An investigation was conducted to characterize the influence of welding variables, such as weld metal diffusible hydrogen content, on the hydrogen cracking resistance of HY-80 steel. The moisture pickup characteristics of several shielded metal-arc welding products were measured by the standard combustion technique. The weld metal diffusible hydrogen level corresponding to the electrode coating moisture was measured by gas chromatography.
Implant weldability tests were performed to quantify the cracking resistance of HY-80 steel under different combinations of weld metal diffusible hydrogen level and welding preheat/inter-pass temperature. Implant lower critical stress values were found to increase with a decrease in weld metal diffusible hydrogen content.
Self-restrained weldability tests (rigidly restrained cracking specimens) were performed at selected conditions determined on the basis of implant testing. The dimensions of rigidly restrained cracking specimens were varied between different tests in order to produce restraint levels that would result in cracking or no cracking situations based on implant lower critical stress values. The results of rigidly restrained cracking tests at reduced preheat temperatures (that is, 0° and 16°C) agreed with anticipated critical stress levels required for cracking as determined by implant lower critical stress values.