Fatigue Crack Propagation and Fracture Toughness of Laser Rapid Manufactured Structures of AISI 316L Stainless Steel

Fatigue crack propagation, fracture toughness, and impact toughness of AISI 316L stainless steel fabricated by laser rapid manufacturing with a continuous wave CO2 laser have been systematically studied. Charpy impact toughness of laser rapid manufactured structures was found to be on par with its wrought counterpart. Steady state fatigue crack growth rate in laser rapid manufactured compact tension specimens of AISI 316L stainless steel, in the investigated stress intensity range (ΔK) of 11.4-24 MPa √m, was comparable to that of 20% cold worked wrought AISI 316 stainless steel. Fatigue crack propagation was found to be transgranular in nature. The initiation fracture toughness (J 0.2) was found to be in the range of 147-259 kJ/m2 while critical crack tip opening displacement (CTODc) fracture toughness values were found to be in the range of 0.5-0.64 mm. Fracture toughness values of laser rapid manufactured structures, although inferior to wrought 316 stainless steel, were comparable to that of its weld metal. © 2014 Springer Science+Business Media New York and ASM International.