Thermomechanical and annealing processing effect on a rapid solidified Co – 20 wt. % Cr alloy

Abstract

The microstructure influence on the mechanical properties in a rapid solidified Co – 20 wt. % Cr alloy processed by hot – rolling (HR), and hot – rolling plus annealing (HR +A) is presented. The characterization consisted of a scanning electron microscopy inspection and its correlation with hardness, tensile test measurements and the corresponding fractography. The results showed that the as – cast (AC) condition is conformed by columnar dendrites aligned on a preferential direction. Additionally, numerous striations associated with the massive athermal transformation were observed. From the hot – rolled condition, athermal ε – martensite plates inside block austenitic grains were identified. On the other hand, the specimen subjected to hot – rolling plus annealing treatment showed an important internal stresses relief, reflected in the ductility improvement from 4.3 ± 2.18 % in the AC condition, and 13.73 ± 3.74 % in the HR condition to 27.8 ± 4.35 % for the HR + A condition.