Microstructure and Properties of Ultrafine-Grained Steel Produced by Warm Compression of Martensite
Specimens of medium carbon steel were quenched and warm-compressed on a Gleeble 3500 Machine. The microstructure of the specimens was studied by using an optical microscope and a transmission electron microscopy. And the properties were investigated by using tensile tests and hardness tests. Results show that the starting microstructure is lath martensite with a small amount of flake martensite. After 50% compression at 550-650°C, ultrafine grains can be observed in the specimens. The microstructure of the specimens compressed at 600°C is equiaxed ultrafine ferrite grains + nano-carbides and a good combination of strength and ductility is obtained. The tensile strength and total elongation are 861MPa and 19.1%, respectively. The hardness is 233.81Hv.
Jing Tao Wang
X. Zhao et al., "Microstructure and Properties of Ultrafine-Grained Steel Produced by Warm Compression of Martensite", Materials Science Forum, Vol. 682, pp. 205-209, 2011