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Austenite low-temperature steel and preparation method thereof

A low-temperature steel and austenitic technology, which is applied in the field of low-temperature steel and its preparation, can solve the problems of complex preparation process and difficult implementation, and achieve the effects of cost reduction, excellent low-temperature impact toughness, and reduced use of Ni

Inactive Publication Date: 2019-03-26
NANJING IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The prepared high-manganese steel has high strength and high elongation, but fails to provide a technical solution for achieving excellent low-temperature toughness, and the preparation process includes coiling, annealing, water quenching, etc. The preparation process is complicated and difficult to implement

Method used

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  • Austenite low-temperature steel and preparation method thereof
  • Austenite low-temperature steel and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] An austenitic low-temperature steel, its chemical composition and mass fraction are: 17.2% Mn, 1% Ni, 3.9% Cr, 0.57% C, 0.05% Nb, 0.21% Si, 0.1% Al, 0.05% N, the balance It is Fe and S and P impurity elements below 0.05%, 50C+Mn+1.8Ni+1.3Cr=52.57%.

[0038] A steel billet with a thickness of 150mm is heated to 1120°C and held for 180min; after heating, it is rolled, the final rolling temperature is 980°C, the deformation of each pass is 20%, the total deformation is 85%, and the thickness of the steel plate is 22.5mm; immediately after rolling, it is water-cooled to room temperature , The cooling rate is 23°C / s in the range of 400-850°C.

[0039] figure 2 Shown is the optical microstructure of low temperature steel, the structure is austenitic. The volume fraction of austenite is 99.4%, the average grain diameter is 63μm, almost no carbide, and the impact energy of Charpy impact test at -196℃ is 164J.

Embodiment 2

[0041] 19.8% Mn, 1.3% Ni, 4.9% Cr, 0.43% C, 0.1% Nb, 0.1% Si, 0.02% Al, 0.12% N, and the balance Fe and S, P impurity elements below 0.05%; 50C+Mn +1.8Ni+1.3Cr=50.01%

[0042] A steel billet with a thickness of 220mm is heated to 1050°C and held for 300min; after heating, it is rolled, the final rolling temperature is 960°C, the deformation of each pass is 15%, the total deformation is 75%, and the thickness of the steel plate is 55mm; immediately after rolling, it is water-cooled to room temperature, 400 The cooling rate in the range of ~850°C is 60°C / s.

[0043] The volume fraction of austenite is 99.6%, the average grain diameter is 75μm; there is almost no carbide, and the impact energy of Charpy impact test at -196℃ is 203J.

[0044] In this example, the contents of Mn, Ni, and Cr are close to the upper limit of the range, and the content of C is relatively low, but the total alloy content is 50C+Mn+1.8Ni+1.3Cr=50%, and a stable austenite structure can also be obtained. ...

Embodiment 3

[0046] 20% Mn, 1.25% Ni, 5% Cr, 0.7% C, 0.02% Nb, 0.6% Si, 0.3% Al, 0.015% N, and the balance of Fe and S, P impurity elements below 0.05%; 50C+Mn +1.8Ni+1.3Cr=63.75%.

[0047] A billet with a thickness of 80mm is heated to 1180°C and held for 65min; after heating, it is rolled, the final rolling temperature is 1020°C, the deformation of each pass is 22%, the total deformation is 90%, and the thickness of the steel plate is 8mm; immediately after rolling, it is water-cooled to room temperature, 400 The cooling rate in the range of ~850°C is 10°C / s.

[0048] The volume fraction of austenite is 98.5%, the average grain diameter is 71μm; there are very few carbides at the grain boundary, and the impact energy of Charpy impact test at -196℃ is 94J.

[0049] In this embodiment, the contents of Mn, Ni, and Cr are close to the upper limit of the range, and the content of C is also close to the upper limit of the range. Although the higher content of C and Cr increases the carbide i...

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Abstract

The invention discloses austenite low-temperature steel and a preparation method thereof. The austenite low-temperature steel is prepared from the chemical components in mass fraction: 14 to 20 percent of Mn, 0.3 to 1.3 percent of Ni, 2 to 5 percent of Cr, C meeting the conditions that 50C+Mn+1.8Ni+1.3Cr is larger than or equal to 50 percent and C is less than or equal to 0.7 percent, 0.02 to 0.1percent of Nb, larger than 0 and less than or equal to 0.6 percent of Si, larger than 0 and less than or equal to 0.3 percent of Al, larger than 0 and less than or equal to 0.12 percent of N, and thebalance Fe and inevitable impurity elements. The volume fraction of an austenite structure of the low-temperature steel is larger than or equal to 97 percent, the average grain diameter is less than or equal to 80mum, and the charpy impact test impact energy at minus 196 DEG C is larger than or equal to 80J. The preparation method comprises the steps of heating, deforming and cooling a steel billet with the same chemical component of the austenite low-temperature steel, adopting a process combining high-temperature thermomechanical treatment and water toughening treatment, and preparing to obtain the high-manganese low-nickel micro-niobium austenite low-temperature steel with excellent impact toughness. The preparation method is simple.

Description

technical field [0001] The invention relates to a low-temperature steel and a preparation method thereof, in particular to an austenitic low-temperature steel and a preparation method thereof. Background technique [0002] The storage and transportation of substances such as liquefied natural gas (boiling point -162°C), liquid oxygen (boiling point -183°C) and liquid nitrogen (boiling point -196°C) require structural materials with high impact toughness at ultra-low temperatures. As commonly used low-temperature steels, materials such as 9% Ni steel and Cr-Ni austenitic stainless steel need to add a large amount of expensive Ni element, so the cost is high. The main microstructure of 9% Ni steel is martensite. Although the strength is high, controlled rolling and cooling and multiple heat treatments are required in the manufacturing process, which is difficult to manufacture. In addition, magnetic deflection is prone to occur during welding. High difficulty. In contrast, t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/58C22C38/48C22C38/02C22C38/06C21D8/00
CPCC21D8/005C22C38/02C22C38/06C22C38/48C22C38/58C21D2211/001C22C38/001C21D1/02C21D6/004C21D6/005C21D1/60C21D8/0226C21D8/0263C21D8/0205
Inventor 孙超毛泽宁李东晖李强赵柏杰楚觉非
Owner NANJING IRON & STEEL CO LTD
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