Ziyong Hou

Low density steel 1·2C–1·5Cr–5Al designed for bearings

Abstract A novel alloy design, designated as 1·2C–1·5Cr–5Al, has been proposed with high aluminium(∼5 wt-%) and more carbon(∼1·2 wt-%) addition into the classical 1C–1·5Cr bearing steel for lowering density and improving performance simultaneously, which is approximate 8 wt-% lighter than convention. In order to understand preliminarily the suitability of the novel alloy for bearing application, the martensite starting temperature and hardness, related to microstructure evolution and mechanical properties, respectively, after partial austenitisation treatment with undissolved carbides have been investigated carefully. The martensite starting temperature is comparable with conventional 1C–1·5Cr alloy. The hardness of 860±3 HV20 achieved is much higher than convention.

Effect of Coil Temperature on Microstructure and Texture Evolution of an High Strength Nb-IF Steel Sheet

Effect of coil temperature on the texture and microstructure evolution during cold rolling and annealing were investigated by OM, ODF and EBSD. The results indicate that the {223}<110> and {114}<110> textures appeared after cold rolling are inherited followed by annealing, whose intensities would be higher as the coil temperature decreased. Lower coil temperature could improve the uniformity of grain size and increase the fraction of low-angel grain boundaries as well as coincidence site lattice boundaries. And the {111}//ND texture is improved in the lower coil temperature cold and annealing steel sheet, which is beneficial for the deep-drawability.

Study of Microstructure and Texture of Nb-IF High Strength Steel after Cold Rolling and Annealing

The effects of annealing routes (batch annealing and continuous annealing) on the development of microstructure and texture in a cold-rolled Nb-IF high strength steel sheet were studied by means of optical microscopy(OM), electron backscattered diffraction(EBSD) and ODF analysis. The results show that the finer and more homogenous recrystallization grain can be observed in the CA steel. The CA process leads to an increase in the intensity of the γ-fibers, and the very sharp and uniform γ-fibers are found in this case, which is beneficial to the deep-drawability.

Microstructure and Mechanical Properties of ULCB Steels affected by advanced TMCP Technology

Good combination of high strength and high toughness has been considered as a critical factor of ultra-high strength steel plates. In this paper, a novel high strength steel plate of HSLA type containing Cu with 910MPa yield strength and 1163MPa tensile strength has been developed using an advanced TMCP (thermo-mechanical control processing) technology. The steel plates provide excellent combination of high strength, toughness and deformability. Microstructural evolution and mechanical properties of this steel during hot-working have been investigated. It is demonstrated that, at the relatively higher finish rolling temperature and cooling rate, the microstructure consists of acicular and granular bainite structures and a small amount of low bainite /martensite whose lath width is approximately 200~300nm. For the as-rolled conditions, despite the high strength and so low yield ratio, impact energy about 154J and fully ductility fracture at -90°C can still be obtained as documented for as-hot rolled plates.