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

A technology of bainitic steel and thermal stability, applied in the field of iron and steel materials, can solve problems such as difficult precise control, complex production process, and unreported thermal stability of nano-bainite steel, and achieve easy operation, simple process, and compensation Effect of Dislocation Density Reduction

Active Publication Date: 2021-06-18
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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  • Preparation method of niobium-containing nano bainite steel with good thermal stability
  • Preparation method of niobium-containing nano bainite steel with good thermal stability
  • 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 with 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 preparation method of niobium-containing nano bainite steel with good thermal stability, and belongs to the field of steel and iron materials. A niobium-containing nano bainite steel blank is subjected to heat preservation for 0.5-1.0 h at the temperature 50-100 DEG C higher than the complete austenitizing temperature (Ac3); then the blank is directly cooled to the temperature 5-15 DEG C higher than the martensite phase transformation starting temperature (Ms) at the speed of 20-50 DEG C / s, isothermal bainite transformation is performed, and the isothermal time is 1.0-2.0 hours; or the blank is directly cooled to the temperature 5-8 DEG C lower than the martensite phase transformation starting temperature (Ms) to form a small amount of martensite, and then the blank is heated to the temperature 5-15 DEG C higher than the martensite phase transformation starting temperature (Ms) to be subjected to two-step isothermal bainite transformation, and the isothermal time is 0.5-1.0 h; and the blank is finally air-cooled to the room temperature. The nano bainite steel is prepared from the chemical components including 0.25%-0.30% of C, 1.2%-1.5% of Si, 1.0%-1.7% of Mn, 1.2%-1.5% of Cr, 1.5%-2.0% of Al, 0.8%-1.0% of Mo, 0.6%-1.0% of Ni, 0.015%-0.020% of Nb, and the balance Fe and inevitable impurities. According to the technology, complex rolling deformation is not needed, the phase change completion time is short, and the mechanical stability of the nano bainite steel at the high temperature can be guaranteed while the nano bainite microstructure is refined.

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 Applications(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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