超声冲击处理对S32101双相不锈钢焊缝残余应力及组织的影响

Effect of UIT on residual stress and microstructure of S32101 duplex stainless steel weld

对S32101双相不锈钢焊后进行超声冲击处理,观察超声冲击处理前后母材及焊缝的组织形貌,采用XRD应力测试仪分析超声冲击处理前后焊缝及其附近的残余应力分布,并利用硬度计对焊缝截面进行硬度测试.结果表明,超声冲击处理后母材和焊缝都发生了塑性变形,母材中的铁素体组织被细化,奥氏体被拉长、破碎;焊缝表面的组织产生塑性变形,魏氏体状奥氏体和晶内奥氏体被细化,且被细化的晶粒均匀分布在焊缝表层,超声冲击处理强度为10 s/cm2时效果最佳,可将600 MPa的拉应力转化为600 MPa的压应力.超声冲击处理过后表层的硬度分布更加均匀且硬度值提高了50~90 HV.

Microstructure of the base metal and weld of S32101 duplex stainless steel were observed before and after ultrasonic impact treatment(UIT).Its residual stress distribution was analyzed by XRD stress tester,and the hardness of the weld section was tested using an hardness tester.The results show that the base metal and the weld are plastically deformed after UIT,ferrite in the base metal were refined,austenite is elongated and broken;microstructure of the weld surface shows plastically deformation characterization,the austenite and intragranular austenite are refined,and the refined grains are evenly distributed on the surface of the weld.The UIT effect is the best at 10 s/cm2,under the condition of which the tensile stress of 600 MPa can be converted into compressive stress of 600 MPa after the impact,hardness distribution of the surface layer is more uniform and the hardness value is increased by 50~90 HV.