Production method for low-yield-ratio high-strength medium-thickness steel plate

A production method and technology of low yield ratio, applied in the field of production of high-strength medium-thick steel plates with low yield ratio, can solve the problems of less application of low-carbon steel, achieve cost saving, short tempering time, and lower yield ratio Effect

Inactive Publication Date: 2017-12-08
HUNAN VALIN XIANGTAN IRON & STEEL CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Reducing the yield ratio of the material requires the introduction of multi-phase structure. The more common method is to obtain a certain amount of ferrite soft phase structure through off-line two-phase zone quenching treatment. This technology is more effective in high Ni steel and high Mn steel. Common, but rarely used in the production of low carbon steel

Method used

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  • Production method for low-yield-ratio high-strength medium-thickness steel plate
  • Production method for low-yield-ratio high-strength medium-thickness steel plate
  • Production method for low-yield-ratio high-strength medium-thickness steel plate

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Embodiment 1

[0020] Embodiment one: the rolling of 25mm thick steel plate

[0021] The smelting composition of low alloy plate steel is C= 0.07, Si=0.3, Mn=1.56, Cr= 0.33, Nb= 0.04, Ti= 0.016, Mo= 0.15, B= 0.0005, P= 0.011, S= 0.002, The balance is Fe and unavoidable impurities, carbon equivalent CEQ = 0.43, cold crack sensitivity index Pcm = 0.19. After smelting, it is made into a continuous casting slab with a thickness of 260mm. Process steps include:

[0022] (1) Rolling process: After the continuous casting slab is heated by the heating furnace, the tapping temperature is 1180 o C, the thickness of the intermediate billet after 7 passes of rough rolling is 80mm, the reduction rate of the last three passes of rough rolling is above 20%, and the starting temperature of finish rolling is 935 o C, open and cold temperature is 800 o C, after online quenching, the red temperature is 440 o C with a cooling rate of 35 o C / s, rolled into a steel plate with a thickness of 25mm.

[0023] ...

Embodiment 2

[0027] Embodiment two: the rolling of 40mm thick steel plate

[0028]The smelting composition of low alloy plate steel is C 0.08, Si 0.28, Mn 1.61, Cr 0.31, Nb 0.045, Ti0.018, Mo 0.17, B 0.0008, P 0.013, S 0.002, the balance is Fe and unavoidable acrobatics Elements, carbon equivalent CEQ0.43, cold crack sensitivity index Pcm 0.19. After smelting, it is made into a continuous casting slab with a thickness of 260mm. Process steps include:

[0029] (1) Rolling process: After the continuous casting slab is heated by the heating furnace, the tapping temperature is 1190 o C, the thickness of the intermediate billet after 7 passes of rough rolling is 130mm, the reduction ratio of the last three passes of rough rolling is above 20%, and the starting temperature of finish rolling is 918 o C, open cold temperature is 785 o C, after online quenching, the red temperature is 320 o C with a cooling rate of 30 o C / s, rolled into a steel plate with a thickness of 40mm.

[0030] (2) He...

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Abstract

The invention discloses a production method of a low-yield ratio high-strength medium-thick steel plate. The chemical composition mass percentage of the steel is C=0.06-0.09, Si=0.2-0.4, Mn=1.3-1.8, Al=0.02-0.05, Cr=0.30~0.40, Nb≤0.05, Ti=0.015~0.025, Mo≤0.30, B≤0.0010, P<0.02, S<0.005, CEQ<0.45, Pcm<0.22, the process steps include rolling and heat treatment. The method of the present invention is used for rolling low-yield ratio high-strength medium-thick steel plates, especially high-strength steel medium-thick plates with a yield strength of 550 MPa for construction machinery, and finally obtains tempered strips through quenching and tempering process or TMCP+tempering process. The plate with bainite structure has a yield strength of more than 550MPa, a tensile strength of more than 680MPa, a yield ratio of less than 0.9, an elongation after fracture of more than 17%, and a full-thickness V-notch Charpy impact energy of more than 140J at -20°C. . And excellent performance after welding.

Description

technical field [0001] The invention belongs to the technical field of steelmaking, and relates to a method for producing medium-thick steel plates with low yield ratio and high strength. Background technique [0002] In the field of high-end equipment manufacturing, the lightweight of complete sets of construction machinery equipment is the key breakthrough direction. The application of high-strength steel to key operating components such as booms and underframes and main load-bearing components determines the performance of large-scale construction machinery and is also the key to lightweight. Under the extreme working conditions of ultra-long and heavy loads, there are also high requirements for steel plate shape, product mechanical properties, cold bending properties, welding, fatigue properties, etc. With the development of large-scale equipment manufacturing, in addition to improving the weight reduction of materials, it is also necessary for materials to have a bette...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/38C22C38/26C22C38/28C22C38/22C22C38/32B21C37/02C21D8/02
CPCC22C38/02B21C37/02C21D8/0205C21D8/0221C21D8/0247C21D2211/002C21D2211/008C22C38/04C22C38/06C22C38/22C22C38/26C22C38/28C22C38/32C22C38/38
Inventor 周文浩张青学李玉路郑健孙小平刘丹罗登
Owner HUNAN VALIN XIANGTAN IRON & STEEL CO LTD
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