卷管铺设法对钢管力学性能的影响

Influence of reeling on mechanical properties of steel pipe

综述了近年来普遍采用的全尺寸、小尺寸试验和有限元模拟三种常见方法来研究卷管式铺设前后管材的显微组织和力学性能的变化,重点关注了卷管过程对焊接区力学性能的影响。研究表明:卷管铺设过程会降低管材塑性,但硬度和抗拉强度影响不大,由于形变强化和包辛格效应的联合作用,管材的屈服强度会发生显著变化,升降取决于最后的塑性变形是拉伸还是压缩;在焊缝热影响区卷管铺设过程会导致软化现象和应力集中,屈服强度大幅降低且加速裂纹扩展,焊缝处断裂韧性最低,但管材表面均未出现裂纹;卷管铺设过程会加重管材缺陷处的裂纹扩展及管材的椭圆化。然而目前主要研究对象都为现有钢种,而卷管铺设专用钢管开发还需进一步深入系统研究。

Three common methods,consisting of full-scale,small-scale experiments and finite element simulation,are introduced.The modification of microstructure and mechanical properties of pipes before and after reeling was investigation,and then the effect of rolling process on the mechanical properties of welding zone was focused.The research shows that the reeling can reduce the plasticity of the pipe,but little role on the hardness and tensile strength.Owing to the combined effect of the deformation strengthening and the Bauschinger effect,the yield strength of the pipe will change significantly.The increase or decrease of the yield strength depends on whether the final plastic deformation is tension or compression.The reeling in the heat affected zone of the weld will lead to softening and stress concentration,greatly reducing the yield strength and accelerating the crack propagation.The fracture toughness of the weld metal is the lowest,but no cracks appear on the surface of the pipe.The reeling will aggravate the crack propagation at the defect and the ovalization of the pipe.However,the main research objects are the existing steel grades at present,and the development of special steel pipe for the reeling still needs further research.