In situ observation for the fatigue crack growth mechanism of 316L stainless steel fabricated by laser engineered net shaping

For the first time, the fatigue crack growth resistance of 316L stainless steel, fabricated by laser engineered net shaping (LENS) process, was investigated through in-situ SEM. The fatigue crack growth rate (FCGR), loading direction perpendicular to building direction (BD), was slightly slower than that of the parallel case and conventional 316L, when the fatigue crack approached the layer bands. In the area of non-layer band, the FCGRs for three cases were comparable, which was rarely affected by the elongated grain morphology. This FCGR characteristic in LENS process was different from the 316L manufactured by selective laser melting (SLM) and it was believed that this phenomenon is mainly attributed to the texture characteristic and microstructure in the presented material.