Continuous cooling transformation behaviors of CLAM steel

The continuous cooling transformation (CCT) behaviors of CLAM (China Low Activation Martensitic) steel were studied, the CCT diagram was constructed, and the influence of cooling rates on the microstructures was also investigated. The microstructures were investigated using optical microscopy (OM) and microhardness tests were also carried out. The results showed that CLAM steel possessed high hardenability and there were ferrite and martensite transformation regions only. The maximum cooling rate to form ferrite microstructure was found to be 10-12 K/min. In order to obtain fully ferrite microstructure, the cooling rate should be lower than 1 K/min. The CCT diagram also gave relevant parameters such as the transformation temperatures, i.e., Ac1, Ac3, Ms and Mf were 1124 K, 1193 K, 705 K and 593 K, respectively. The diagram made it possible to predict the microstructures and properties of CLAM steel with different cooling rates.