Study On The Welding Technology For Thick Steel Plate Under Low Temperatures

In recent years, with the development of economic construction and the acceleration of urbanization, the super high-rise steel structure and large span steel structure buildings appear in large numbers, thick steel plate steel in construction has also been more extensive used. The field conditions, welding position and welding environment will have an impact on the weld ability of steel, welding parameters, welding stress and deformation control of such weld. Also the impact has some uncertain factors, among this the scene environmental is an important factor in the impact of the quality of welding. The issue of welding at low temperatures (winter construction) has always been the common concern of academic and engineering.In this paper, we take the successful application of the thick steel plate welding technology under low temperature in Qingdao Center Project of China Railway as background. Based on the comparison of welding scheme,15models were established and the environment temperature were-20℃,20℃and200℃respectively, also the welds were stratified one layer, two layers, three layers, four layers and six layers., Simulation analysis of the welding temperature field and residual stress distributing were carried out by using the birth-and-death elements of the large finite element analysis software ANSYS and thermal-structural coupled numerical analysis technology to weld. The main contents are as follows:(1) This paper conducted a study of the techniques of welding of thick steel plate construction under low temperature operating conditions. A rigorous low-temperature welding test was conducted.The test included the welding materials, specifications and welding position.(2) By using the large finite element method software ANSYS, this paper analyzed the welding temperature field and the residual stress. The residual tensile stress came into being in the weld and the surrounding area, as high temperature heat source and move quickly after the cooling in the welding process. And also the thermal stress field and residual stress started up by this. To predicting welding distortion, this paper used the birth-and-death elements of the large finite element analysis software ANSYS and thermal-structural coupled numerical analysis technology to weld, obtaining weld residual stress temperature distribution.(3) The main innovation of this study is Electric preheating, soldering multi-layer multi-channel. Compared to flame heating the electric heating and has obvious advantages:As warm-up area is heated evenly, it is effectively to prevent the additional stress joints caused by local heating; Because of the heating rate is uniform and easy controlled, so it can prevent the phenomena of base metal overheating; In terms of the overall structure weld, it can prevent the deformation of components caused by the uneven heating.(4) Finally, this paper carried out economic and technical analysis. By using this method all the welds self, third-party testing in Qingdao Center Project of China Railway, Qingdao World Trade Center project had all pass rate. Application of the construction technology,it can ensure the normal construction, while ensuring the quality of the project, won acclaim form supervision of company owners, and achieved good economic and social benefits.