The Research Of Modification Of Spray Fusing On Improving The Fatigue Performance Of Welded Construction

Fatigue fracture is the most important failure mode. And most of endurance failures of welded construction are occurred in the toe of weld. Stress concentration and welding residual stretching stress are the main reasons of the failure. Mostly, the fatigue value of welded splice is well inferior to the value of parent metal. So the fatigue value of the welded construction is dependent on the fatigue strength of the parent metal. Improving the fatigue strength is one of research hotspot for some experts at home and abroad. Now, the reports about the research of modification of spray fusing on improving the fatigue strength of welded construction are not found yet.After being modified through spray fusing, the knuckle radius of the toe zone became larger.Conclusions can been drawn by high cycle fatigue testing: 2×106 offset endurance strength of welded joint is 146.5MPa, 2×106 offset endurance strength of the welded joint spray fused by Ni60 is 241MPa, increased by 64.5%. 2×106 offset endurance strength of the welded joint spray fused by Fe38 is 208MPa, 42% more than welded joint.The fatigue strength of welded joint which the number of stress amplitude corresponding to the fatigue strength of the joint sprayed by Ni60 and Fe38 at 107 cycles. Cursory estimate can be drawn: the fatigue strength of the joint sprayed by Ni60 is increased by 20 times than the strength of welded joint; the fatigue strength of the joint sprayed by Fe38 is increased by 11 times than the strength of welded joint. Finite element model of welded joint, welded joint sprayed by Ni60, welded joint sprayed by Fe38 are built. stress concentration factor of welded joint is 2.4613,and welded joint sprayed by Ni60 is 1.0459, and welded joint sprayed by Fe38 is 1.5504. Stress concentration factors influenced by aspect ratio, height of welding line and knuckle radius of toe of weld were analyzed through finite element analysis. Conclusions can be drawn: the main reason of improving fatigue strength by modification of spray fusing is the decrease of the knuckle radius of toe of welded joint.