Method for improving toughness of high-carbon equivalent steel plate welding heat affected zone through rare earth

Abstract

The invention relates to a method for improving toughness of a high-carbon equivalent steel plate welding heat affected zone through rare earth, and belongs to the technical field of high-strength steel plates for welding. The method sequentially comprises the converter smelting step, LF refining step, RH refining step, continuous casting step, hot rolling step and thermal treatment step. According to the method, a certain amount of rare earth Ce alloy is added into molten steel during the RH refining process, inclusions in molten steel are modified into rare earth inclusions through rare earth, tiny new rare earth inclusions are generated in molten steel, and dispersed distribution of the rare earth inclusions is controlled; the tiny dispersed distribution rare earth Ce inclusions and original inclusions modified by rare earth newly generated in molten steel inhibit original austenite grains in the heat affected zone from growing during the welding process; and bainite transformationof the welding heat affected zone is delayed through addition of rare earth, formation of bainite is inhibited, and toughness of the high-carbon equivalent steel plate welding heat affected zone is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of high-strength steel plates for welding, and in particular relates to a method for improving the toughness of welding heat-affected zones of high-carbon equivalent steel plates by using rare earth. Background technique [0002] The large-scale and high-rise development of steel for construction machinery and steel for building components requires steel plates to have higher strength and good welding performance. However, as the strength of the steel plate increases, its weldability decreases significantly, and the sensitivity to weld cracks increases. Especially for thick plates with high carbon equivalent, with the increase of welding heat energy, the grain size of prior austenite in the welding heat-affected zone increases significantly, forming a coarse-grained heat-affected zone, and the post-weld heat-affected zone is easy to form upper bainite structure, significantly reducing the toughness of the w...

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Problems solved by technology

However, Ti- and Ca-containing oxide inclusions are easy to aggregate and grow in molten steel, and the particle size is mostly several microns or even larger. The above-mentioned technology does not describe its size control

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