Secondary hardened bainite

Abstract

The effect of Mo additions on the development of bainitic ferrite in hot rolled low carbon (0?05 wt-%C) Nb containing steel strips has been studied. The steel strips were fabricated by a combined process of controlled rolling and accelerated cooling. Microstructural characterisation and mechanical testing for the corresponding strips were investigated. The results indicated that a small amount of Mo addition (0?1-0?3 wt-%) causes the production of a high volume fraction of bainite, which undergoes significant secondary hardening after tempering treatment at 600uC for 1 h. It is noticeable that the secondary hardening effect provides an additional way to significantly increase the strength of low carbon Nb-Mo containing bainitic steels.

Crystallographic analysis of lenticular martensite in Fe–1.0C–17Cr stainless steel by electron backscatter diffraction

“…The following misorientation profiles show the accumulated point to origin The present pole figure investigation supports the view point of the paper [28] and disagrees on that of the paper [19], which claims that the spread is caused by a trace [29].…”

Nano-sized precipitation and properties of a low carbon niobium micro-alloyed bainitic steel

“…Therefore, strength contributed by nano-sized precipitates is almost equal with improvement of yield strength for samples after tempering in the present work. In addition, Previous studies [24][25][26] have suggested that MC-type nano-scale precipitates formed in ferrite always have the coherence relationship with surrounding ferrite matrix. Precipitation strengthening can be commonly explained by the Ashby-Orowan mechanism, as given by the following Eq.…”

“…Huang and Yang [24] studied the evolution of dislocation for low carbon micro-alloying steel on tempering. Their results have revealed that the decrease in the dislocation density in granular bainitic structure after tempering at 600°C even for 8 h is extremely small.…”

Tracing Microalloy Precipitation in Nb-Ti HSLA Steel during Austenite Conditioning

“…Colder finishing conditions promoting bainite formation largely prevent niobium precipitation. Secondary heat treatment such as tempering, however, allows nearly complete precipitation [23]. niobium precipitation.…”