Thick steel plate with great large line energy and low temperature toughness and its production process

Abstract

A thick steel plate with great large line energy and low temperature toughness disclosed in the invention comprises: 0.02-0.06 wt% C, 0.05-0.15 wt% Si, 1.00-1.80 wt% Mn, 0.01 wt% or less P, 0.005 wt% or less S, 0.02-0.04wt% Al, 0.002-0.005 wt% N, 0.005-0.015 wt% Ti, 0.05-0.30 wt% Cr, 0.001-0.0025 wt% B, the rest is Fe and inevitable impurities, wherein, the ratio of Ti to N is not more than 3.42.The production process of the thick steel plate comprises the following steps: smelting in a converter or an electric furnace, secondary refining in a vacuum furnace, casting billets or steel ingots,reheating the billets or steel ingots, carrying out a thermo mechanical controlling process (TMCP) and fast cooling process, so as to form the thick steel plate. According to the invention, by addingCr and B to the Ti microalloy steel, the low cost production of the thick steel plate with great large line energy and low temperature toughness is realized.

Description

technical field [0001] The invention relates to a low-alloy high-strength steel and a production process thereof, in particular to a thick steel plate with excellent high-energy-input welding low-temperature toughness and a production process thereof. Background technique [0002] At present, the global steel production capacity has excess capacity, and the problem of excess steel production capacity in China is particularly serious. In contrast, many high-end products still need to be imported in large quantities, and the homogeneity of products among various steel companies is becoming more and more serious, which will inevitably cause vicious competition and lower steel prices. In addition, the economic crisis that broke out in 2008 made The operation of iron and steel companies is facing enormous pressure. Up to now, many domestic iron and steel companies are still operating at a loss. On the other hand, mining companies led by Rio Tinto, BHP Billiton and Vale have a hi...

AI Technical Summary

Problems solved by technology

The purpose of adding Cr in Chinese patent CN200580012110.9 is to improve the corrosion resistance of steel, and the purpose of adding Cr in Chinese patent CN200410017255.5 is to improve the strength and toughness of steel, and it is believed that the addition of Cr is unfavorable to weldability; In the above two patents, other precious metals such as Nb, V, Mo, etc. are added to varying degrees, and these precious metals greatly increase the production cost; in terms of welding line energy, the welding line energy of Chinese patent CN200410017255.5 is relatively low, at 50 Between -150kJ / cm, and the peak temperature of welding heat simulation is low (usually at 1350°C), the welding heat simulation t 8 / 5 The cooling time is relatively short, less than 200s

Although the Chinese patent CN200580012110.9 can reach the welding input energy of 200-1000kJ / cm, but from the perspective of alloy design, too many alloying elements are added, such as the addition of precious metal Ni at least 0.8%, in addition to different levels of addition Precious metals Nb, V, Mo, etc., and the patent uses an oxide metallurgy process, the key technology of which lies in the steelmaking process, which also greatly increases the production cost

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