800MPa-grade low-welding crack sensitivity steel plate and manufacturing method thereof

Abstract

The invention provides a 800MPa-grade low-welding crack sensitivity steel plate and a manufacturing method thereof. The 800MPa-grade low-welding crack sensitivity steel plate is prepared from the following components in percentage by weight: 0.06 to 0.08 percent of C, 0.12 to 0.50 percent of Si, 1.50 to 1.85 percent of Mn, less than or equal to 0.020 percent of P, less than or equal to 0.010 percent of S, 0.20 to 0.60 percent of Cr, 0.015 to 0.060 percent of Nb, 0.010 to 0.060 percent of Alt, 0.008 to 0.035 percent of Ti, less than or equal to 0.005 percent of B, less than or equal to 0.08 percent of Mo, less than or equal to 0.15 percent of Ni, less than or equal to 0.15 percent of Cu, less than or equal to 0.21 percent of Pcm and the balance of Fe and inevitable impurities. According to the 800MPa-grade high-strength steel and the production method, precious metal Mo, Ni, Cu and V are not added in the component design, the effects of C, Mn, Cr and B elements are fully played, the structure is refined by adopting the controlled rolling and three-stage controlled cooling process and the tempering process, and the 800MPa-grade high-strength steel with the cold crack sensitivity coefficient smaller than or equal to 0.21 is obtained.

Description

technical field [0001] The invention relates to the technical field of iron and steel metallurgy, in particular to an 800MPa grade low welding crack sensitivity steel plate and a manufacturing method thereof. Background technique [0002] 800MPa high-strength steel is mainly used in construction machinery such as lifting machinery, excavator cantilever beams, hydraulic supports for mines, etc. The manufacturing method usually adopts quenching + tempering or TMCP + tempering. In order to ensure the strength of the material, it is generally necessary to add hardenable elements , such as Ni, Mo, Cu, Cr, B and other alloys, generally have higher carbon content and higher crack sensitivity. [0003] High-strength steel with low welding crack sensitivity does not crack when welded without preheating or low preheating, and is called CF (Crack Free) steel internationally. The main characteristics of this type of steel are low Pcm, low carbon equivalent, excellent welding performanc...

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Problems solved by technology

[0005] China Invention Patent Application No. 201210196864.3 discloses an 800MPa grade low welding crack sensitivity steel plate and its manufacturing method, and provides a manufacturing method of a 690MPa yield strength steel plate, The steel plate produced by this method has good toughness and weldability, and its Pcm≤0.21, but this method needs to add expensive alloys such as Mo, and the cost of the alloy is high

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