Fatigue strength improvement of lap welded joints by low transformation temperature welding wire - superior improvement with strength of steel

摘要

The potential improvement in fatigue performance of lap welded joints in 2mm thick 540MPa and 780MPa class steels from the introduction of compressive residual stress by welding with low transformation temperature (LIT) welding wire was investigated. Comparative fatigue tests in bending at a stress ratio of R=0 on specimens made with conventional and LTT welds confirmed that the fatigue performance of such thin specimens was improved, particularly in the long-life regime. Furthermore, the benefit was greatest in the high-strength steel, the improvement in fatigue strength at 10{sup}7 cycles being 1.4 times for 540MPa steel and 1.6 times for 780MPa steel.