Microstructure and mechanical properties of additively manufactured CoCrW alloy using laser metal deposition

Abstract

We successfully used CoCrW alloy as the feedstock for directly shaping wear-resistant products by additive manufacturing. We present a guideline for forming substantive, high-density, crack-free CoCrW alloys via laser metal deposition (LMD) and evaluated the relationship between the microstructure and mechanical properties. CoCrW alloy with a scale of several tens of cubic centimeters has not been previously reported because the brittle material undergoes cracking due to residual stresses. Densification and crack suppression were achieved by controlling the oxygen concentration in an Ar atmosphere and preheating the base plate to 400 °C. The tensile strength (MPa) of the LMDed CoCrW alloy was 1492 ± 141 along the scan direction, 1464 ± 234 along the overlap direction, and 1359 ± 72 along the build direction. The overlap direction had almost the same strength as the scan direction. In the microtensile test for the overlap direction, the fracture ratio in the overlap region was only 17.4%, and it was found that softening in this region did not contribute to the decrease in strength.