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A preparation method of niobium-containing nano-bainite steel with good thermal stability

A technology for thermal stability of bainitic steel, applied in the field of iron and steel materials, can solve the problems of unreported thermal stability of nano-bainitic steel, difficulty in precise control, complicated production process, etc., to compensate for the reduction of dislocation density and easy The effect of simple operation and process

Active Publication Date: 2022-04-12
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the production process is relatively complex and difficult to precisely control
And the research on the thermal stability of the prepared nano-bainitic steel has not been reported yet.

Method used

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  • A preparation method of niobium-containing nano-bainite steel with good thermal stability
  • A preparation method of niobium-containing nano-bainite steel with good thermal stability
  • A preparation method of niobium-containing nano-bainite steel with good thermal stability

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] The embodiment of the present invention provides a preparation method of niobium-containing nano-bainite steel with good thermal stability. The chemical composition and content of the bainite steel are: C 0.28%; Si 1.50%; Mn 1.5%; Cr 1.2% %; Al 1.97%; Mo0.80%; Ni 0.62%; Nb 0.018%; the rest is Fe and unavoidable impurities.

[0023] Its heat treatment method specifically comprises the following steps:

[0024] The nano-bainitic steel billet was homogenized at 1200°C for 24 hours under vacuum to reduce the segregation of alloying elements. After cooling to room temperature, take Cylindrical samples. The start temperature of martensitic transformation of the nano-bainite steel was determined to be 330°C with a Gleeble 3500 thermal simulator.

[0025] The nano-bainite steel was austenitized at 980°C for 0.5h; then cooled to 330°C at a rate of 20°C / s and held for 1h. Finally air cool to room temperature.

[0026] figure 1 and figure 2 The microstructures of niobium-...

Embodiment 2

[0030] The embodiment of the present invention provides a method for preparing niobium-containing nano-bainite steel with good thermal stability. The chemical composition and content of the bainite steel are: C 0.29%; Si 1.40%; Mn 1.50%; Cr 1.30 %; Al 1.6%; Mo0.89%; Ni 0.61%; Nb 0.019%; the rest is Fe and unavoidable impurities.

[0031] Its heat treatment method specifically comprises the following steps:

[0032] The nano-bainitic steel blank was homogenized at 1200°C for 24 hours under vacuum to reduce the segregation of alloying elements. After cooling to room temperature, take Cylindrical samples. Using Gleeble3500 thermal simulation testing machine, it was measured that the martensitic transformation initiation temperature of the nano-bainite steel was 332°C.

[0033] The nano-bainitic steel was austenitized at 1000°C for 0.5h; then cooled to 335°C at a rate of 20°C / s and kept at a temperature of 1h. Finally air cool to room temperature.

[0034] Figure 4 The micr...

Embodiment 3

[0038] The embodiment of the present invention provides a preparation method of niobium-containing nano-bainite steel with good thermal stability. The chemical composition and content of the nano-bainite steel are: C 0.32%; Si 1.40%; Mn 1.51%; Cr 1.18%; Al 1.16%; Mo 0.49%; B 0.003%; Ni 0.61%; Nb 0.019%; the rest is Fe and unavoidable impurities.

[0039] Its heat treatment method specifically comprises the following steps:

[0040] The nano-bainitic steel billet was homogenized at 1200°C for 24 hours under vacuum to reduce the segregation of alloying elements. After cooling to room temperature, take Cylindrical samples. Using a Gleeble 3500 thermal simulation testing machine, it was determined that the martensitic transformation initiation temperature of the nano-bainite steel was 328°C.

[0041] The nano-bainitic steel was austenitized at 1000°C for 0.5h; then rapidly cooled to 323°C at a rate of 30°C / s, and kept for 5s; then kept at 340°C for 1h; finally air-cooled to ro...

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Abstract

The invention discloses a method for preparing niobium-containing nano-bainite steel with good thermal stability, which belongs to the field of iron and steel materials. Keep the niobium-containing nano-bainite steel blank at 50-100°C above the complete austenitization temperature (Ac3) for 0.5-1.0h; then directly cool it to the martensite initiation temperature at a rate of 20-50°C / s (Ms) above 5-15°C for isothermal bainite transformation, the isothermal time is 1.0-2.0h; or directly cooled to 5-8°C below the martensite initiation temperature (Ms) to form a small amount of martensite, and then heat up The two-step isothermal bainite transformation is carried out at 5-15°C above the martensite transformation temperature (Ms), and the isothermal time is 0.5-1.0h. Finally air cool to room temperature. The chemical composition of the nano-bainite steel is: C 0.25-0.30%; Si 1.2-1.5%; Mn 1.0-1.7%; Cr 1.2-1.5%; Al 1.5-2.0%; Mo 0.8-1.0%; Ni 0.6% ~1.0%; Nb 0.015~0.020%, the rest is iron and unavoidable impurities. The invention relates to a process that does not require complicated rolling deformation, and has short phase transformation completion time, and can ensure the mechanical stability of the nano-bainite steel at high temperature while refining the microstructure of the nano-bainite.

Description

technical field [0001] The invention belongs to the field of iron and steel materials, and in particular relates to a preparation method of niobium-containing nano-bainite steel with good thermal stability. Background technique [0002] Nano-bainite steel, also known as low-temperature bainite steel or ultra-fine bainite steel, mostly uses high-carbon and high-silicon alloy components, and is formed above the martensitic transformation start temperature (Ms) (200-300°C). Long-time isothermal bainite transformation to obtain nanoscale bainitic ferrite laths and film-like retained austenite. The high dislocation density in the hard phase of bainitic ferrite lath can provide higher strength, and the soft phase of retained austenite (film-like retained austenite and massive retained austenite) can ensure that the material has considerable plasticity and toughness. However, the transformation time of nano-bainite in high-carbon and high-silicon bainite steel prolongs with the d...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C33/04C22C38/02C22C38/04C22C38/06C22C38/44C22C38/48C22C38/58C21D1/20C21D6/00
CPCC22C33/04C22C38/02C22C38/04C22C38/06C22C38/58C22C38/48C22C38/44C21D6/004C21D6/005C21D6/008C21D1/20
Inventor 武会宾于新攀顾洋张游游袁睿宁博汤启波刘金旭
Owner UNIV OF SCI & TECH BEIJING
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