Microstructure-Property Relationship in the Thermomechanically Processed C-Mn-Si-Nb-Al-(Mo) Transformation-Induced Plasticity Steels Before and After Prestraining and Bake Hardening Treatment

Materials Science and Engineering: A

Shahrani

Zhu

et al. 2014

Section: Estimates Of Microstructural Contributions To Yield Stresssupporting

confidence: 90%

Effect of niobium clustering and precipitation on strength of an NbTi-microalloyed ferritic steel

Materials Science and Engineering: A

Shahrani

Zhu

et al. 2014

“…This is in contrast to the lowest precipitation strengthening contribution calculated for the MoNbV-steel subjected to the lower strain processing. The additional strengthening in this condition could originate from two sources: (i) solid solute atoms of Mo, C and, possibly, N; and (ii) atom clusters of Mo, Nb and V. Substantial strengthening from atom clusters was recently reported for microalloyed steels [80][81][82][83]. In spite of qualitatively similar effects of Mo and Cr on solubility of other elements, in the CrNbV-steel a possible strengthening from solute atoms and atom clusters did not exhibit itself.…”

Section: Microstructure-mechanical Properties Relationship: Role Of Smentioning

confidence: 78%

Comparative Effect of Mo and Cr on Microstructure and Mechanical Properties in NbV-Microalloyed Bainitic Steels

Singh

Chen

et al. 2018

Metals

Steel product markets require the rolled stock with further increasing mechanical properties and simultaneously decreasing price. The steel cost can be reduced via decreasing the microalloying elements contents, although this decrease may undermine the mechanical properties. Multi-element microalloying with minor additions is the route to optimise steel composition and keep the properties high. However, this requires deep understanding of mutual effects of elements on each other's performance with respect to the development of microstructure and mechanical properties. This knowledge is insufficient at the moment. In the present work we investigate the microstructure and mechanical properties of bainitic steels microalloyed with Cr, Mo, Nb and V. Comparison of 0.2 wt. % Mo and Cr additions has shown a more pronounced effect of Mo on precipitation than on phase balance. Superior strength of the MoNbV-steel originated from the strong solid solution strengthening effect. Superior ductility of the CrNbV-steel corresponded to the more pronounced precipitation in this steel. Nature of these mechanisms is discussed.

“…A decrease in UTS with a decrease in the precipitate number density has been shown previously for the Nbmicroalloyed line pipe steels [33] and TRIP steels. [38] The elongation to failure (ductility) increased with a decrease in the finish deformation temperature (Table II) inversely following the decrease in work hardening rate and UTS (strength).…”

Section: B Effect Of Tmp On Mechanical Propertiesmentioning

confidence: 99%

Strengthening Mechanisms in Thermomechanically Processed NbTi-Microalloyed Steel

Marenych

Killmore³

et al. 2015

Metall Mater Trans A

The effect of deformation temperature on microstructure and mechanical properties was investigated for thermomechanically processed NbTi-microalloyed steel with ferrite-pearlite microstructure. With a decrease in the finish deformation temperature at 1348 K to 1098 K (1075 °C to 825 °C) temperature range, the ambient temperature yield stress did not vary significantly, work hardening rate decreased, ultimate tensile strength decreased, and elongation to failure increased. These variations in mechanical properties were correlated to the variations in microstructural parameters (such as ferrite grain size, solid solution concentrations, precipitate number density and dislocation density). Calculations based on the measured microstructural parameters suggested the grain refinement, solid solution strengthening, precipitation strengthening, and work hardening contributed up to 32 pct, up to 48 pct, up to 25 pct, and less than 3 pct to the yield stress, respectively. With a decrease in the finish deformation temperature, both the grain size strengthening and solid solution strengthening increased, the precipitation strengthening decreased, and the work hardening contribution did not vary significantly. The effect of deformation temperature on microstructure and mechanical properties was investigated for thermomechanically processed NbTi-microalloyed steel with ferrite-pearlite microstructure. With a decrease in the finish deformation temperature at 1348 K to 1098 K (1075°C to 825°C) temperature range, the ambient temperature yield stress did not vary significantly, work hardening rate decreased, ultimate tensile strength decreased, and elongation to failure increased. These variations in mechanical properties were correlated to the variations in microstructural parameters (such as ferrite grain size, solid solution concentrations, precipitate number density and dislocation density). Calculations based on the measured microstructural parameters suggested the grain refinement, solid solution strengthening, precipitation strengthening, and work hardening contributed up to 32 pct, up to 48 pct, up to 25 pct, and less than 3 pct to the yield stress, respectively. With a decrease in the finish deformation temperature, both the grain size strengthening and solid solution strengthening increased, the precipitation strengthening decreased, and the work hardening contribution did not vary significantly.