锰对脉冲燃烧型焊条立焊接头组织性能的影响

用脉冲燃烧型焊条对Q235钢进行了手工自蔓延立焊焊接,研究了焊条锰含量对立焊接头组织性能的影响.结果表明,脉冲燃烧型焊条中未添加锰时,起焊位置没有形成有效熔池且焊缝中有大量气孔；锰含量低于5.9％(质量分数)时锰含量越高焊缝成形越好,焊缝中气孔迅速减少,焊缝以富铁相为主且富铁相占比随锰含量增加而增加,接头力学性能升高.锰含量为5.9％(质量分数)时接头力学性能最高,抗拉强度可达421MPa,显微硬度可达1 578.8 MPa.锰含量超过5.9％(质量分数)时,锰含量增加使得熔池向下流动严重形成焊瘤,甚至烧穿母材,焊缝以富铜相为主且有大量裂纹出现,力学性能迅速降低.

Influence of Mn on microstructure and properties of vertically welded joint with pulse combustion welding rod

Q235 steel was welded by manual high-temperature synthesis (SHS) vertical welding process with pulse combustion welding rod,and the influence of Mn content on the microstructure and properties of the resultant joints were studied. The results show that,without adding Mn in the pulse combustion welding rod,massive pores appeared in the weld without forming effective weld pool at the starting position of welding. When the Mn content was less than 5.9 wt%,the higher the Mn content was,the better the weld was shaped,and the pores reduced rapidly. Fe-rich phases dominated in the weld with the proportion increasing with the increase of Mn content,and the mechanical properties of the joints also increased. When the Mn content was 5.9wt%,the mechanical properties of the joints reached the optimum with tensile strength of 421 MPa and microhardness of 1 578.8 MPa. When the Mn content exceeded 5.9wt%,the increase of Mn content resulted in the weld pool flowing downward seriously and forming welding beading or even burning through the substrate. The resulting weld mainly comprised Cu-rich phases with lots of cracks,which deteriorated the mechanical properties of the joint.