Investigation of Residual Stresses in Steel Weldments

摘要

Experimental hydrogen-induced-cracking tests were made on 45 weldments in mild steel, HY-80 steel, a commercial high-strength structural steel, and SAE 4340 steel. Extensive cracks were found in weldments made in SAE 4340 steel (oil quenched and tempered at 500 F) after hydrogen charging for relatively short times. Systematic crack patterns that could be related to residual stress distributions were obtained on various complex weldments. When steels of lower strengths were used, longer charging time was required to produce cracks, and crack patterns were less pronounced. The hydrogen-induced-cracking technique does not seem to work on mild-steel weldments. It has been found that hydrogen-induced cracking is stress sensitive rather than plastic-strain sensitive. This has been proved by hydrogen-induced-cracking tests on mechanically stress-relieved specimens and press-fit specimens in which residual stresses were produced by purely elastic deformation. It was found that distributions of residual stresses in mild-steel and SAE 4340 steel weldments were quite similar despite the considerable differences in the yield strengths of the two base plates and the weld metals. This was proved in butt joints up to 38 inches long and complex welded structures. (Author)