Impact of Martensite Spatial Distribution on Quasi-Static and Dynamic Deformation Behavior of Dual-Phase Steel

Singh, M P and Das, Avimanyu and Venugopalan, T and Mukherjee, K and Walunj, Mahesh and Nanda, T and Kumar, B Ravi (2018) Impact of Martensite Spatial Distribution on Quasi-Static and Dynamic Deformation Behavior of Dual-Phase Steel. Metallurgical and Materials Transactions A:Physical Metallurgy and Materials Science, 49A(2) (IF-1.887). pp. 463-475.

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Abstract

The effects of microstructure parameters of dual-phase steels on tensile high strain dynamic deformation characteristic were examined in this study. Cold-rolled steel sheets were annealed using three different annealing process parameters to obtain three different dual-phase microstructures of varied ferrite and martensite phase fraction. The volume fraction of martensite obtained in two of the steels was near identical (similar to 19 pct) with a subtle difference in its spatial distribution. In the first microstructure variant, martensite was mostly found to be situated at ferrite grain boundaries and in the second variant, in addition to at grain boundaries, in-grain martensite was also observed. The third microstructure was very different from the above two with respect to martensite volume fraction (similar to 67 pct) and its morphology. In this case, martensite packets were surrounded by a three-dimensional ferrite network giving an appearance of core and shell type microstructure. All the three steels were tensile deformed at strain rates ranging from 2.7 x 10(-4) (quasi-static) to 650 s(-1) (dynamic range). Field-emission scanning electron microscope was used to characterize the starting as well as post-tensile deformed microstructures. Dual-phase steel consisting of small martensite volume fraction (similar to 19 pct), irrespective of its spatial distribution, demonstrated high strain rate sensitivity and on the other hand, steel with large martensite volume fraction (similar to 67 pct) displayed a very little strain rate sensitivity. Interestingly, total elongation was found to increase with increasing strain rate in the dynamic regime for steel with core-shell type of microstructure containing large martensite volume fraction. The observed enhancement in plasticity in dynamic regime was attributed to adiabatic heating of specimen. To understand the evolving damage mechanism, the fracture surface and the vicinity of fracture ends were studied in all the three dual-phase steels.

Item Type:Article
Official URL/DOI:http://10.1007/s11661-017-4433-y
Uncontrolled Keywords:Strain-hardening behavior; trip strip steels; volume fraction; mechanical-properties; tensile properties; morphology; microstructure; sheets; rates; size
Divisions:Metal Extraction and Forming
ID Code:7828
Deposited By:Sahu A K
Deposited On:22 Jun 2018 17:22
Last Modified:26 Jul 2018 09:41
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