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A Control Method of Heat Treatment Deformation Based on Phase Change Plasticity

A heat treatment deformation and control method technology, which is applied in heat treatment process control, heat treatment equipment, manufacturing tools, etc., can solve the problems of large orthopedic force and long time, achieve low internal stress, qualified tissue hardness, and reduce costs

Active Publication Date: 2017-03-01
SHANGHAI JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] The purpose of the present invention is to provide a heat treatment deformation control method based on phase change plasticity in order to solve the problems of large orthopedic force and long time in the orthopedic work piece after heat treatment.

Method used

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  • A Control Method of Heat Treatment Deformation Based on Phase Change Plasticity

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Experimental program
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Effect test

Embodiment 1

[0037] The yield strength of 20MnTiB high-strength steel plate (9000×1500×5) can reach 960MPa after quenching + high temperature tempering. It is required that the flatness tolerance of the steel plate after heat treatment and correction is 4mm.

[0038] Step 1. Heating the whole steel plate to 880°C for austenitization for 60 minutes;

[0039]Step 2. The starting temperature Ms of 20MnTiB martensite is 410°C, so the upper and lower surfaces of the austenitic steel plate are sprayed with water curtains to quench to 350°C to ensure the uniformity of the upper and lower overall quenching;

[0040] Step 3, the quenched steel plate is straightened once by a 9-roller straightening machine. The reduction of the straightening roller is 2mm, and the stress under the straightening load is calculated to be about 300MPa;

[0041] Step 4. Cool the upper and lower surfaces of the orthopedic steel plate with water curtains to below 250°C;

[0042] Step 5. Put the steel plate in a temperi...

Embodiment 2

[0044] The aircraft landing gear made of 30CrMnSiNi2A steel has a yield strength of 1125MPa after nitrate isothermal quenching + low temperature tempering. It is required that the dimensional error of hydraulic orthopedics after heat treatment should not exceed 5%.

[0045] Step 1. Heating the whole part to 900°C for austenitization for 90 minutes;

[0046] Step 2. The bainite transformation temperature of 30CrMnSiNi2A steel is 270°C, so the fully austenitic parts are austempered to 270°C in nitrate and kept for 20 minutes;

[0047] Step 3. Take the parts out of the nitrate and place them in a hydraulic orthopedic machine to ensure that each size is corrected to the design size. The available orthopedic pressure is 572MPa, and the orthopedic time is controlled within 15 minutes to ensure that the temperature of the parts is not lower than 210°C. ;

[0048] Step 4: Return the orthopedic parts to nitrate at 270°C for 40 minutes, then take them out and cool them to room tempera...

Embodiment 3

[0051] No. 45 steel plate (size 9000×1500×4) has a yield strength of 335MPa after quenching and tempering treatment. It is required that the flatness tolerance of the steel plate after heat treatment and correction is 4mm.

[0052] Step 1. Heating the whole steel plate to 840°C for austenitization for 50 minutes;

[0053] Step 2. Spray water on the upper and lower surfaces of the fully austenitized steel plate and quench it to room temperature to ensure the uniformity of the upper and lower overall quenching;

[0054] Step 3. Quickly move the quenched steel plate to the straightening machine for one pass of straightening. The time between the end of quenching and the beginning of straightening should not exceed 15 minutes. The orthopedic load is applied, and the achieved stress is about 230MPa;

[0055] Step 4: Put the corrected steel plate in a tempering furnace, hold the tempering temperature at 600° C. for 45 minutes, and then air-cool it to room temperature to obtain a s...

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Abstract

The invention relates to a control method of a heat treatment distortion based on a phase transformation plasticity. The control method of the heat treatment distortion based on the phase transformation plasticity comprises an austenitizing procedure, a quenching procedure, a shape-correcting procedure under the phase transformation plasticity, and a tempering procedure. Additionally, a procedure of keeping quenching can be added as need between the shape-correcting procedure under the phase transformation plasticity and the tempering procedure. Comparing to the prior art, the control method of the heat treatment distortion based on the phase transformation plasticity effectively solves the problems that a large load and a long time are required for correcting shapes of workpieces after the heat treatment; and the control method of the heat treatment distortion based on the phase transformation plasticity reduces the control cost of the heat treatment distortion. Additionally, the control method of the heat treatment distortion based on the phase transformation plasticity can be applied to occasions of high-strength steel plates, parts of complex shapes, and large-scale thin-walled structural components that are large and hard to control in heat treatment distortions, or shapes are difficult to be corrected after the heat treatment. Different phase transformation plasticity shape-correcting technologies can be applied to different materials.

Description

technical field [0001] The invention relates to a metal material processing technology, in particular to a method for controlling heat treatment deformation based on phase change plasticity. Background technique [0002] Mechanical parts of metal products can usually be heat treated to improve their mechanical properties. In the process of heat treatment, due to factors such as material inhomogeneity, heating and cooling inhomogeneity, and residual stress, the parts to be processed usually have different degrees of bending and warping, which are called heat treatment deformation. If the metal parts that undergo heat treatment deformation exceed a certain range, they usually need to be corrected to make their size meet the design requirements. The orthopedic principle of heat-treated deformed parts is a processing technology that causes a small amount of plastic deformation of the material under the action of an external force and permanently retains this part of the deforma...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D1/18C21D11/00
CPCC21D1/18C21D1/20C21D7/10C21D11/00
Inventor 仝大明顾剑锋
Owner SHANGHAI JIAOTONG UNIV
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