奥氏体不锈钢焊缝组织等轴晶化处理方法的研究

RESEARCH ON TREATING PROCEDURE OF EQUIAXED GRAIN CRYSTALLIZING FOR AUSTENITIC STAINLESS STEEL WELDING

为了改善焊管的耐腐蚀性和力学性能,将奥氏体不锈钢对接焊管经过拉拔减径预变形后,再用适当温度退火处理,从而使焊缝组织实现再结晶,即以不具方向性的等轴晶组织取代具有方向性很强的柱状晶(或柱状树枝晶)组织。结果表明,已等轴晶化的焊缝,不仅在组织形貌上变得和母材基本一致,而且耐腐蚀性也得到了提高。为了保证焊缝组织完全转变为细小的等轴晶组织,预变形量应在9．4％以上的减径率,并且最佳退火温区应在980～1 000℃以内。

In order to improve the corrosion-resistance and the mechanical properties of the welded pipe, the austenitic stainless steel butt welded pipe has been made to undergo a diameter reduction pre-deformation drawing and an annealing treatment at proper temperature. As a result of these, the welding seam structure recrystallization has occurred, ie the equiaxed grain structure has replaced the strongly directional columnar grain stueture （or columnar branch grain）, namely, equiaxed grain crystallization, The results also show, equiaxed grain crystallized weld not only becomes consistent with the matrix in microstructure appearance on the whole, but also becomes improved in corrosion-resistance- For the purpose of insuring the welding structure to be changed into fine equiaxed grain completely, the pre-deformation amount of the reduction diameter rate must be great than 9. 40%, and the optimum annealing temperature zone shouId be within 980-1000℃.