Mechanical Properties of Co-Cr Alloys for Metal Base Framework

Abstract

ABSTRACT Purpose This study investigated the effect of two welding methods on the mechanical properties of a cobalt-chromium (Co-Cr) alloy for metal base framework. Materials and methods Fifty-four plates were cast for TIG and laser welding. Cobalt-chromium for plates were prepared and divided into three groups of 18 samples. Group 1 and 2 were cut at the center of the plate. Eighteen specimens were joint by using TIG (Primotec Phaser Mx1), and other 18 by laser (Nd:YAG laser). Specimens in the as-cast condition were used as control group (group 3). After joining, each specimen was microscopic analyzed and tested to flexural and dynamic failure. Failure loads were recorded and fracture strength calculated. Results The changes in microstructure and micro-hardness were studied in the heat-affected zones (HAZ) and unaffected zones. Micro- hardness values increased in the heat-affected zone (HAZ) and in welded material compared to the parent material. The ANOVA test showed a highly significant difference (α = 0.05) between the joint strengths of the as-cast control specimens and, TIG and laser-welded joints. The flexural and dynamic strength of the joints were higher than those for the TIG-welded joints, and both were higher than the laser-welded joint strengths for the tested Co-Cr alloy. Conclusions Although laser is more popular, in our research TIG showed better results for flexural and dynamic strength.