抄録
The condition for occurrence of weld solidification cracking is analyzed in relation to strain rate by direct observation technique MISO for plain carbon steels, stainless steels and an Inconel alloy. All the materials used show a dependence of critical strain required for crack initiation on strain rate. Namely, the critical strain increases with an increase in strain rate. The dependence becomes bigger with a decrease in crack susceptibility. Therefore, the critical strain in a high strain rate is more likely to differentiate the crack susceptibilities among materials than in a low strain rate. On the other hand, the strain rate in Houldcroft-type cracking test and in case of some welding fabrications is shown to be so low that the difference of the critical strain among materials is little. Under such low strain rate, the critical strain rate below which the crack can not occur is useful for the comparison of crack susceptibilities.
