Practicability Research on Low-match Weld Joint of High-Strength Steel

In this paper,low-match electrode was employed to weld high-strength steel and a series of tests with the welded joints were conducted including hardness,strength,bend,tenacity and antidetonating quality.The result indicated that for the low-match weld joint of steel with yield strength exceeding 1,000MPa,the conventional control processing of excess weld metal would lead to such undesirable situation:firstly,under tention stress,weld joint without excess weld metal would yield prior to base metal with low ductile fracture accompanying its restrainedly strengthened by higher strength HAZ and base metal,secondly,under bending stress or combined tention with bend,low-stress failure with plastic deformation would occur for the joints with excess weld metal.The essential reason of such situation lays to the insufficient plastic deformation resistence of soft weld.The base metal experienced little plastic deformation when the low-stress low ductile failure occurred in the weld metal,resulting relatively low stress bearing and lower energy absorbing ability,which are undesirable for the capacity of weld joint system in service.So it is very important to increase the plastic deformation resistence of soft weld to avoid plastic deformation concentration in joint.One way is to optimize design excess weld metal of this type joint to obtain equivalent weld joint to conventional full-strength or high-strength match joint,according to maximum shearing sress criterion.