Research about the Effect of Residual Stress on the Fatigue Life of Cruciform Joint of 16MnR Steel

Surface treatment was carried out on the cruciform joint of 16MnR steel by using the HJ-II-type ultrasonic impact machine. The impact current is 1.2A, impact amplitude is 30 microns. Fatigue experiments were carried out for impact treated specimen, impact treated and heattreated specimen and un-heattreated specimen. The effect of ultrasonic impact on the hardness of the weldment and weld toe was researched. The experimental results show that the fatigue life of the cruciform joint of 16MnR steel can be significantly improved through the ultrasonic impact treatment and the hardness of weld toe can also be promoted. Compared to the sample without impact treatment, its fatigue life was increased 692.52%. The hardness of weld toe was increased 31%. Compared to the sample with heat treatment, the fatigue life of impact specimen was increased 316.67%. Compared to the sample without impact treatment, the fatigue life of impact and heat treated specimen was increased 218.69%.