金属焊接-图4-耐蚀钢3Ni-1在达叻现场腐蚀1年后的表面轮廓(a)母材，(b)热影响区，(c)焊缝。通过CO₂气体保护焊（250A， 29V， 300mm/min， 14.5 kJ/cm）。

对于1年试样, 3Ni-1焊接接头母材、熔合线和焊缝区均受到不同程度的腐蚀，表面布满了大大小小的点蚀坑。从点蚀坑的直径和深度来看，母材区、熔合线和焊缝区相差不大，说明3Ni-1焊接接头各部位腐蚀比较均匀，焊接接头耐蚀性好。对于2年试样，不同区域的腐蚀形貌不同，整体呈均匀腐蚀状态，相较于1年试样熔合线附近腐蚀更为严重。

Metal welding - Figure 4 - surface profile of corrosion resistant steel 3ni-1 after 1 year corrosion in Dalat site (a) base metal, (b) heat affected zone, (c) weld. Through CO2 gas shielded welding (250A, 29V, 300mm / min, 14.5 kJ / cm).

For one-year specimens, the base metal, fusion line and weld zone of 3ni-1 welded joint were corroded to varying degrees, and the surface was covered with pitting pits. According to the diameter and depth of pitting pits, there is little difference among base metal zone, fusion line and weld zone, which indicates that the corrosion of 3ni-1 welded joint is uniform and the corrosion resistance of welded joint is good. For 2-year specimens, the corrosion morphology of different areas is different, and the corrosion is uniform as a whole, which is more serious than that near the fusion line of 1-year specimens.