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Method for refining grains of large medium high alloy steel forgings

A technology for large-scale forgings and grain refinement, applied in heat treatment equipment, heat treatment process control, manufacturing tools, etc., can solve the problems of coarse grains and mixed grains, unstable grain refining effect of large-scale forgings, etc., and achieve a simple operation process. Easy to operate, reduce energy and time cost consumption, refine the effect with remarkable effect

Inactive Publication Date: 2012-10-31
SHANGHAI JIAOTONG UNIV
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Problems solved by technology

[0008] Aiming at the above-mentioned deficiencies in the prior art, the present invention provides a grain refinement method for large-scale forgings of medium-high alloy steel, which solves the problem of unstable grain refinement effect of large-scale forgings caused by traditional multiple normalizing processes in actual production, and coarse grains. and the serious problem of mixed crystal phenomenon

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  • Method for refining grains of large medium high alloy steel forgings
  • Method for refining grains of large medium high alloy steel forgings
  • Method for refining grains of large medium high alloy steel forgings

Examples

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Effect test

Embodiment 1

[0032] The test uses 30Cr2Ni4MoV steel commonly used for large forgings of low pressure rotors, and its original grain size is about ASTM No.1.0 grade, see figure 1 The chemical composition is shown in Table 1, and the test material was processed into a 15mm×15mm×15mm sample. First, the sample was heated from room temperature to 840 °C at a heating rate of 30 °C / h, and kept for 3 h; then, the sample was cooled to a pearlite transition nose tip temperature of 600 °C at a rate of 50 °C / h, and kept for 120 h to generate a certain amount of Reticular distribution of pearlite tissue (such as figure 2 ) to eliminate the inheritance of the structure, and then cooled to room temperature; then, the sample was heated to 870 °C at a heating rate of 30 °C / h, and kept for 3 h to make the austenitization uniform, and recrystallized fine particles through austenitization. crystallized grains, then cooled to room temperature, grain size see image 3 shown. The test results show that the m...

Embodiment 2

[0036] The test uses 30Cr2Ni4MoV steel commonly used for large forgings of low pressure rotors, and its original grain size is about ASTM No.1.0 grade, see figure 1 The chemical composition is shown in Table 1, and the test material was processed into a 15mm×15mm×15mm sample. First, the sample was heated from room temperature to 840°C at a heating rate of 30°C / h, and kept for 3 hours; then, the sample was cooled to a pearlite transition nose tip temperature of 600°C at a rate of 50°C / h, and kept for 240 hours to generate a certain amount of Reticular distribution of pearlite tissue (such as Figure 4 ) to eliminate the inheritance of the structure, and then cooled to room temperature; then, the sample was heated to 870 °C at a heating rate of 30 °C / h, and kept for 3 h to make the austenitization uniform, and recrystallized fine particles through austenitization. crystallized grains, then cooled to room temperature, grain size see Figure 5 shown. The test results show that ...

Embodiment 3

[0038] The test uses 30Cr2Ni4MoV steel commonly used for large forgings of low pressure rotors, and its original grain size is about ASTM No.1.0 grade, see figure 1 The chemical composition is shown in Table 1, and the test material was processed into a 15mm×15mm×15mm sample. First, the sample was heated from room temperature to 840 °C at a heating rate of 30 °C / h, and kept for 3 h; then, the sample was cooled to a pearlite transition nose tip temperature of 600 °C at a rate of 50 °C / h, and kept for 360 h to generate a certain amount of Reticular distribution of pearlite tissue (such as Image 6 ) to eliminate the inheritance of the structure, and then cooled to room temperature; then, the sample was heated to 870 °C at a heating rate of 30 °C / h, and kept for 3 h to make the austenitization uniform, and recrystallized fine particles through austenitization. crystallized grains, then cooled to room temperature, grain size see Figure 7 shown. The test results show that the m...

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Abstract

The invention discloses a method for refining grains of large medium high alloy steel forgings in the technical field of metal heat treatment. The method comprises the following steps of: austenitizing the forged forgings, cooling to tip temperature of a perlitic transformation area, and isothermally keeping temperature or fluctuantly keeping temperature to realizing isothermal decomposition of pearlite; and cooling to room temperature, and performing the secondary austenitizing process to realize recrystallization to refine the grains again. The method solves the problem that the traditionalmultiple normalizing process in actual production has instable effect of refining the grains of the large forgings, and a serious phenomena of coarse grains and mixed grains. By incomplete isothermalbalanced decomposition of austenite, structure inheritance is cut off and eliminated, average austenite grain size above ASTM No.5 grade is achieved, the structure state of the large forgings is improved, the ultrasonic inspectability of the large forgings is improved; meanwhile, working hours are greatly shortened, the energy consumption is reduced, and the cost is saved.

Description

technical field [0001] The invention relates to a method in the technical field of metal heat treatment, in particular to a grain refinement method for large forgings of medium and high alloy steel. Background technique [0002] Large-scale forgings are load-bearing and transmission structural components in nuclear power, thermal power and other power plant equipment and large-scale metallurgical, mining and transportation equipment. They are core components and the basis for the reliable operation of equipment. The large-scale equipment also makes the forgings larger, especially under the guidance of the design concept of improving efficiency, reducing consumption, safety and reliability, in addition to using a large number of high-alloy steel, the original combined components that were assembled through subsequent assembly are also integrated. The size and weight of single forgings increase dramatically. In the main equipment of nuclear power, thermal power, hydropower an...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D11/00C21D1/18
Inventor 顾剑锋陈睿恺韩利战潘健生
Owner SHANGHAI JIAOTONG UNIV
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