構造用合金鋼の疲労強度に及ぼすレーザ溶着処理の影響

抄録

Laser irradiation treatment is a surface hardening technique developed recently. It has been applied to the improvement of fatigue strength and the prevention of fracture of a cracked specimen etc. But few studies on the laser cladding method have been reported so far, though it is not only efficient to improve the fatigue strength but also can form a heat-, corrosion- and wear-resisting alloy layer on materials. In this paper, fatigue tests using two kinds of laser cladding specimens were carried out in order to investigate the cladding effect.
It was found that the fatigue life of the laser cladding specimens increased by 2-5 times as compared with the non-treatment specimen, but it was accompanied with a larger scatter in fatigue life and crack growth rate. The fractography on the fracture surfaces showed the existence of some defects (voids) in the cladding layer. These defects control the fatigue strength and cause the scatter. It was observed that the specimens without large defects were strengthened more notably.