Study on the Crack Sensitivity of Mild Steel Welded Joint by Underwater Welding

Abstract

The crack sensitivity of underwater welded joints of mild steel in various thickness was experimentally investigated by CTS and Y-groove cracking tests in shallow water, using coated electrodes.
From these experiments the following results were obtained:
1) Cracks in heat affected zone of CTS and Y-groove cracking test specimens increased with decrease of plate thickness.
2) Cooling rate and maximum hardness of welds of CTS and Y-groove cracking test specimens increased with decrease of plate thickness.
3) The reason of increase of cooling rate of underwater welds with decrease of plate thickness was explained by a calculation by a considering heat transfer coefficient from surface of welds into water.
4) Diffusible hydrogen content of underwater deposited metals was about 41.5-43.7 cc/100 g.