Abstract
Ferritic-martensitic steel with several welding methods in LBE were observed. The material was welded HCM12A. The specification of TIG, YAG laser and electron beam welding were 40A/12V of electrical conductance, 278W/14.3J of heat input and 5.0 mA of beam electric current, respectively. The stagnant corrosion test was conducted in liquid LBE at 600°C for 500 h. Oxygen concentration was controlled to be ∼4.7x10-6wt% by using Ar-H2-H2O mixed gas. After corrosion test, cross sections of the specimens were analyzed by using optical microscope and SEM/EDX. In order to know the hardness profiles of fusion zone and base metal were observed by using Vickers hardness tool. The results show coarse grain structure around fusion zone and typical ferritic-martensitic grain structure in base metal. It was found that Cr-rich spinel oxide layer and diffusion zone formed on the surface. However, it appears much thicker in the fusion zone, about 18-30µm, with respect to the base metal (10-15µm). The hardness number increase in fusion zone.
