Cyclic deformation behavior of a transformation-induced plasticity-aided dual-phase steel
- Shinsu Univ., Nagano (Japan). Dept. of Mechanical Systems Engineering
Recently, a new type of 600 to 1,000 MPa grade high-strength dual-phase sheet steel composed of a ferrite matrix and second phase (bainite plus retained austenite) was developed for the purpose of weight reduction of various automotive structural press parts. Here, cyclic hardening-softening behavior of a TRIP-aided dual-phase (TDP) steel composed of a ferrite matrix and retained austenite plus bainite second phase was examined at temperatures ranging from 20 C to 200 C. An increment of the cyclic hardening was related to (1) a long-range internal stress due to the second phase and (2) the strain-induced transformation (SIT) behavior of the retained austenite, as follows. Large cyclic hardening, similar to a conventional ferrite-martensite dual-phase steel, appeared in the TDP steel deformed at 20 C, where the SIT of the retained austenite occurred at an early stage. This was mainly caused by a large increase in strain-induced martensite content or strain-induced martensite hardening, with a small contribution of the internal stress. In this case, shear and expansion strains on the SIT considerably decreased the internal stress in the matrix. With increasing deformation temperature or retained austenite stability, the amount of cyclic hardening decreased with a significant decrease in plastic strain amplitude. This interesting cyclic behavior was principally ascribed to the internal stress, which was enhanced by stable and strain-hardened retained austenite particles.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 590076
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 12 Vol. 28; ISSN 1073-5623; ISSN MMTAEB
- Country of Publication:
- United States
- Language:
- English
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