すみ肉溶接割れに関する研究 : ヒールクラックについて

概要

論文の詳細を見る
Heel crackings occurring from the root of T-joint are often found in fillet welds of 50kg/(mm)^2 grade high strength steels. These crackings constitute a serious problem for the fillet weld of these steels. These crackings can be reproduced in laboratories by a non-restraint T-type cracking test method. With a view to determining the nature and causes of heel cracking formation, we conducted various experiments. The test results obtained are summarized as follows : (1) Heel cracking is one of the hydrogen induced crackings and shows the tendency of delayed cracking. (2) As to the stress causing heel cracking, the mismatching of vertical pate caused by the thermal expansion and shrinkage must be taken into consideration. (3) As a factor representing the sensitivity of 50kg/(mm)^2 grade high strength steels to heel cracking, P_N value is proposed. (4) Decarbonized surface layer of steel plate is effective for preventing heel crackings, which indicates that as-rolled steels are more crack-sensitive than the normalized steels and the quenched and tempered steels. (5) Heel crackings are different from lamellar tears usually considered. (6) Electrodes with low hydrogen content and low yield strength are effective for the prevention of heel crackings.
1972-08-25