A treatment method for reducing coarse or network carbides in high-carbon martensitic stainless steel and its application

Abstract

The present invention provides a treatment method and application thereof for reducing coarse or network carbides in high carbon martensitic stainless steel. The treatment method comprises the following steps: S1. rough rolling the high carbon martensitic stainless steel ingot at 1100-1200°C and keeping it warm for 2-4 hours to obtain an intermediate ingot; S2. high temperature solid solution of the intermediate ingot: placing the intermediate ingot in a protective atmosphere environment in a high temperature furnace at 1200-1250°C for insulation for 3-5 hours, and cooling. The present invention firstly crushes the network carbides and large particle carbides in the high carbon martensitic stainless steel ingot by rough rolling or hot forging to obtain an intermediate ingot, and then dissolves the soluble carbides in the intermediate ingot into austenite by high temperature solid solution, thereby reducing coarse or network carbides.

Description

Technical Field

[0001] The invention relates to the technical field of steel production, and more specifically to a treatment method for reducing coarse or network carbides in high-carbon martensitic stainless steel and an application thereof. Background Art

[0002] High carbon martensitic stainless steel is mainly used in the fields of knives, molds, bearing rings, bearing rolling elements, surgical instruments, etc. The matrix of this type of product contains a high carbon content, and it is easy to produce eutectic carbides, coarse carbides and network carbides during the solidification process, which has a great impact on subsequent processing. For example, large cracks may appear during the hot rolling process, resulting in the scrapping of the hot-rolled plate; or it may have a negative impact on the final product. For example, the prior art "9Cr18MoV High Carbon Martensitic Stainless Steel Mold Fracture Failure Analysis" mentioned that the mold made of 9Cr18MoV cracked during use. After analysis, it was found that the matrix structure was tempered martensite and residual austenite, with large eutectic carbides and granular secondary carbides distributed.

[0003] In order to solve the above problems, the prior art discloses a method for improving the carbides of high-carbon martensitic stainless steel. The method dissolves the liquid carbides between 10 μm and 100 μm in austenite at high temperature by keeping the temperature at 1200°C to 1300°C for 6 to 40 hours under argon protection. However, this method has obvious problems. From a thermodynamic point of view, the liquid carbides cannot be dissolved in austenite, and there is no corresponding experimental data recorded to prove that the carbides can be effectively eliminated. Secondly, the insulation time of the prior art is relatively long, which is difficult to use in industrial production. Summary of the invention

[0004] In order to overcome the coarse carbides and network carbides generated in the solidification process of high carbon martensitic stainless steel, the present invention provides a treatment method for reducing the coarse or network carbides of high carbon martensitic stainless steel.

[0005] Another object of the present invention is to provide application of the processing method.

[0006] Another object of the present invention is to provide a method for producing high carbon martensitic stainless steel.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0009] S1. Rough rolling: The high carbon martensitic stainless steel ingot is subjected to rough rolling at 1100-1200°C and kept at this temperature for 2-4 hours to obtain an intermediate ingot;

[0010] S2. High-temperature solid solution of the intermediate billet: The intermediate billet is placed in a high-temperature furnace at 1200-1250° C. in a protective atmosphere for 3-5 hours and then cooled.

[0011] The treatment method of the present invention uses two stages to treat high-carbon martensitic stainless steel. The first stage is to obtain an intermediate billet by rough rolling, the purpose of which is to crush network carbides and large-particle carbides; the second stage is to dissolve soluble carbides in austenite by high-temperature solid solution, effectively reducing the coarse or network carbides of high-carbon martensitic stainless steel. The present invention first crushes the network carbides and large-particle carbides in the high-carbon martensitic stainless steel ingot by rough rolling to obtain an intermediate billet, and then dissolves the crushed carbides in the intermediate billet into austenite by high-temperature solid solution, thereby reducing the coarse or network carbides.

[0012] Rough rolling refers to rolling the ingot to a thickness 5-15 times that of the final product specification. The rolling reduction and rolling passes are determined according to the specific production process.

[0013] Furthermore, the mass percentage of carbon in the high carbon martensitic stainless steel ingot is greater than or equal to 0.50%.

[0014] Furthermore, the mass percentage of carbon in the high carbon martensitic stainless steel ingot is 0.50-1.1%.

[0015] The mass percentage of carbon in the high carbon martensitic stainless steel ingot of the present invention is 0.45-1.1%, the mass percentage of chromium is 12.5-18.5%, the mass percentage of manganese is 0.40-0.60%, and the mass percentage of silicon is 0.40-0.60%.

[0016] The high carbon martensitic stainless steel ingot of the present invention is one or more of 5Cr15, 5Cr15MoV, 7Cr17, 7Cr17MoV, 8Cr13, 8Cr17, 8Cr17MoV, 9Cr18, 9Cr18MoV and 9Cr18Mo series steel grades.

[0017] Specifically, the mass percentage of carbon in the 5Cr15 of the present invention is 0.45-0.60%, and the mass percentage of chromium is 14.5-16.0%.

[0018] The mass percentage of carbon in the 5Cr15MoV of the present invention is 0.45-0.60%, the mass percentage of chromium is 14.5-16.0%, the mass percentage of molybdenum is 0.50-0.80%, and the mass percentage of vanadium is 0.10-0.20%.

[0019] The mass percentage of carbon in the 7Cr17 of the present invention is 0.60-0.75%, and the mass percentage of chromium is 16.5-18.0%.

[0020] The mass percentage of carbon in the 7Cr17MoV of the present invention is 0.60-0.75%, the mass percentage of chromium is 16.0-18.0%, the mass percentage of molybdenum is 0.50-0.80%, and the mass percentage of vanadium is 0.10-0.15%.

[0021] The mass percentage of carbon in the 8Cr13 of the present invention is 0.76-0.85%, and the mass percentage of chromium is 12.5-14.0%.

[0022] The mass percentage of carbon in the 8Cr17 of the present invention is 0.76-0.85%, and the mass percentage of chromium is 16.0-18.0%.

[0023] The mass percentage of carbon in the 8Cr17MoV of the present invention is 0.76-0.85%, the mass percentage of chromium is 16.0-18.0%, the mass percentage of molybdenum is 0.50-0.80%, and the mass percentage of vanadium is 0.10-0.15%.

[0024] The mass percentage of carbon in the 9Cr18 of the present invention is 0.90-1.0%, and the mass percentage of chromium is 17.0-19.0%.

[0025] The mass percentage of carbon in the 9Cr18MoV of the present invention is 0.90-1.0%, the mass percentage of chromium is 17.0-19.0%, the mass percentage of molybdenum is 0.50-0.80%, and the mass percentage of vanadium is 0.10-0.15%.

[0026] The mass percentage of carbon in the 9Cr18Mo is 0.90-1.0%, the mass percentage of chromium is 17.0-18.5%, and the mass percentage of molybdenum is 0.50-0.80%.

[0027] The high carbon martensitic stainless steel casting blank of the present invention is a continuous casting blank or a die casting ingot.

[0028] The present invention obtains an intermediate billet by rough rolling a martensitic stainless steel ingot. Generally, the thickness of the intermediate billet is 5-15 times the thickness of the final product. Then, the intermediate billet is subjected to high-temperature solid solution treatment, which can greatly reduce the presence of coarse carbides.

[0029] Furthermore, the protective atmosphere during the high-temperature solution treatment process is determined according to the actual equipment, including but not limited to N2 atmosphere and vacuum environment.

[0030] Furthermore, the cooling method after high-temperature solution can be flexibly selected according to site facilities, including but not limited to furnace cooling, air cooling, oil cooling, and water cooling.

[0031] Application of the treatment method of the present invention in the preparation of high carbon martensitic stainless steel.

[0032] A method for producing high carbon martensitic stainless steel includes the above treatment method. The coarse or network carbides in the high carbon martensitic stainless steel can be effectively reduced by the treatment method of the present invention.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The treatment method of the present invention uses two stages to treat high-carbon martensitic stainless steel. The first stage is to obtain an intermediate billet through rough rolling, the purpose of which is to crush network carbides and large-particle carbides; the second stage is to dissolve soluble carbides in austenite through high-temperature solid solution, effectively reducing coarse or network carbides in high-carbon martensitic stainless steel. The treatment method of the present invention does not require new equipment investment, and has strong feasibility and good continuity in production operation. After high-temperature solid solution treatment, it has a positive effect on subsequent rolling, and is very suitable for wide promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a metallographic picture of 8Cr17MoV high carbon martensitic stainless steel die-cast ingot.

[0036] Figure 2 This is a metallographic picture of 5Cr15MoV high carbon martensitic stainless steel die-cast ingot.

[0037] Figure 3 This is a metallographic picture of 9Cr18Mo high carbon martensitic stainless steel die-cast ingot.

[0038] Figure 4 This is a metallographic picture of 8Cr17MoV high carbon martensitic stainless steel after being treated in Example 1.

[0039] Figure 5 This is a metallographic picture of 8Cr17MoV high carbon martensitic stainless steel after being treated in Example 2.

[0040] Figure 6 This is a metallographic picture of 5Cr15MoV high carbon martensitic stainless steel after being treated in Example 3.

[0041] Figure 7 This is a metallographic picture of 9Cr18Mo high carbon martensitic stainless steel after being treated in Example 4.

[0042] Figure 8 This is a metallographic picture of 8Cr17MoV high carbon martensitic stainless steel after being treated in Comparative Example 1. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with specific embodiments. The raw materials in the embodiments and comparative examples can be obtained commercially or can be prepared by known methods. In addition, "parts" and "%" in this specification, unless otherwise specified, represent "parts by weight" and "mass %" respectively.

[0044] Condition of high carbon martensitic stainless steel before treatment:

[0045] 1) 8Cr17MoV high carbon martensitic stainless steel die-cast ingot, size: length 1500mm, big end 280×280mm, small end 180×180mm;

[0046] like Figure 1 As shown, the coarse or network carbides in the 8Cr17MoV high carbon martensitic stainless steel die-cast ingot: the as-cast structure of 8Cr17MoV, in which a large number of obvious network carbides are distributed.

[0047] 2) 5Cr15MoV high carbon martensitic stainless steel die casting ingot, size: length 1500mm, large end 280×280mm, small end 180×180mm; Figure 2 As shown, the coarse or network carbides in the 5Cr15MoV high carbon martensitic stainless steel die-cast ingot: the as-cast structure of 5Cr15MoV, in which obvious network carbides are distributed.

[0048] 3) 9Cr18Mo high carbon martensitic stainless steel die-cast ingot, size: length 1500mm, large end 280×280mm, small end 180×180mm;

[0049] like Figure 3 As shown, the coarse or network carbides in the 9Cr18Mo high carbon martensitic stainless steel die-cast ingot are as follows: the as-cast structure of 9Cr18MoV, in which a large number of obvious network carbides are distributed.

[0050] Example 1

[0051] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0052] S1. Rough rolling: 8Cr17MoV high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0053] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1200°C for 4 hours in a high-temperature furnace under a protective atmosphere and air-cooled.

[0054] Example 2

[0055] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0056] S1. Rough rolling: 8Cr17MoV high carbon martensitic stainless steel die-cast ingots were selected, kept at 1200℃ for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm.

[0057] S2. High temperature solid solution of the intermediate billet: The obtained intermediate billet is placed in a protective atmosphere environment, kept at 1250°C in a high temperature furnace for 4 hours, and water-cooled.

[0058] Example 3 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0059] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0060] S1. Rough rolling: 5Cr15MoV high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 2h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0061] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1250°C in a high-temperature furnace for 3 hours under a protective atmosphere and air-cooled.

[0062] Example 4 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0063] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0064] S1. Rough rolling: 9Cr18Mo high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1200°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0065] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1250°C in a high-temperature furnace for 5 hours under a protective atmosphere and air-cooled.

[0066] Example 5 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0067] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0068] S1. Rough rolling: 5Cr15 high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0069] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1200°C for 4 hours in a high-temperature furnace under a protective atmosphere and air-cooled.

[0070] Example 6 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0071] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0072] S1. Rough rolling: 7Cr17 high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0073] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1200°C for 4 hours in a high-temperature furnace under a protective atmosphere and air-cooled.

[0074] Example 7 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0075] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0076] S1. Rough rolling: 7Cr17MoV high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0077] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1200°C for 4 hours in a high-temperature furnace under a protective atmosphere and air-cooled.

[0078] Example 8 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0079] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0080] S1. Rough rolling: 8Cr13 high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0081] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1200°C for 4 hours in a high-temperature furnace under a protective atmosphere and air-cooled.

[0082] Example 9 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0083] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0084] S1. Rough rolling: 8Cr17 high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0085] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1200°C for 4 hours in a high-temperature furnace under a protective atmosphere and air-cooled.

[0086] Example 10 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0087] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0088] S1. Rough rolling: 9Cr18 high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0089] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1200°C for 4 hours in a high-temperature furnace under a protective atmosphere and air-cooled.

[0090] Example 11 (Different types of high carbon martensitic stainless steel die-cast ingots)

[0091] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0092] S1. Rough rolling: 9Cr18MoV high carbon martensitic stainless steel die-cast ingots were selected, the high carbon martensitic stainless steel die-cast ingots were kept at 1100°C for 4h, and then rough rolled to finally obtain an intermediate billet with a thickness of 32mm;

[0093] S2. High-temperature solid solution of the intermediate billet: The obtained intermediate billet is kept at 1200°C for 4 hours in a high-temperature furnace under a protective atmosphere and air-cooled.

[0094] Comparative Example 1 (without rough rolling)

[0095] A method for reducing coarse or network carbides in high carbon martensitic stainless steel comprises the following steps:

[0096] 8Cr17MoV high carbon martensitic stainless steel die-cast ingot was selected, and the high carbon martensitic stainless steel die-cast ingot was kept at 1250°C for 4 hours in a protective atmosphere environment and then air-cooled.

[0097] test

[0098] The metallographic inspection surface of the samples prepared in the above embodiments and comparative examples was placed under an optical microscope to take metallographic pictures. The metallographic pictures of each embodiment and comparative example are shown in FIG. Figures 1 to 8 As shown in Table 1 below:

[0099] Table 1

[0100]

[0101]

[0102] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for reducing the network carbides generated during the solidification process of high carbon martensitic stainless steel, characterized in that: The following steps are involved: S1. Rough rolling: The high carbon martensitic stainless steel ingot is subjected to rough rolling at 1100-1200°C and kept at this temperature for 2-4 hours to obtain an intermediate billet; the thickness of the intermediate billet is 31-33 mm; the thickness of the intermediate billet is 5-15 times the thickness of the final product; S2. High-temperature solid solution of the intermediate billet: the intermediate billet is placed in a high-temperature furnace at 1200-1250°C in a protective atmosphere for insulation for 3-5 hours, and then cooled; the 1200-1250°C does not include 1200°C.

2. The processing method according to claim 1, characterized in that: The mass percentage of carbon in the high carbon martensitic stainless steel ingot is greater than or equal to 0.45%.

3. The processing method according to claim 2, characterized in that: The mass percentage of carbon in the high carbon martensitic stainless steel ingot is 0.45-1.1%.

4. The processing method according to claim 3, characterized in that: The mass percentage of chromium in the high carbon martensitic stainless steel ingot is 12.5-18.5%, the mass percentage of manganese is 0.40-0.60%, and the mass percentage of silicon is 0.40-0.60%.

5. The processing method according to claim 1 or 4, characterized in that: The high carbon martensitic stainless steel is one or more of the series of steels of 5Cr15, 5Cr15MoV, 7Cr17, 7Cr17MoV, 8Cr17, 8Cr13, 8Cr17MoV, 9Cr18, 9Cr18MoV and 9Cr18Mo.

6. The processing method according to claim 1, characterized in that: The high carbon martensitic stainless steel ingot is a continuous casting ingot or a die casting ingot.

7. Use of the treatment method according to any one of claims 1 to 6 in the preparation of high carbon martensitic stainless steel.

8. A method for producing high carbon martensitic stainless steel, characterized in that: The method comprises the treatment method according to any one of claims 1 to 6.

9. A high carbon martensitic stainless steel obtained by the production method according to claim 8.

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