Effect of Martensite Plasticity on the Deformation Behavior of a Low-Carbon Dual-Phase Steel

An experimental study has been conducted to quantify the effects of martensite plasticity on the mechanical properties of a commercial low-carbon (0.06 wt pct) dual-phase steel. The volume fraction and morphology (banded and more equiaxed) of the martensite second phase were systematically varied by control of the intercritical annealing temperature and the heating rate to this temperature. It was observed that the yield and tensile strengths were dependent on the volume fraction of martensite but not on the morphology. In contrast, the true uniform strain, fracture strain, and fracture stress were found to have a significant dependence on martensite morphology. These results were rationalized by considering an Eshelby-based model, which allowed for the calculation of the stress in the martensite islands for different morphologies and volume fractions. By comparing the stress in the martensite with an estimate of its yield stress, it was possible to rationalize the conditions under which martensite plasticity occurs. The implications of martensite plasticity affect the work hardening of the steels but most importantly the fracture properties. For conditions where martensite codeforms with the ferrite matrix, void nucleation is suppressed and the final fracture properties are dramatically improved.

[1]  T. Byun,et al.  Tensile properties and inhomogeneous deformation of ferrite-martensite dual-phase steels , 1993, Journal of Materials Science.

[2]  T. C. Lei,et al.  Microscopic deformation behaviour of martensitic–ferritic dual-phase steels , 1986 .

[3]  F. Pickering,et al.  Structure–property relationships in dual-phase steels , 1982 .

[4]  T. Gladman.  The Physical Metallurgy of Microalloyed Steels , 1997 .

[5]  W. Poole,et al.  Austenite formation during intercritical annealing , 2004 .

[6]  Ak Schmieder,et al.  Formability Topics—Metallic Materials , 1978 .

[7]  H. Klaar,et al.  Microstructure and properties of a C-Mn-Si-dual-phase steel , 1990 .

[8]  T. Gladman,et al.  Work hardening of dual-phase steels , 1981 .

[9]  H. Margolin,et al.  Plastic zone sizes and strain partitioning in α-β TiMn alloys , 1982 .

[10]  Kalyan Kumar Ray,et al.  Influence of martensite content and morphology on tensile and impact properties of high-martensite dual-phase steels , 1999 .

[11]  F. Zok,et al.  On the role of particle cracking in flow and fracture of metal matrix composites , 1995 .

[12]  J. Jonas,et al.  Strength of metals and alloys , 1985 .

[13]  George J. Weng,et al.  The overall elastoplastic stress-strain relations of dual-phase metals , 1990 .

[14]  J. Embury,et al.  Prediction of shear localization during large deformation of a continuous cast Al–Mg sheet , 2005 .

[15]  John W. Hutchinson,et al.  Particle reinforcement of ductile matrices against plastic flow and creep , 1991 .

[16]  L. Durand,et al.  Tensile deformation of a two-phase copper-silver alloy , 1981 .

[17]  D. Vanderschueren,et al.  Influence of run-out table cooling patterns on transformation and mechanical properties of high strength dual phase and ferrite–bainite steels , 2001 .

[18]  F. B. Pickering,et al.  Physical metallurgy and the design of steels , 1978 .

[19]  D. Matlock,et al.  On the deformation behavior of dual-phase steels , 1979 .

[20]  Rashid,et al.  Relationship between microstructure and formability in two high-strength, low-alloy steels , 1978 .

[21]  G. Weng,et al.  The influence of inclusion shape on the overall elastoplastic behavior of a two-phase isotropic composite , 1991 .

[22]  Gareth Thomas,et al.  On the law of mixtures in dual-phase steels , 1980 .

[23]  George Krauss,et al.  Void formation during tensile testing of dual phase steels , 1988 .

[24]  G. Thomas,et al.  Effects of morphology on the mechanical behavior of a dual phase Fe/2Si/0.1C steel , 1981 .

[25]  D. Bourell,et al.  Influence of martensite transformation strain on the ductility of dual-phase steels , 1983 .

[26]  R. Cahn,et al.  Constitution and properties of steels , 1992 .

[27]  W. C. Leslie,et al.  The physical metallurgy of steels , 1981 .

[28]  J. Gurland,et al.  Strain partition, uniform elongation and fracture strain in dual-phase steels , 1987 .

[29]  T. Öztürk,et al.  Strain partitioning and plastic flow in some metal/metal laminates , 1994 .

[30]  J. Embury,et al.  The deformation of CuW laminates , 1991 .

[31]  P. Thomason,et al.  Ductile Fracture of Metals , 1990 .

[32]  E. Werner,et al.  An unexpected feature of the stress–strain diagram of dual-phase steel , 2002 .

[33]  R. G. Davies.  Influence of martensite composition and content on the properties of dual phase steels , 1978 .

[34]  A. Marder.  Deformation characteristics of dual-phase steels , 1982 .