Microstructure and its influence on mechanical properties of CLAM steel

The microstructure of China Low Activation Martensitic steel (CLAM) and its influence on mechanical properties were investigated. The tensile test showed that the strength of CLAM (HEAT 0603A) was higher than that of HEAT 0408B at room temperature, and the reverse results were obtained at elevated temperatures. The results indicated that the microstructure was composed of dispersived carbide particles and lath martensite with high dislocation density. The main precipitation phases were Cr-rich M23C6 carbides precipitated mainly along the lath boundaries and prior-austenite grain boundaries and Ta-rich MX particles precipitated mainly in the laths and lath boundaries. The finer lath was the main reason for the higher strength of HEAT 0603A compared with HEAT 0408B at room temperature; contrasted with the lower strength at high temperature. Heavier hot forging deformation degree was considered as the main possible reason for the decrease of martensite lath width in HEAT 0603A.