Medium-carbon silicon-manganese low alloy steel heat treatment process based on carbon partitioning and two-step isothermal quenching

A low-alloy steel, medium-carbon silicon-manganese technology, which is applied in the field of heat treatment technology of medium-carbon silicon-manganese low-alloy steel to achieve the effects of good comprehensive mechanical properties, improved toughness, and refined structure

Active Publication Date: 2021-08-27
SICHUAN UNIV +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] In order to achieve the above object, the present invention provides a heat treatment process for medium-carbon silicon-manganese low-alloy steel based on carbon partitioning and two-step austempering, which eliminates massive untransformed austenite through two-step austempering, thereby regulating the product content. Phase morphology, refined structure, improved performance, carbon partition is beneficial to ensure the volume fraction of retained austenite in the final structure, and a fine bainite / martensite / retained austenite composite structure can be obtained after heat treatment , has good comprehensive mechanical properties, especially the toughness has been significantly improved, and solves the problems of technical difficulties, prejudices and misunderstandings in improving the mechanical properties of medium-carbon silicon-manganese low-alloy steel in the prior art

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  • Medium-carbon silicon-manganese low alloy steel heat treatment process based on carbon partitioning and two-step isothermal quenching
  • Medium-carbon silicon-manganese low alloy steel heat treatment process based on carbon partitioning and two-step isothermal quenching
  • Medium-carbon silicon-manganese low alloy steel heat treatment process based on carbon partitioning and two-step isothermal quenching

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Experimental program
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Effect test

Embodiment 1

[0046] The chemical composition of medium-carbon silicon-manganese low-alloy steel is 0.28%C, 1.56%Si, 1.91%Mn, 0.83%Cr, 0.20%Ni, 0.07%V, 0.013%P, 0.004%S, and the rest is Fe, Using the German Bahr DIL805 A / D dilatometer to measure the Ms point of the carbon-silicon-manganese low-alloy steel in this composition is 316°C, the Ac3 is 852°C, and the M f It is 157°C.

[0047] (1) Forging a medium-carbon silicon-manganese low-alloy steel cast slab with a width of 100mm and a thickness of 55mm at a temperature of 1100°C into a blank with a thickness of 25mm;

[0048] (2) Obtain samples of width 10mm x thickness 10mm x length 55mm, width 6mm x thickness 4mm x length 85mm on a 25mm thick blank;

[0049] (3) Heat the sample to 900°C, keep it warm for 25 minutes, and perform austenitization treatment to obtain a fully austenitized sample;

[0050] (4) Carry out one-step isothermal quenching to the fully austenitized sample, the quenching temperature is 245°C, the quenching rate is 60°...

Embodiment 2

[0055] The chemical composition of medium-carbon silicon-manganese low-alloy steel is 0.32%C, 1.45%Si, 1.80%Mn, 1.02%Cr, 0.18%Mo, 0.10%Ni, 0.05%V, 0.06%Nb, 0.015%P, 0.005% S, the rest is Fe, the measured Ms point of steel with this composition is 300°C, Ac3 is 848°C, M f It is 141°C.

[0056] Except that the quenching temperature of one-step austempering in (4) is 261°C, the volume fraction of martensite in the obtained phase microstructure is a medium-carbon silicon-manganese low-alloy steel with a volume fraction of 35%, and the isothermal time is 60min;

[0057] (5) The quenching temperature of the second step of isothermal quenching is 200°C, and the isothermal time is 60min;

[0058] All the other are identical with embodiment 1.

[0059] The medium-carbon silicon-manganese low-alloy steel processed by the heat treatment process described in this embodiment: the tensile strength is 1582MPa, the elongation is 20.2%, the impact energy of the U-shaped notch sample reaches ...

Embodiment 3

[0061] The chemical composition of medium-carbon silicon-manganese low-alloy steel is 0.37%C, 1.86%Si, 1.03%Mn, 1.69%Cr, 0.01%P, 0.005%S, and the rest is Fe. The Ms point of the composition steel is measured is 308°C, Ac3 is 848°C, M f It is 145°C.

[0062] Except that the quenching temperature of one-step austempering in (4) is 265°C, the volume fraction of martensite in the obtained phase microstructure is a medium-carbon silicon-manganese low-alloy steel with a volume fraction of 38%, and the isothermal time is 45min;

[0063] (5) The quenching temperature of the second step of isothermal quenching is 230°C, and the isothermal time is 120min;

[0064] All the other are identical with embodiment 1.

[0065] The medium-carbon silicon-manganese low-alloy steel processed by the heat treatment process described in this embodiment: the tensile strength is 1605MPa, the elongation is 21.8%, the impact energy of the U-shaped notch sample reaches 102J, and the XRD is used to measur...

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Abstract

The invention discloses a medium-carbon silicon-manganese low alloy steel heat treatment process based on carbon partitioning and two-step isothermal quenching. The heat treatment process comprises the following steps that a medium-carbon silicon-manganese low alloy steel casting blank is forged into a blank; a sample is obtained from the blank; austenitizing is carried out on the sample; first-step isothermal quenching is carried out on the completely austenitized sample; then second-step isothermal quenching is immediately carried out; and medium-carbon silicon-manganese low-alloy steel with a fine bainite / martensite / retained austenite complex-phase structure is obtained. According to the medium-carbon silicon-manganese low-alloy steel heat treatment process based on carbon partitioning and two-step isothermal quenching, blocky unconverted austenite is eliminated through two-step isothermal quenching treatment, so that the phase morphology of a product is regulated and controlled, the structure is refined, and the performance is improved; and the volume fraction of retained austenite in the final structure is guaranteed through carbon partitioning, and the fine bainite / martensite / retained austenite complex-phase structure is obtained after heat treatment, so that the good comprehensive mechanical property is achieved.

Description

technical field [0001] The invention belongs to the technical field of alloy steel heat treatment, and relates to a heat treatment process for medium-carbon silicon-manganese low-alloy steel based on carbon partitioning and two-step austempering. Background technique [0002] Medium-carbon silicon-manganese low-alloy steels are widely used in the fields of automobiles, petroleum, pipelines, and rail transit. Among them, the addition of silicon can inhibit the precipitation of carbides, and the addition of manganese can reduce the transformation of bainite and martensite. The role of temperature. With the development of industry, the use of alloy steel components is increasingly towards lightweight and multi-purpose, which puts forward higher requirements for the strength, toughness and plasticity of medium-carbon silicon-manganese low-alloy steel. [0003] In the traditional process, steel mainly obtains high strength and hardness through the quenching-tempering process, bu...

Claims

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Application Information

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IPC IPC(8): C21D1/20C21D6/00C22C38/02C22C38/04C22C38/34C22C38/38
CPCC21D1/20C21D6/002C21D6/005C21D6/008C22C38/02C22C38/04C22C38/34C22C38/38C21D2211/002C21D2211/008C21D2211/001Y02P10/20
Inventor 李强国张亚楠张亚宁
Owner SICHUAN UNIV
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