2012 年 30 巻 1 号 p. 42-49
Intergranular cracking due to liquid zinc embrittlement has sometimes occurred in heat affected zone (HAZ) of dissimilar welded joints of austenitic stainless steels with galvanized or zinc-plated carbon steels. In order to make clear the governing factors of cracking due to liquid zinc embrittlement in the heat affected zone of austenitic steels, the effect of chromium and nickel contents in the alloys on the intergranular zinc penetration was investigated in this study. From the results of the self-restraint U-type hot cracking test for zinc-coated austenitic alloys, the cracking susceptibility drastically changed at the certain value of the chromium/nickel contents. Especially, compared liquid zinc penetration behavior into grain boundaries between type304 stainless steel and Fe-36%Ni alloy, the zinc penetration was recognized only at grain boundaries in the stainless steel. On the other hand, the grain boundary energy in type304 stainless steel at elevated temperatures was about two times higher than that in Fe-36%Ni alloy. >From these results, it was concluded that the difference in susceptibility to intergranular cracking caused by liquid zinc embrittlement among alloys with various chromium and nickel contents was attributed to the change in grain boundary energy in these austenitic steels.