SS400钢对接接头表面纳米化及其对疲劳强度的影响

Surface Nanocrystaillzation of SS400 Steel Butt Welded Joint and Its Effect on the Fatigue Strength

关键词:  对接接头  高能喷丸  表面纳米化  疲劳强度

Key words:  butt-welded joint  high energy shot peening  surface nanociystallization  fatigue strength

摘要:

采用高能喷丸技术对SS400钢对接接头的表面进行处理,利用X射线衍射和透射电镜对表层进行结构表征,并测量了对接接头表层硬度、残余应力和疲劳强度的变化。结果表明,高能喷丸处理可以在对接接头的表面形成尺寸均匀、晶粒取向呈随机分布的纳米晶组织,从而消除了对接接头表层组织的不均匀性;纳米结构表层的硬度明显高于心部,其内部残余应力为压应力。这种压应力纳米强化层可以明显地提高对接接头的疲劳性能。

Abstract:

The welded joint of SS400 steel was treated by high energy shot peening (HESP) technique, the surface layer was characterized by means of the XRD and TEM,and the changes of hardness, residual stress and fatigue strength were examined.Experimental results showed that nanostructured surface layer might form in the surface layer of welded joint after the HESP treatment, of which the crystallographic orientations were nearly random; therefore uniform microstnzcture could be obtained.The microhardness of the nanostructurcd surface layer was found to be much higher than that of the sample before the HESP treaiment,and the welding residual stresses in this layer became entirely compressive.This kind of nanostructured surface layer with compressive stress could significantly increase the fatigue strength of butt-welded joint.