the blade is composed of a thick oxide layer, which is difficult to remove in the subsequent production process. Summary of the invention

[0003] The purpose of the present invention is to provide a heat treatment method for martensitic stainless steel cutting tools to solve the above technical problems existing in the prior art.

[0004] To achieve the above-mentioned purpose, a heat treatment method for a martensitic stainless steel tool of the present invention adopts the following technical scheme: A heat treatment method for a martensitic stainless steel tool comprises the following steps:

[0005] 1) The martensitic stainless steel tool is sent into a heating furnace for heating treatment;

[0006] 2) the tool after the heating treatment in step 1) is sent into a cooling box;

[0007] In step 2), sealed doors are provided at both ends of the cooling box to isolate the air, and protective gas is introduced into one end of the cooling box and discharged from the other end of the cooling box. The introduction of protective gas can increase the cooling speed of the tool and prevent oxidation of the tool surface.

[0008] In step 2), a first cooling fan is provided on the inner top plate at one end of the cooling box body close to the heating furnace, and a second cooling fan is provided on the inner top plate at the other end of the cooling box body to accelerate the flow rate of the protective gas to increase the cooling speed of the tool.

[0009] In step 2), a flow guide device is provided in the cooling box to guide the flow of the protective gas.

[0010] The guide device includes an arc-shaped air supply plate arranged at one end of the cooling box, which is used to introduce the above-mentioned protective gas into the interior of the cooling box, and the lower end of the arc-shaped air supply plate blows air obliquely downward along the transmission direction of the tool; the guide device also includes an arc-shaped exhaust plate arranged at the other end of the cooling box, and the lower end of the arc-shaped exhaust plate draws air obliquely upward along the transmission direction of the tool to extract the protective gas in the cooling box.

[0011] In step 2), the protective gas is selected from nitrogen gas, ethanol gas or a mixture of the two.

[0012] The tool after cooling treatment in step 2) is then tempered.

[0013] The tempering temperature is 150-180℃.

[0014] The heat treatment method for martensitic stainless steel cutting tools according to claim 1 is characterized in that a protective gas is passed through the heating furnace to prevent oxidation of the cutting tools.

[0015] The beneficial effects of the present invention are as follows: the cooling box has a sealed door for isolating the tool to be cooled from the air and continuously introducing protective gas, which can not only prevent the tool from being oxidized, but also reduce the cooling speed of the tool and prevent carbides from accumulating on the original austenite grain boundaries, thereby increasing corrosion resistance and reducing the occurrence of pitting corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of a heat treatment device used in an embodiment of a heat treatment method for a martensitic stainless steel tool of the present invention;

[0017] Figure 2 This is the tool sample obtained after heat treatment in the comparative example;

[0018] Figure 3 yes Figure 2 Microstructure diagram of the cutting tool sample;

[0019] Figure 4 3 is the microstructure diagram of the tool sample obtained in Example 1. DETAILED DESCRIPTION

[0020] Embodiment 1

[0021] A heat treatment method for a martensitic stainless steel tool comprises the following steps:

[0022] 1) The martensitic stainless steel tool is sent into a heating furnace for heating treatment.

[0023] In step 1), the temperature and time of the heating treatment can be selected according to the material and the different performance requirements of the enterprise. This embodiment will not be described in detail. The existing heating treatment temperature and time and adjustment can be referred to. A protective gas is introduced into the heating furnace to prevent oxidation of the tool. The heating furnace adopts the existing conveyor belt heating furnace. The protective gas adopts nitrogen.

[0024] 2) The tool after the heating treatment in step 1) is sent to a cooling box.

[0025] In step 2), sealed doors are provided at both ends of the cooling box to isolate the air, and protective gas is introduced into one end of the cooling box and discharged from the other end of the cooling box. The introduction of protective gas can increase the cooling speed of the tool and prevent oxidation of the tool surface. The protective gas is nitrogen. The cooling box can be a cooling box with a conveyor belt inside.

[0026] Among them, a first cooling fan is provided on the inner top plate at one end of the cooling box body close to the heating furnace, and a second cooling fan is provided on the inner top plate at the other end of the cooling box body to accelerate the flow rate of the protective gas to increase the cooling speed. A flow guide device is provided in the cooling box body to guide the flow of the protective gas. The flow guide device includes an arc-shaped air supply plate provided at one end of the cooling box body, which is used to introduce the above-mentioned protective gas into the interior of the cooling box body, and the lower end of the arc-shaped air supply plate blows air obliquely downward along the transmission direction of the tool. The flow guide device also includes an arc-shaped exhaust plate provided at the other end of the cooling box body, and the lower end of the arc-shaped exhaust plate exhausts air obliquely upward along the transmission direction of the tool to extract the protective gas in the cooling box body.

[0027] 3) The tool after cooling treatment in step 2) is tempered.

[0028] In step 3), the tempering temperature is 150°C.

[0029] Embodiment 2

[0030] A heat treatment method for a martensitic stainless steel tool comprises the following steps:

[0031] 1) The martensitic stainless steel tool is sent into a heating furnace for heating treatment;

[0032] In step 1), the temperature and time of the heating treatment can be selected according to the material and the different performance requirements of the enterprise. This embodiment will not be described in detail. The existing heating treatment temperature and time and adjustment can be referred to. A protective gas is introduced into the heating furnace to prevent oxidation of the tool. The heating furnace adopts an existing conveyor belt heating furnace. The protective gas adopts ethanol gas.

[0033] 2) the tool after the heating treatment in step 1) is sent into a cooling box;

[0034] In step 2), sealing doors are provided at both ends of the cooling box to isolate the air, and protective gas is introduced into one end of the cooling box and discharged from the other end of the cooling box. The introduction of protective gas can increase the cooling speed of the tool and prevent oxidation of the tool surface. The protective gas is ethanol gas. The cooling box can be a cooling box with a conveyor belt inside.

[0035] Among them, a first cooling fan is provided on the inner top plate at one end of the cooling box body close to the heating furnace, and a second cooling fan is provided on the inner top plate at the other end of the cooling box body to accelerate the flow rate of the protective gas to increase the cooling speed. A flow guide device is provided in the cooling box body to guide the flow of the protective gas. The flow guide device includes an arc-shaped air supply plate provided at one end of the cooling box body, which is used to introduce the above-mentioned protective gas into the interior of the cooling box body, and the lower end of the arc-shaped air supply plate blows air obliquely downward along the transmission direction of the tool. The flow guide device also includes an arc-shaped exhaust plate provided at the other end of the cooling box body, and the lower end of the arc-shaped exhaust plate exhausts air obliquely upward along the transmission direction of the tool to extract the protective gas in the cooling box body.

[0036] 3) The tool after cooling treatment in step 2) is tempered.

[0037] In step 3), the tempering temperature is 180°C.

[0038] Embodiment 3

[0039] A heat treatment method for a martensitic stainless steel tool comprises the following steps:

[0040] 1) The martensitic stainless steel tool is sent into a heating furnace for heating treatment;

[0041] In step 1), the temperature and time of the heating treatment can be selected according to the material and the different performance requirements of the enterprise. This embodiment will not be described in detail. The existing heating treatment temperature and time and adjustment can be referred to. A protective gas is introduced into the heating furnace to prevent oxidation of the tool. The heating furnace adopts the existing conveyor belt heating furnace. The protective gas adopts a mixed gas of nitrogen and ethanol gas.

[0042] 2) the tool after the heating treatment in step 1) is sent into a cooling box;

[0043] In step 2), sealed doors are provided at both ends of the cooling box to isolate the air, and protective gas is introduced into one end of the cooling box and discharged from the other end of the cooling box. The introduction of protective gas can increase the cooling speed of the tool and prevent oxidation of the tool surface. The protective gas is a mixed gas of nitrogen and ethanol gas. The cooling box can be a cooling box with a conveyor belt inside.

[0044] Among them, a first cooling fan is provided on the inner top plate at one end of the cooling box body close to the heating furnace, and a second cooling fan is provided on the inner top plate at the other end of the cooling box body to accelerate the flow rate of the protective gas to increase the cooling speed. A flow guide device is provided in the cooling box body to guide the flow of the protective gas. The flow guide device includes an arc-shaped air supply plate provided at one end of the cooling box body, which is used to introduce the above-mentioned protective gas into the interior of the cooling box body, and the lower end of the arc-shaped air supply plate blows air obliquely downward along the transmission direction of the tool. The flow guide device also includes an arc-shaped exhaust plate provided at the other end of the cooling box body, and the lower end of the arc-shaped exhaust plate exhausts air obliquely upward along the transmission direction of the tool to extract the protective gas in the cooling box body.

[0045] 3) The tool after cooling treatment in step 2) is tempered.

[0046] In step 3), the tempering temperature is 165°C.

[0047] The heat treatment device used in the heat treatment method in the above-mentioned embodiment 1 to embodiment 3 is as follows: Figure 1 As shown, it includes a heating furnace 1 and a cooling box 2, and both ends of the cooling box are provided with sealed doors 3. A first cooling fan 4 is arranged on the inner top plate of one end of the cooling box close to the heating furnace, and a second cooling fan 5 is arranged on the inner top plate of the other end of the cooling box to accelerate the flow rate of the protective gas to increase the cooling speed of the tool. A guide device is arranged in the cooling box to guide the flow of the protective gas. The guide device includes an arc-shaped air supply plate 6 arranged at one end of the cooling box, which is used to pass the above-mentioned protective gas into the interior of the cooling box, and the lower end of the arc-shaped air supply plate blows air obliquely downward along the transmission direction of the tool. An air supply pipe 7 connected to the arc-shaped air supply plate 6 is arranged on the cooling box. The guide device also includes an arc-shaped exhaust plate 8 arranged at the other end of the cooling box, and the lower end of the arc-shaped exhaust plate exhausts air obliquely upward along the transmission direction of the tool to extract the protective gas in the cooling box.

[0048] Comparative Example

[0049] A heat treatment method for a martensitic stainless steel tool is different from the first embodiment in that no protective gas is introduced into the heating furnace and the cooling box. In this case, the cooling box is not provided with a sealing door, a first cooling fan, a second cooling fan, and a flow guide device, that is, the cooling furnace in the background technology is used for air cooling.

[0050] Figure 2 The tool sample obtained after heat treatment in the comparative example has a microstructure as shown in Figure 3 As shown in the figure. The microstructure of the tool sample obtained in Example 1 is as follows: Figure 4As shown. It can be seen that the tool produced by the unimproved heat treatment method has a relatively serious pitting phenomenon, and there are obvious carbide particles precipitated along the grain boundaries in its microstructure, which seriously weakens the corrosion resistance of the grain boundaries. The heat treatment method used in this application has significantly improved its microstructure, reduced grain size, and uniformly dispersed carbides.

[0051] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A heat treatment method for martensitic stainless steel cutting tools, characterized in that: The following steps are involved: 1) The martensitic stainless steel tool is sent into a heating furnace for heating treatment; 2) the tool after the heating treatment in step 1) is sent into a cooling box; In step 2), sealed doors are provided at both ends of the cooling box to isolate the air, and protective gas is introduced into one end of the cooling box and discharged from the other end of the cooling box. The introduction of protective gas can increase the cooling speed of the tool and prevent oxidation of the tool surface.

2. The heat treatment method for martensitic stainless steel cutting tools according to claim 1, characterized in that: In step 2), a first cooling fan is provided on the inner top plate at one end of the cooling box body close to the heating furnace, and a second cooling fan is provided on the inner top plate at the other end of the cooling box body to accelerate the flow rate of the protective gas to increase the cooling speed of the tool.

3. The heat treatment method for martensitic stainless steel cutting tools according to claim 1, characterized in that: In step 2), a flow guide device is provided in the cooling box to guide the flow of the protective gas.

4. The heat treatment method for martensitic stainless steel cutting tools according to claim 3, characterized in that: The guide device includes an arc-shaped air supply plate arranged at one end of the cooling box, which is used to introduce the above-mentioned protective gas into the interior of the cooling box, and the lower end of the arc-shaped air supply plate blows air obliquely downward along the transmission direction of the tool; the guide device also includes an arc-shaped exhaust plate arranged at the other end of the cooling box, and the lower end of the arc-shaped exhaust plate draws air obliquely upward along the transmission direction of the tool to extract the protective gas in the cooling box.

5. The heat treatment method for martensitic stainless steel cutting tools according to claim 1, characterized in that: In step 2), the protective gas is selected from nitrogen gas, ethanol gas or a mixture of the two.

6. The heat treatment method for martensitic stainless steel cutting tools according to any one of claims 1 to 5, characterized in that: The tool after cooling treatment in step 2) is then tempered.

7. The heat treatment method for martensitic stainless steel cutting tools according to claim 6, characterized in that: The tempering temperature is 150-180℃.

8. The heat treatment method for martensitic stainless steel cutting tools according to claim 1, characterized in that: A protective gas is passed through the heating furnace to prevent the tool from being oxidized.

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