SS400钢焊接接头表层组织纳米均一化及硬度均一化处理

HOMOGENIZATION OF MICROSTRUCTURE AND HARDNESS OF SURFACE LAYER OF SS40O STEEL WELDED JOINT

采用高能喷丸技术对 ＳＳ４００钢焊接接头的表面层进行处理 利用 ＸＲＤ，ＴＥＭ，ＳＥＭ对处理后的表面层进行结构表征，同时测量了高能喷丸引起的硬度变化 结果表明，高能喷丸处理可使焊接接头的表面层形成尺寸均匀、取向随机分布的纳米晶；焊接接头三个区域的纳米层硬度一致，且远高于高能喷丸处理前样品的硬度，实现了 ＳＳ４００钢焊接接头区表层组织纳米均一化和硬度均一化 表面纳米化对材料表面的强化有着重要的贡献。

The surface layer of the welded joint of SS400 steel was treated by high-energy shot peening (HESP) technique, and characterized by means of the XRD, TEM and SEM. The hardness variation along the depth of the treated sample was examined after treatment. Experimental results show that the coarse-grained microstructure of top-surface layer of welded joint can be refined into nano-scale after the HESP treatment, and these nanocrystalline grains are about 10 mn in diameter and possess nearly random crystallographic orientations. The same hardness can be found for the nanostructured surface layers of the base metal, HAZ and weld of SS400 steel respectively, which is much higher than that of the sample before the HESP treatment. Homogenization of microstructure and hardness of the surface layer of SS400 steel welded joint are achieved. The strengthening of the surface layer can be primarily attributed to the surface nano crystallization.