Study of Surface Integrity and Effect of Laser Peening on Maraging Steel Produced by Lasercusing Technique 2018-28-0094

In additive manufacturing, lasercusing is the selective laser melting technique. Finely pulverized metal is melted using a high-energy fibre laser, by Island principle strategy produces mechanically and thermally stable metallic components with reduced thermal gradients, stresses & at high precision. Maraging steel 300 (18Ni-300) is an iron-nickel steel alloy often used in applications requires high fracture toughness and strength. It maintains dimensional changes at a minimal level, e.g. aircraft and aerospace industries for rocket motor castings and landing gear or tooling applications. Current research attempts to analyze the effect of laser shock peening on lasercused material. Surface roughness of the material was found to be increased by 8%, due to effect of laser shock pulse & ablative nature. Also 8% increase in macro hardness on the surface. Depth wise micro hardness was investigated, found to be 9% increase on the sub layer of the material due to the effect of hardened martensitic matrix formed by precipitation hardening and grain size refinement attributed by laser shock peening. Yield & Ultimate tensile strength of the lasercused material is 9% & 12% higher than that of conventionally casted maraging steel. During tensile test, crack initiation occurred nearly at 45°, 21% percentage elongation, 36 mm² reduction in area. Obviously in fractographic analysis ductile mode failure is noticed, owing to the dispersive distribution of dimples and micro voids in the microstructure.