Low-alloy high-strength steel welding process

Abstract

The invention discloses a technological method for welding low-alloy high-strength steel, which comprises the following steps: a divided edge is formed, a welding area is polished and cleaned, and the strength of welding material is equivalent to that of steel to be welded; Ar+CO2 mixed gas protective welding is adopted, preheating is performed before welding, and the welding speed is 250-300mm / min; a 800MPa solid welding wire is adopted to perform multilayer multirun welding; the interlayer temperature is kept at 150 DEG C plus or minus 20 DEG C during the welding process, a preheating spray gun is used from time to time for temperature compensation, the welding line energy is 16-18KJ / cm, low temperature aging is performed to the whole after welding, and the temperature is 300-400 DEG C. The welding technological method prevents welding cracks from being generated, eliminates residual stress generated during welding large-sized structural members, and serves the purpose that the tensile strength of weld joins equals the tensile strength of parent metal.

Description

technical field [0001] The invention relates to a low-alloy high-strength steel welding process method. Background technique [0002] As one of the main equipment of the fully mechanized mining face, the hydraulic support, with the further improvement of the frame structure and the more advanced design method, the parameters began to develop in the direction of high working resistance and large center distance. With the increase of the working resistance of the support and the increase of the number of durability tests, if the traditional 16Mn and 15MnVN are used to ensure the support strength of the support, only increasing the thickness of the plate will inevitably make the overall weight of the support overweight, which will seriously affect the mine lifting and underground. Transportation and work surface handling all bring great inconvenience. Therefore, in the case of ensuring that the support strength and the total weight of the bracket do not exceed the standard, th...

AI Technical Summary

Problems solved by technology

Because of this, more and more high-strength steel materials are being used as support structure materials. The main structural parts are gradually replaced by high-strength steel plates of different grades with σs of 450-900 MPa 16Mn (σs is 320-350 MPa). The research on the welding performance of steel started relatively late, and the coal machinery plants are more based on experience, basically in the situation of exploring and producing at the same time, due to improper selection of welding process, welding cracks are prone to occur

Moreover, a large number of electron diffraction analyzes of the weld metal structure of low-alloy high-strength steel with a tensile strength of 500-1000MPa show that there is an M-A structure in the weld metal of high-strength steel. When the alloy element content is low, the M-A structure is granular; when the alloy element When the content is high, it is in the shape of lath. Whether the M-A structure in the weld metal is distributed in granular or lath form, when they exist continuously, the impact toughness of the weld metal will be significantly reduced.