Grain Refinement in Dual-Phase Steels

被引:90
作者
Mukherjee, K. [1 ]
Hazra, S. S. [1 ,2 ]
Militzer, M. [1 ]
机构
[1] Univ British Columbia, Ctr Met Proc Engn, Vancouver, BC V6T 1Z4, Canada
[2] Univ Wollongong, Dept Mech Mat & Mechatron Engn, Wollongong, NSW 2500, Australia
来源
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE | 2009年 / 40A卷 / 09期
基金
加拿大自然科学与工程研究理事会;
关键词
LOW-CARBON STEEL; INDUCED FERRITE TRANSFORMATION; ULTRA-FINE FERRITE; MICROSTRUCTURE EVOLUTION; HOT STRIP; DEFORMATION; STRAIN; NUCLEATION; AUSTENITE; TEXTURE;
D O I
10.1007/s11661-009-9899-9
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Deformation-induced ferrite transformation (DIFT) was applied in laboratory tests to produce fine-grained dual-phase (DP) steels. Four different chemistries were investigated, starting from a conventional DP 600 chemistry of 0.06 wt pct C-1.9 wt pct Mn-0.16 wt pct Mo and subsequently varying Nb and Mo additions. For all investigated steels, ultrafine ferrite (UFF) with a grain size of 1 to 2 mu m can be obtained when a sufficient amount of deformation (e.g., a true strain of 0.6 or above in axisymmetric compression) is applied to an austenite microstructure with a grain size in the range of 10 to 20 mu m at 25 A degrees C to 50 A degrees C above the austenite-to-ferrite transformation start temperature (Ar (3)) characteristic for the given cooling condition. Rapid post-deformation cooling at rates of approximately 100 A degrees C/s yields the desired UFF-martensite microstructure. Electron backscattered diffraction (EBSD) mapping reveals a high percentage (approximately 40 pct) of low-angle boundaries in these microstructures, except for the steel that is just microalloyed with Nb. The steel with the plain-carbon-base chemistry was subjected to hot torsion simulations of a hot strip rolling processing schedules that incorporate a DIFT pass after a conventional seven-stand finish mill schedule. Executing the DIFT pass at 650 A degrees C to 675 A degrees C produced an UFF microstructure, illustrating the potential for the design of novel thermomechanical processing paths to produce hot-rolled ultrafine DP steels.
引用
收藏
页码:2145 / 2159
页数:15
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