Effect of Local Laser Surfacing on the Fatigue Crack Propagation Rate of Al-alloy 6056 and its Laser beam Weld

Abstract

A new surfacing method based on the laser melting was investigated in this study in order to improve the fatigue crack propagation performance of high strength al-alloy and its laser beam weld. The main objective was to reduce the Fatigue Crack Propagation (FCP) rate and increase the fatigue life of Al-alloy welded structure. The fatigue crack propagation rate of Al-alloy 6056 was assessed using CT-100 specimen including base material, base material with Local Laser Surfacing (LLS), laser beam weld and laser beam weld with LLS respectively. The results show a significant reduction in fatigue crack propagation rate with LLS treatment because the fatigue crack retardation phenomenon is obvious when the fatigue crack close to or meet the laser surfacing lane. The fatigue life of BM with LLS specimen is higher than that of BM specimen. For the LBW, there shows same results. That is FCP rate of the specimen of laser beam weld with LLS treatment shows significant reduction compared with the specimen of laser beam weld without LLS treatment. The facture surface and microstructure of LLS and LBM were observed also in order to explain the basic mechanism of LLS improving the fatigue life.