高能喷丸对R60702焊接接头组织性能影响

Effect of High Energy Shot Peening on Microstructure and Properties of R60702 welded joints

摘要:

采用表面高能喷丸工艺(HESP)对工业纯锆(R60702)焊接接头进行处理,利用金相显微镜(OM)、X射线衍射(XRD)和背散射电子衍射(EBSD)方法表征微观组织、表层晶粒尺寸、微观畸变、梯度结构和晶体取向,利用表面粗糙度测量仪测量评定表面粗糙度,利用电化学工作站研究了R60702焊接接头耐腐蚀性能。结果表明,工业纯锆焊接接头经HESP处理后,试样表层形成厚约110μm的梯度结构,最表层晶粒达到纳米量级；在表面纳米化过程中,孪晶和位错滑移是主要的变形方式；HESP处理后,R60702焊接接头自腐蚀电位正移,腐蚀电流密度降低；HESP处理使焊接接头三个区域的表层组织均一化,自腐蚀电位基本趋于一致,有效抑制了电偶腐蚀。

Abstract:

The welded joint of industrial pure zirconium (R60702) was treated by surface high energy shot peening (HESP). The microstructure, surface grain size, micro distortion, gradient structure and crystal orientation were characterized by optical microscope (OM), X-ray diffraction (XRD) and electron back scattered diffraction (EBSD). A surface roughness measuring instrument was used to measure and evaluate the surface roughness, and an electrochemical workstation was used to study the corrosion resistance of R60702 welded joints. The results showed that after HESP treatment, a gradient structure was formed on the surface layer of the industrial pure zirconium welded joints with a thickness of about 110 μm, and the grains of top layer reached the nanometer level; In the process of surface nanocrystallization, twins and dislocation slip were the main deformation methods; After HESP treatment, the self-corrosion potential of R60702 welded joints was positively shifted, and the corrosion current density was reduced; HESP treatment made the surface structure of the three areas of the welded joints uniform, and the self-corrosion potential tended to be uniform, which effectively inhibited galvanic corrosio.