Dual-Phase, TRIP and TWIP Steels: Ductility by Microstructure Design
Advanced high-strength steels (AHSS) achieve an exceptional strength-ductility combination by engineering the metastable phases present in the microstructure. Three families dominate automotive applications.
Dual-phase (DP) steels (about 500-1000 MPa) consist of a soft ferrite matrix with about 5-20 percent martensite islands. Their high initial work-hardening comes from the stress transferred to martensite; the concept traces to Hayami and Furukawa (1975) and to Zackay et al. (1967), who first showed that retained austenite can enhance ductility in high-strength steels. Transformation-induced plasticity (TRIP) steels add 5-15 percent retained austenite that transforms to martensite during straining, postponing necking and raising uniform elongation. TWIP (twinning-induced plasticity) steels, typically Fe-Mn-(Al,Si), reach more than 600 MPa with more than 50 percent elongation via deformation twinning; GrasseL et al. (2000) established the Fe-Mn-Al-Si design and its automotive potential.
For stamping and crash components, DP and TRIP grades (for example EN 10338 HCT/HDT series, SAE CR series) reduce gauge and weight while improving crash energy absorption. JLHSteel can source AHSS strip and advise on press-shop springback control for these high-hardening materials.
References
1. Zackay, V.F., Parker, E.R., Fahr, D., Bush, R. (1967). The enhancement of ductility in high-strength steels. Transactions of the ASM 60: 252-259.
2. Hayami, S., Furukawa, T. (1975). Microstructures and properties of dual-phase steels. Microalloying 75.
3. GrasseL, O., Krueger, L., Frommeyer, G., Meyer, L.W. (2000). High strength Fe-Mn-(Al,Si) TRIP/TWIP steels development - properties - application. International Journal of Plasticity 16: 1391-1409. https://doi.org/10.1016/S0749-6419(00)00020-1
4. Jacques, P.J., et al. (2009). Multikinetik TRIP steels. Advanced Engineering Materials 11(7): 549-555.
Dual-phase (DP) steels (about 500-1000 MPa) consist of a soft ferrite matrix with about 5-20 percent martensite islands. Their high initial work-hardening comes from the stress transferred to martensite; the concept traces to Hayami and Furukawa (1975) and to Zackay et al. (1967), who first showed that retained austenite can enhance ductility in high-strength steels. Transformation-induced plasticity (TRIP) steels add 5-15 percent retained austenite that transforms to martensite during straining, postponing necking and raising uniform elongation. TWIP (twinning-induced plasticity) steels, typically Fe-Mn-(Al,Si), reach more than 600 MPa with more than 50 percent elongation via deformation twinning; GrasseL et al. (2000) established the Fe-Mn-Al-Si design and its automotive potential.
For stamping and crash components, DP and TRIP grades (for example EN 10338 HCT/HDT series, SAE CR series) reduce gauge and weight while improving crash energy absorption. JLHSteel can source AHSS strip and advise on press-shop springback control for these high-hardening materials.
References
1. Zackay, V.F., Parker, E.R., Fahr, D., Bush, R. (1967). The enhancement of ductility in high-strength steels. Transactions of the ASM 60: 252-259.
2. Hayami, S., Furukawa, T. (1975). Microstructures and properties of dual-phase steels. Microalloying 75.
3. GrasseL, O., Krueger, L., Frommeyer, G., Meyer, L.W. (2000). High strength Fe-Mn-(Al,Si) TRIP/TWIP steels development - properties - application. International Journal of Plasticity 16: 1391-1409. https://doi.org/10.1016/S0749-6419(00)00020-1
4. Jacques, P.J., et al. (2009). Multikinetik TRIP steels. Advanced Engineering Materials 11(7): 549-555.
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