18-8不透鋼熔接棒によるα係鋼材熔接の基礎研究(第2報)

Abstract

In the present report, relations between welding current, amount of penetration or penetration ratio of base metal to the austenitic stainless steel weld metal and hardness of austenitic weld metal and microstructure, etc., in each single bead which was deposited on four kinds of carbon steel plates with commercial 18-8 austenitic stainless steel electrode containing about 5 percent of manganese in core wire of 4 mm in diameter, were studied. D. C. reverse polarity was used. And welding speed and thickness of base metal were constant, 200 mm/min and 10. mm respectively. The results obtained are as follows:(1) Penetration variables such as the amount of penetration and penetration ratio, etc. tend to increase linearly as welding current increases. And in this case, the obtained penetration ratio increases from about 20 to 50 percent as welding current increases from 95 to 180 amperes.(2) Penetration ratio has a little tendency to increase, as carbon content of base metal increases.(3) Vickers hardness of austenitic stainless steel weld metal is comparatively lower (Hv is appro ximately from 200 to 220) for the range of smaller penetration ratio, but becomes higher (Hv is max. 400) as penetration ratio becomes larger. But in the case when penetration ratio is the same for the range of larger one, Vickers hardness of austenitic weld metal containing high carbon base metal is lower than that of the metal containing low carbon base metal. This result obtained in the present experiment is different from that of the Ist. report.(4) Micro-hardness at the side of austenitic stainless steel weld metal of the vicinity of weld fusion line increases, for the most part, linearly as welding current increases. Consequently, the above tendency of micro-hardness change is somewhat different from that of Vickers hardness change.(5) Both maximum Vickers hardness of the heat-affected zone in base metal and micro-hardness of the vicinity of weld fusion line of that same zone have a tendency to decrease as welding current increases.