Effect of ferrite-martensite interface morphology on bake hardening response of DP590 steel

Chakraborty, A and Adhikary, M and Venugopalan, T and Nanda, T and Kumar, B R (2016) Effect of ferrite-martensite interface morphology on bake hardening response of DP590 steel. Materials Science and Engineering A-Structural Materials Properties Micro structure and Processing, 676 (IF-3.094). pp. 463-473.

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The effect of martensite spatial distribution and its interface morphology on the bake hardening characteristics of a dual phase steel was investigated. In one case, typical industrial continuous annealing line parameters were employed to anneal a 67% cold rolled steel to obtain a dual phase microstructure. In the other case, a modified annealing process with changed initial heating rates and peak annealing temperature was employed. The processed specimens were further tensile pre-strained within 1-5% strain range followed by a bake hardening treatment at 170 degrees C for 20 min. It was observed that industrial continuous annealing line processed specimen showed a peak of about 70 MPa in bake-hardening index at 2% pre-strain level. At higher pre-strain values a gradual drop in bake-hardening index was observed. On the contrary, modified annealing process showed near uniform bake-hardening response at all pre-strain levels and a decrease could be noted only above 4% pre-strain. The evolving microstructure at each stage of annealing process and after bake-hardening treatment was studied using field emission scanning electron microscope. The microstructure analysis distinctly revealed differences in martensite spatial distribution and interface morphologies between each annealing processes employed. The modified process showed predominant formation of martensite within the ferrite grains with serrated lath martensite interfaces. This nature of the martensite was considered responsible for the observed improvement in the bake-hardening response. Furthermore, along with improved bake-hardening response negligible loss in tensile ductility was also noted. This behaviour was correlated with delayed micro-crack initiation at martensite interface due to serrated nature. (C) 2016 Elsevier B.V. All rights reserved.

Item Type:Article
Official URL/DOI:https://www.researchgate.net/publication/307998549...
Uncontrolled Keywords:Dual phase steel; Bake-hardening; Martensite; Pre-strain; Ferrite/martensite interface
Divisions:Metal Extraction and Forming
ID Code:7524
Deposited By:Sahu A K
Deposited On:14 Aug 2017 13:40
Last Modified:15 Sep 2017 12:01
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