Investigation of Impact Strength, Micro Hardness and Metallurgical Analysis of DMLS Fabricated CoCrMo Alloy Samples

Many components in the mechanical industries fail more, due to the impact load rather than the stationary load. Essential knowledge on mechanical properties of materials is required for an engineer to develop a prototype using Direct Metal Laser Sintering (DMLS). It is an additive manufacturing technology which is extensively used for developing functional components and prototypes in mechanical, aerospace, marine and other Industries. In the present study, the material CoCrMo which is a cobalt based super alloy is sintered in vertical orientation (length in Z-direction) for testing the impact strength, micro hardness of the material by varying input parameters like laser power, scan speed and porosity, each three levels, to fabricate the standard samples. The microstructure of the fabricated samples is analysed by capturing the SEM images. The results obtained state that samples fabricated using moderate laser Power (310 W), low Scan Speed (1200 mm/s) and moderate porosity (20%) exhibit high impact strength (16 J/cm²) and the samples fabricated with moderate scan speed (1300 mm/s), high Laser power (350 W) and low porosity (10%) exhibits high micro hardness (506.37 ± 15). However, the sample surfaces doesn’t have porosity, the influence of the same is negligible on micro hardness. The reasons are discussed in detail. The experimental results indicate the suitability of DMLS fabricated CoCrMo components for different applications like bio-medical, aerospace engineering etc. where high micro hardness and impact strength are desirable.