大坡度山区管道焊接接头应力数值模拟研究OACSTPCD

The long-distance pipeline passes through mountains and hills,and the laying and welding process sometimes needs to be carried out at a 5°～45° slope.The pipeline in mountain areas with large slopes often fails due to excessive tensile stress,so its stress distribution becomes a necessary research topic.In this paper,the stress distribution of welded joints of X70 steel with a slope of 25° using automatic welding is studied.Based on the Thermal-Metallurgic-Mechanical theory,the finite element model of the welded joints of pipelines in mountainous areas with high slopes is established,and the actual heat source model and construction environment are taken as the boundary conditions.The welded joints are uniquely di-vided into higher and lower sides,and finally,the stress distribution is obtained,which fills the gap in the study of the stress distribution of welded joints in mountainous areas with large slopes.The hole-drilling method and the coercive method are used to measure the stress level of the inner and outer surfaces of the pipeline to verify the accuracy of the stress simulation.The welded joints are subjected to axial stress along the pipe due to gravity and supporting force.So the stress distribution of welded joints of pipelines in mountain areas with large slopes is different from that of pipelines without slope.The average width of the coarse-grained zone of the root welding layer of the higher side is 27 μm wider than that of the lower side.The average width of the coarse-grained zone of the hot welding layer of the higher side is 21 μm wider than that of the lower side.The tensile stress of the root welding layer of the higher side is 135 MPa higher than that of the lower side,and the high tensile stress zone of the root welding layer of the higher side is 1.6 mm wider than that of the lower side.