Formation of the anomalous microstructure in the weld metal of Co-based alloy/AISI 410 stainless steel dissimilar welded joint

The Co-based alloy/AISI 410 stainless steel dissimilar welded joint was fabricated by the electron beam welding(EBW)technique.The anomalous microstructure containing the element transition zone(ETZ)and/or core of tail-like zone(CTLZ)is in the weld metal(WM)adjacent to the fusion line.The melting temperature difference between the WM and AISI 410 steel,melt stirring effect and element diffusion can trigger the formation of such anomalous microstructure.In particular,the larger distance of the region in WM away from the fusion line,the smaller CTLZ and larger ETZ occurred.Compared with the fine and ellipsoidal precipitates in the as-welded CTLZ,a large number of chain-type clustered precipitates were detected in the CTLZ and ETZ interface after the aging treatment at 566°C for 1000 h.The element diffusion under elevated temperature in WM is regarded as the crucial factor for such anomalous microstructure evolution during the aging treatment.

AISI 410钢膏剂渗硼工艺渗层的组织与性能

通过膏剂渗硼工艺对AISI 410钢进行表面强化,分析了渗硼层的组织形貌,并测试了其硬度、耐磨损性能以及耐腐蚀性能。结果表明,渗硼层主要由FeB、Fe_(2)B相组成,渗硼层/母材的结合界面较平坦;渗硼层外渗区硬度达1400 HV0.5以上,内渗区硬度达1100 HV0.5以上;渗硼处理后试样表面摩擦因数和截面磨痕面积显著减小,耐磨损性能得到改善;在电化学腐蚀试验中,渗硼试样自腐蚀电位大于母材试样、自腐蚀电流密度小于母材试样,说明渗硼处理降低了AISI 410钢表面的腐蚀倾向,其表面耐蚀性得到提高。