板厚与取样位置对螺旋埋弧焊管母材拉伸性能的影响

Effect of Plate Thickness and Sampling Location on Tensile Properties for the Pipe Body of Spiral Welded Pipe

分析了某制管厂在采用L450MB卷板生产φ813 mm×12.5 mm和φ813 mm×11.0 mm规格钢管过程中,由于板厚和钢管母材取样位置不同而造成母材拉伸性能较原材料的变化情况,分析指出,由于材料受包申格效应的影响较大,管体母材的屈服强度相比原材料卷板下降了50~60MPa,抗拉强度下降大约10MPa,屈强比也有明显降低;壁厚较大的卷板在制成钢管的过程中,屈服强度和屈强比的下降值比壁厚较小的卷板有所减小;管体母材拉伸试验的取样位置在距螺旋焊缝a/2处时,其拉伸性能相对于在距螺旋焊缝a/4处取样时有所降低。

While adopting L450MB rolled coils to process SAWH pipe,being affected by the Bauschinger effect,yield strength of pipe body reduces 50~60 MPa compared to that of raw material,and the tensile strength reduces about 10 MPa,so yield ratio reduces obviously.The Bauschinger effect of rolled coils with 12.5 mm thickness is small,and the reduction values of yield strength and yield ratio are smaller.During the thermo-mechanical control process（TMCP）,becase of the smaller grain size of ingot edge,the rolled coils edge grain is also smaller and thus a higher strength.While the ingot center due to the segregation of impurity concentration and greater grain size,the strength of the middle part of rolled coils is lower.The properties difference along the width of rolled coils causes tensile property weaker away from weld a/2 distance than that of weld a/4 distance.