Welding process for ultrahigh-strength steel plate with yield strength larger than or equal to 1250 MPa

Abstract

The invention relates to a welding process for an ultrahigh-strength steel plate with the yield strength larger than or equal to 1250 MPa, and belongs to the technical field of ultrahigh-strength steel welding. The welding process comprises the following steps: 1, a small iron research test is carried out, and the pre-welding preheating temperature of the ultrahigh-strength steel is determined; 2,the preheating temperature of welding test plates is obtained according to the small iron research test, and the welding test plates are overall preheated; 3, the welding test plates are in butt joint, argon-rich gas is selected as protective gas, and austenitic stainless steel MIG welding wires are adopted for forward welding and reverse welding, wherein the temperature between welding bead layers and between welding beads is controlled to be smaller than or equal to 150 DEG C, and the welding heat input is controlled to be 8-12 KJ / cm; and 4, post-welding inspection and flaw detection are carried out. Welding is conducted in a butt-joint mode, the preheating temperature of the welding test plates is obtained by selecting the austenitic stainless steel MIG welding wires and carrying out the small iron research test, reasonable welding technological parameters are designed, the welding process is strictly controlled, weldability is high, welded joints have good ductility, toughness andcrack resistance after welding, welding joint deformation is small, and welding defects are avoided.

Description

technical field [0001] The invention relates to a welding process of an ultra-high-strength steel plate with a yield strength≧1250MPa, belonging to the technical field of ultra-high-strength steel welding. Background technique [0002] Low-alloy high-strength steel plates are mainly used in mechanical equipment manufacturing. In order to improve the overall level and market competitiveness of China's machinery manufacturing industry and meet the development needs of large-scale and lightweight construction machinery, a large number of high-quality high-strength ultra-thick steel plates are urgently needed. At present, steel mills have successfully developed ultra-high-strength steel plates with a strength exceeding 1250MPa. The steel plates have excellent performance, but there are the following welding problems: First, the weldability is poor, and welding cold cracks are prone to occur after welding. , the corresponding preheating temperature should not be too high, otherwi...

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Problems solved by technology

At present, steel mills have successfully developed ultra-high-strength steel plates with a strength exceeding 1250MPa. The steel plates have excellent performance, but there are the following welding problems: First, the weldability is poor, and welding cold cracks are prone to occur after welding. , the corresponding preheating temperature should not be too high, otherwise the strength of the steel plate will be severely reduced, but the sensitivity of ultra-high strength steel to cold cracks requires the preheating temperature to be as high as possible. This contradiction has brought great challenges to welding workers

Secondly, the control of welding heat input is very strict. If the heat input is too high, it will cause serious softening of the heat-affected zone, which will seriously reduce the strength of the joint; Case

Finally, the wall thickness of the general ultra-high-strength steel plate is relatively thin, the deformation of the test plate after welding is serious, and the phenomenon of warping and bending of the welded test plate occurs from time to time

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