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Low-alloy super-strength multiphase steel and heat treatment method thereof

A heat treatment method and ultra-high strength technology, applied in the field of alloy steel and its heat treatment, to achieve the effect of excellent comprehensive mechanical properties

Active Publication Date: 2008-07-23
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The Chinese patent application number is 2007100458861, titled "Heat Treatment Method for Improving the Mechanical Properties of Quenched Steel Parts Using Carbon Distribution and Tempering". The patent obtained is a three-phase structure of martensite, retained austenite and tempered carbides. The principle of precipitation phase strengthening is used, and a new type of nano-bainite structure with excellent strength and toughness is not introduced.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] The composition of low-alloy medium carbon steel is 0.49% of C content, 1.20% of Mn content, 1.18% of Si content, 1.00% of Ni content, 0.21% of Nb content, 0.003% of S content, and 0.007% of P content. The rest is Fe (all are mass fractions). The workpiece is heated to 820°C for austenitization, and then quenched into a Sn-Bi bath at 185°C. After isothermal for a few seconds, it is immediately quenched to 300°C (salt bath) for 600s. At this time, the carbon is distributed from martensite to the horse. Among the austenite between the austenite, the retained austenite is enriched with carbon, and then the oil is quenched to 185°C for 24 hours, so that most of the carbon-rich retained austenite is transformed into nano-bainite, and then quenched with water to room temperature . After testing, the yield strength of steel parts Rp 0.2 It is 1270MPa, the tensile strength Rm is 1805MPa, and the total elongation is 14.6%. Rockwell hardness (HRC) is 53.3.

Embodiment 2

[0023] The low-alloy medium carbon steel has a C content of 0.49%, a Mn content of 1.2%, a Si content of 1.18%, a Ni content of 1%, a Nb content of 0.21%, an S content of 0.003%, and a P content of 0.007%. The rest is Fe (all are mass fractions). The workpiece is heated to 820℃ for austenitization, then quenched into a Sn-Bi bath at 190℃. After a few seconds, it is immediately quenched to 345℃ (salt bath) for 60s, and then oil quenched to 190℃ for 48h. Finally, water Quench to room temperature. After testing, the yield strength of steel parts Rp 0.2 It is 1561MPa, the tensile strength Rm is 1969MPa, and the total elongation is 13.3%. Rockwell hardness (HRC) is 54.7.

Embodiment 3

[0025] The low-alloy medium carbon steel has a C content of 0.49%, a Mn content of 1.2%, a Si content of 1.18%, a Ni content of 1%, a Nb content of 0.21%, an S content of 0.003%, and a P content of 0.007%. The rest is Fe (all are mass fractions). The workpiece is heated to 820°C for austenitization, and then quenched into a Sn-Bi bath at 150°C. After a few seconds, it is immediately quenched to 400°C for 15s, then oil quenched to 195°C for 24 hours, and then quenched to room temperature with water. After testing, the yield strength of steel parts Rp 0.2 It is 1339MPa, the tensile strength Rm is 2017MPa, and the total elongation is 11.7%. Rockwell hardness (HRC) is 55.3.

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Abstract

The invention discloses a low-alloy superhigh-intensity diphase steel and the heat treatment method, which is characterized in that: the components of the diphase steel (wt %) are C of 0.3 to 0.7, Si of 0.01 to 3.0, Al of 0.0 to 2.0, Nb of 0.0 to 0.25, V of 0.0 to 0.3, Mo of 0.0 to 2.0, Ni of 0.0 to 4.0, Mn of 0.05 to 3.0, Cr of 0.00 to 3.0, Co of 0.00 to 2.0, W of 0.0 to 2.0, S less than 0.04, P less than 0.04 and Fe of balance; the heat treatment method is that: a workpiece is first heated to 800 to 1000 degree centigrade to process the austenite treatment, and then the workpiece is quickly quenched into a liquid quenching medium of 50 to 250 degree centigrade, and then the workpiece is partitioned in a liquid quenching medium of 250 to 450 degree centigrade, and then the workpiece is quickly quenched into a liquid quenching medium of 100 to 250 degree centigrade for holding, finally the workpiece is quenched into water, and then the workpiece has a three-phase organization with martensite, nanometer ferrito martensite and remaining austenite with rich carbon. The low-alloy superhigh-intensity diphase steel and the heat treatment method has an advantage of increasing the intensity and plasticity of workpieces.

Description

Technical field [0001] The invention relates to an alloy steel in the technical field of materials and a heat treatment method thereof, in particular to a low-alloy ultra-high-strength duplex steel and a heat treatment method thereof. Background technique [0002] Heat treatment has always been one of the important processes in the production of steel materials. Compared with other processing technologies, heat treatment generally does not change the shape and overall chemical composition of the workpiece, but by changing the internal microstructure of the workpiece, or changing the surface of the workpiece. The chemical composition imparts or improves the comprehensive performance of steel materials. Retained austenite is an important factor affecting the plasticity of steel materials. When there is plastic deformation, the transformation of retained austenite into martensite is an important reason for the good plasticity of steel materials. Although the traditional martensitic ...

Claims

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Application Information

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IPC IPC(8): C22C38/52C21D6/00C21D1/19
Inventor 金学军李洪岩陈科
Owner SHANGHAI JIAO TONG UNIV
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