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An optimization method of water quenching process for alloy steel
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An optimization method, technology of alloy steel
Active Publication Date: 2019-12-24
SHANGHAI JIAO TONG UNIV
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Abstract
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Problems solved by technology
For alloy steel quenching, oil is generally used as the quenching medium to avoid cracking. The problem is that the mechanical properties of oil quenching are much lower than that of water quenching. At the same time, oil quenching has the risk of oil smokepollution and fire.
However, for large-sized medium-low hardenability alloy steel, the performance part is required to be in the deep part, and this process cannot meet the requirements.
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Embodiment 1
[0031] This embodiment provides a method for optimizing the water quenching process of alloy steel, which is used for processing alloy steel pieces with a diameter of 300 mm and a long axis of 42CrMo, and the quenching medium used is water.
[0032] Step 1: Determine the performance testing site and predict and obtain the organizational requirements of the testing site;
[0033] In this embodiment, the required performance part of the alloy steel part is 30 mm away from the surface along the long axis section of Ф300 mm of 42CrMo, and the microstructure of the required performance part is obtained by TTT curve prediction as 60% bainite and 40% pearlite + ferrite body.
[0034] The second step: determine the temperature to be cooled to obtain the structure by means of the isothermal transformation cooling curve of the alloy steel material;
[0035] Combined with the isothermal cooling transformation curve (TTT curve) of the alloy steel material 42CrMo, in order to obtain the e...
Embodiment 2
[0050] This embodiment relates to an optimization method of a water quenching process for an alloy steel, which is used to process a long axis of Ф150 mm made of 40Cr, and the quenching medium used is water.
[0051] Step 1: Determine the performance testing site and the organizational requirements for the testing site;
[0052] In this embodiment, the required performance part of the alloy steel part is 18 mm away from the surface along the section, and the microstructure of the required performance part is 70% bainite and 30% pearlite+ferrite predicted by the TTT curve.
[0053] The second step: determine the temperature to be cooled to obtain the structure by means of the isothermal transformation cooling curve of the alloy steel material;
[0054] Combined with the isothermal cooling transition curve (TTT) of the alloy steel material 40Cr, in order to obtain the expected structure at the position 18 mm away from the surface along the long axis of the Ф180 mm section, cool ...
Embodiment 3
[0065] This embodiment relates to a method for optimizing the water quenching process of alloy steel, which is used to process a rectangular piece with a thickness of 350 mm and the material is H13, and the quenching medium is water. If the water cooling time of this high hardenability steel is too long, the core can obtain a full bainite structure, and its residual stress state is surface tensile stress, and the core is compressive stress, and the risk of quenching cracks is relatively high.
[0066] The first step: According to the performance requirements of the alloy steel parts, predict the structure and composition to obtain the required performance;
[0067] H13 belongs to the alloy steel with high hardenability, and the performance part is required to be 50mm away from the surface along the section after quenching. The structure obtained by TTT curve prediction is 30% martensite and 70% bainite.
[0068] The second step: determine the temperature to be cooled to obtain...
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Abstract
The invention provides an optimization method of an alloy steel water quenching process. The method comprises the following steps of firstly predicting and obtaining a structure with a required performance; determining the temperature to be cooled of the structure by virtue of an isothermal transformation cooling curve of an alloy steel part material; dividing the alloy steel part into a fast cooling region and a slow cooling region along the section from surface to center, wherein the fast cooling region is a part from the surface of the alloy steel part to the required performance part or deeper, the slow cooling region is a part of the required performance part or the deeper part to a central; determining water cooling time for reducing to a preset temperature of the fast cooling regionby means of numerical simulation, optimizing water cooling time by combining the temperature returning temperature and surface stress state of the required performance part; and finally, giving out the alloy steel water quenching process. According to the method, the purpose that low / high hardenability workpiece with limited material hardenability and large size can obtain high quenching coolingperformance or the purpose of avoiding generation of quenching cracks in quenching and cooling process are met.
Description
technical field [0001] The invention relates to the field of steel heat treatment, in particular to an optimization method for a water quenching process of alloy steel. Background technique [0002] Quenching and tempering is a traditional process, which heats alloy steel parts to the austenite zone, then quenches and cools to room temperature to obtain martensite or bainite structure, and then tempers at a suitable temperature to obtain tempered Martensite or tempered bainite structure. For alloy steel quenching, oil is generally used as the quenching medium to avoid cracking. The problem is that the mechanical properties of oil quenching are much lower than that of water quenching. At the same time, oil quenching has the risk of oil smokepollution and fire. Therefore, water quenching of alloy steel parts is the future development direction, and the premise of promoting the water quenching process is to solve the problem of water quenching cracking. [0003] After search...
Claims
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Application Information
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