Method for raising large heat input weldability of thick steel plate

Abstract

The invention discloses a method for raising large heat input weldability of a thick steel plate, comprising the following steps: 1) smelting and casting to form a steel plate: adding deoxidizers in the deoxidation process of the liquid steel according to the following types and order: Mn, Si, Al, Ti, and Ca and / or Mg, controlling the initial oxygen place in the liquid steel when Mn deoxidation is carried out in casting, adding Fe2O3 powder to let the oxygen content in the liquid steel be 0.001-0.008 wt%, wherein, the steel plate comprises 0.05-0.09 wt% of C, 0.10-0.30 wt% of Si, 1.3-1.7 wt% of Mn, 0.005-0.02 wt% of Ti, no larger than 0.015 wt% of P, no larger than 0.01 wt% of S, no larger than 0.006 wt% of N, no larger than 0.004 wt% of Ca, and the balance consisting of Fe; in the steel, the volumn density of TiN deposition with the particle size of less than 500 nm is larger than 9.0*107 PCs / mm<3>, the average particle size is less than 80 nm, and the proportion of the deposition with the particle size of less than 100 nm is larger than 75 %; 2) rolling and cooling. The large amount of nano TiN deposition with dispersive distribution formed by the invention can inhibit the growth of austenite crystals in the heat affected zone, and greatly raise the large heat input weldability of the thick steel plate.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy and iron and steel materials, in particular to a method for improving the welding performance of thick steel plates with large heat input. Background technique [0002] For shipbuilding, construction, pressure vessels, oil and gas pipelines, and offshore platforms, improving the high heat input welding performance of thick steel plates can improve welding efficiency, shorten manufacturing hours, and reduce manufacturing costs. Therefore, the toughness of the welding heat-affected zone of thick steel plates can be improved. has become an increasingly urgent requirement. [0003] After high input energy welding, the structure of the steel is destroyed, and the austenite grains grow obviously, forming a coarse-grained heat-affected zone, which reduces the toughness of the welded heat-affected zone. The structures that cause embrittlement in the coarse-grained heat-affected zone are coarse gr...

AI Technical Summary

Problems solved by technology

However, in the process of large input energy welding with welding input energy greater than 200kJ / cm, titanium oxide alone is still not enough to improve the toughness of the welding heat-affected zone

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