Heat treatment method for eliminating high alloy steel forging network carbide
Through segmented insulation and high-temperature slow heating processes, the problem of difficult to eliminate mesh carbides in high alloy steel forging is solved, and the complete elimination of small grain sizes and energy savings are achieved, and production costs are reduced.
Patent Information
- Application Number
- CN202411438736.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-15
- Publication Date
- 2025-01-17
AI Technical Summary
The mesh carbides produced during the forging of high alloy steel are difficult to completely eliminate. Traditional high-temperature treatment methods will lead to an increase in grain size and reduce material performance.
The segmented insulation and high-temperature slow heating process are adopted to dissolve step by step according to the dissolution temperature of different types of carbides, and the treatment is short-term high-temperature to avoid the growth of grains and ensure the complete elimination of the mesh carbides. Specific steps include: heating to 1050 to 1065℃/min for 20 to 30 minutes, heating to 1120 to 1160℃ for 5 to 10 minutes, and then cooling to room temperature quickly.
On the premise of ensuring small grain size, the network carbides distributed along the grain boundary after forging are completely eliminated, energy saving and production costs are reduced.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to a heat treatment method for eliminating forged network carbides of high alloy steel, belonging to the technical field of heat treatment. Background Art
[0002] High alloy steel is a high-performance special service material developed to adapt to the special service environment and structural complexity of aerospace, petrochemical, mining machinery, processing and manufacturing. Compared with medium and low alloy steels, high alloy steel has higher high temperature stability, good corrosion resistance, and high wear resistance and fatigue resistance. The high alloy element content is the key to the excellent comprehensive performance of this type of material. The addition of strengthening elements such as Cr, Co, Mo and W can not only significantly improve the wear resistance and fatigue resistance of steel, but also significantly improve the corrosion resistance and high temperature stability of steel materials, and can produce secondary hardening and grain refinement to ensure that the steel has a certain toughness. However, in high alloy steel, the content of alloy elements is high. While improving the service performance of steel, large-sized carbides will inevitably be produced. Especially after the forging process is completed and annealed, the carbides in the material organization are distributed in a network at the grain boundaries, so high temperature treatment is required to eliminate the network organization. The conventional heat treatment method to eliminate network carbides is to keep the temperature at around 1060°C, but the carbides cannot be completely dissolved near this temperature and the size of the undissolved carbides is relatively large; when the temperature is raised to around 1120°C, the carbides are basically completely dissolved, but at this temperature and above, the grain size will increase, resulting in a decrease in performance. Summary of the invention
[0003] In view of the technical problem that the network structure of high-alloy steel is difficult to eliminate, the present invention proposes a heat treatment method for eliminating network carbides in high-alloy steel forging, that is, through a segmented heat preservation and high-temperature slow heating process, the network carbides are dissolved step by step according to the dissolution temperature of different types of carbides, and the residence time at high temperature is short, and the grain growth is not obvious; compared with the existing heat treatment method for eliminating network carbides, the network carbides distributed along the grain boundaries after forging can be completely eliminated while ensuring a smaller grain size.
[0004] A heat treatment method for eliminating forging network carbides of high alloy steel, the specific steps are as follows:
[0005] (1) heating the high alloy forging steel billet to 1050-1065°C at a heating rate of 5-15°C / min and keeping the temperature for 20-30 min;
[0006] (2) heating the high alloy forging steel billet treated in step (1) to a preset temperature of 1120-1160° C. at a heating rate of 1-3° C. / min and keeping the temperature for 5-10 min;
[0007] (3) The high alloy forging steel billet kept warm in step (2) is rapidly cooled to room temperature at a rate of 1.5 to 20°C / s.
[0008] In terms of mass percentage, the C content in the high alloy forging steel billet of step (1) is 0.1-0.15%, the total content of alloying elements is 29-36%, the total content of impurity elements P and S is not more than 0.02%, and the rest is Fe.
[0009] The principle of eliminating network carbides in high-alloy steel forging: Through segmented insulation and high-temperature slow heating process, the network carbides are dissolved step by step according to the dissolution temperature of different types of carbides. The undissolved carbides in the high-temperature slow heating process can hinder the growth of grains. The residence time at high temperature is short, and the grain growth is not obvious. The network carbides distributed along the grain boundaries after forging can be completely eliminated while ensuring a smaller grain size.
[0010] The beneficial effects of the present invention are:
[0011] Compared with the traditional high-temperature treatment method for eliminating carbides, the present invention uses a segmented heat preservation and high-temperature slow heating process to completely eliminate the network carbides distributed along the grain boundaries after forging while ensuring a smaller grain size. The heat preservation time in the high-temperature stage is shorter, which can save energy consumption and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Figure 1 Heat treatment process diagram for eliminating network carbides in high alloy steel forging;
[0013] Figure 2 It is the process diagram of comparative example 1;
[0014] Figure 3 It is the process diagram of comparative example 2;
[0015] Figure 4 This is the scanned organization diagram after heat treatment of Example 1;
[0016] Figure 5 This is the scanned organization diagram after heat treatment of Example 2;
[0017] Figure 6 This is the scanned organization diagram after heat treatment of Example 3;
[0018] Figure 7 This is the scanning organization diagram after heat treatment of comparative example 1;
[0019] Figure 8 This is the scanning organization diagram after heat treatment of comparative example 2;
[0020] Fig. 9 It is a comparison chart of the average grain size of Examples 1 to 3 and Comparative Examples 1 to 2. DETAILED DESCRIPTION
[0021] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.
[0022] The alloy composition of the high alloy forging steel billet in the embodiment of the present invention is as follows: in terms of mass percentage, the C content in the high alloy forging steel billet is 0.1-0.15%, the total content of alloy elements is 29-36%, the total content of impurity elements P and S is not more than 0.02%, and the rest is Fe.
[0023] Example 1: A heat treatment method for eliminating high alloy steel forging network carbides (see Figure 1 ), the specific steps are as follows:
[0024] (1) heating a high alloy forging steel billet with a diameter of 100 mm to 1050° C. at a heating rate of 5° C. / min and keeping the temperature for 20 min; the alloy composition of the high alloy forging steel billet is as follows: in terms of mass percentage, the C content in the high alloy forging steel billet is 0.1%, the total content of alloy elements is 29%, the total content of impurity elements P and S is not more than 0.02%, and the remainder is Fe;
[0025] (2) heating the high alloy forging steel billet treated in step (1) to a preset temperature of 1120° C. at a heating rate of 1° C. / min and keeping the temperature for 5 min;
[0026] (3) rapidly cooling the high alloy steel forging billet kept warm in step (2) to room temperature at a rate of 1.5° C. / s;
[0027] through Figure 1 After the heat treatment process shown in the figure, the SEM microstructure photograph is as follows: Figure 4 The average grain size is shown in Fig. 9 As shown in the figure, after the heat treatment process for eliminating the network carbides in high alloy steel forging, the network carbides distributed along the grain boundaries have been completely eliminated, and the average grain size is 38.2μm.
[0028] Example 2: A heat treatment method for eliminating high alloy steel forging network carbides (see Figure 1 ), the specific steps are as follows:
[0029] (1) heating a high alloy forging steel billet with a diameter of 100 mm to 1060° C. at a heating rate of 10° C. / min and keeping the temperature for 25 min; the alloy composition of the high alloy forging steel billet is as follows: in terms of mass percentage, the C content in the high alloy forging steel billet is 0.128%, the total content of alloy elements is 32.4%, the total content of impurity elements P and S is not more than 0.02%, and the rest is Fe;
[0030] (2) heating the high alloy forging steel billet treated in step (1) to a preset temperature of 1140° C. at a heating rate of 2° C. / min and keeping the temperature for 8 min;
[0031] (3) rapidly cooling the high alloy steel forging billet kept warm in step (2) to room temperature at a rate of 12° C. / s;
[0032] through Figure 1 After the heat treatment process shown in the figure, the SEM microstructure photograph is as follows: Figure 5 As shown, the grain size is Fig. 9 As shown in the figure, after the heat treatment process for eliminating the network carbides in high alloy steel forging, the network carbides distributed along the grain boundaries have been completely eliminated, and the average grain size is 40.7μm.
[0033] Example 3: A heat treatment method for eliminating high alloy steel forging network carbides (see Figure 1 ), the specific steps are as follows:
[0034] (1) heating a high alloy forging steel billet with a diameter of 100 mm to 1065° C. at a heating rate of 15° C. / min and keeping the temperature for 30 min; the alloy composition of the high alloy forging steel billet is as follows: in terms of mass percentage, the C content in the high alloy forging steel billet is 0.15%, the total content of alloy elements is 36%, the total content of impurity elements P and S is not more than 0.02%, and the rest is Fe;
[0035] (2) heating the high alloy forging steel billet treated in step (1) to a preset temperature of 1160° C. at a heating rate of 3° C. / min and keeping the temperature for 10 min;
[0036] (3) rapidly cooling the high alloy steel forging billet kept warm in step (2) to room temperature at a rate of 20° C. / s;
[0037] through Figure 1 After the heat treatment process shown in the figure, the SEM microstructure photograph is as follows: Figure 6 As shown, the grain size is Fig. 9 As shown in the figure, after the heat treatment process for eliminating the network carbides in high alloy steel forging, the network carbides distributed along the grain boundaries have been completely eliminated, and the average grain size is 44.3μm.
[0038] Comparative Example 1: Heat treatment method for eliminating network carbides (see Figure 2 ), the specific steps are as follows:
[0039] (1) heating a high alloy forging steel billet with a diameter of 100 mm to 1060° C. at a heating rate of 10° C. / min and keeping the temperature for 60 min; the alloy composition of the high alloy forging steel billet is as follows: in terms of mass percentage, the C content in the high alloy forging steel billet is 0.1%, the total content of alloy elements is 29%, the total content of impurity elements P and S is not more than 0.02%, and the rest is Fe;
[0040] (2) cooling the high alloy forging steel billet subjected to the insulation treatment in step (1) to room temperature at a rate of 12° C. / s;
[0041] Comparative Example 1: Scanning diagram of heat treatment structure for eliminating network carbides in high alloy steel forging Figure 7 ,from Figure 7 It can be seen that the network carbides distributed along the grain boundaries are only partially dissolved into the matrix and are not completely eliminated; the average grain size of Comparative Example 1 is shown in FIG. Fig. 9 The average grain size is 35.7 μm. Although the grains have not grown, the carbides have not been completely eliminated.
[0042] Comparative Example 2: Heat treatment method for eliminating network carbides (see Figure 3 ), the specific steps are as follows:
[0043] (1) heating a high alloy forging steel billet with a diameter of 100 mm to 1160° C. at a heating rate of 10° C. / min and keeping the temperature for 40 min; the alloy composition of the high alloy forging steel billet is as follows: in terms of mass percentage, the C content in the high alloy forging steel billet is 0.15%, the total content of alloy elements is 36%, the total content of impurity elements P and S is not more than 0.02%, and the remainder is Fe;
[0044] (2) cooling the high alloy forging steel billet subjected to the insulation treatment in step (1) to room temperature at a rate of 20° C. / s;
[0045] Comparative Example 2: Scanning diagram of heat treatment structure for eliminating network carbides in high alloy steel forging Figure 8 ,from Figure 8 It can be seen that the network carbides distributed along the grain boundaries have all dissolved into the matrix, but the average grain size is 79.6 μm and the grains are severely coarsened.
[0046] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.
Claims
1. A heat treatment method for eliminating network carbides in high alloy steel forging, characterized in that: The specific steps are as follows: (1) heating the high alloy forging steel billet to 1050-1065°C at a heating rate of 5-15°C / min and keeping the temperature for 20-30 min; (2) heating the high alloy forging steel billet treated in step (1) to a preset temperature of 1120-1160° C. at a heating rate of 1-3° C. / min and keeping the temperature for 5-10 min; (3) The high alloy forging steel billet kept warm in step (2) is cooled to room temperature at a rate of 1.5 to 20°C / s.
2. The heat treatment method for eliminating forging network carbides of high alloy steel according to claim 1, characterized in that: In terms of mass percentage, the C content in the high alloy forging steel billet of step (1) is 0.1-0.15%, the total content of alloying elements is 29-36%, the total content of impurity elements P and S is not more than 0.02%, and the rest is Fe.