Effect of martensite volume fraction on abnormal work hardening behavior of a low carbon low alloy ferrite–martensite dual-phase steel

Abstract

This paper investigates the work hardening behavior of a low carbon low alloy steel under various ferrite-martensite dual-phase (DP) microstructures. For this purpose, several DP microstructures containing 23- 87% martensite volume fraction (MVF) were developed by application of inter-critical annealing heat treatment processes. The Hollomon analysis was employed in conjunction with mechanical testing and electron microscopy observation to describe the work hardening behavior of DP samples. The experimental results indicated that the DP specimens containing lower than 36% MVF were associated with a ‘single stage’ of work hardening behavior while those of higher than 36% of martensitic microconstituents were related to a ‘double stage’ of work hardening pattern. With increasing the MVF from 23 to 87%, the strain hardening exponent for the first stage of work hardening showed a peak value of 0.111 at MVF = 73%, while those for the second stage of strain hardening exponents were continuously increased from 0.162 to 0.197. This abnormal trend of strain hardening exponents with MVF was correlated with the variable hardening responses of ferrite and martensite microconstituents.

Tensile behavior of martensite + ferrite micro-layered 15CrMo steel plates

“…In recent years, the excellent performance of dual-phase steels has gradually been concerned by researchers [1][2][3][4][5]. In a typical martensite(M) + ferrite(F) dual-phase steel, the hard phase is martensite whose high hardness and strength can improve the strength of the whole material; the soft phase is ferrite whose excellent tensile plasticity can improve the plasticity of the whole material [6][7][8][9]. References of [10][11][12][13] believe that the layer structure with combinations of high strength and high ductility can be obtained by regulating the size and volume fraction ratio of the hard and soft phase layers, is the nearly ideal heterogeneous material model.…”

Strain-Hardening Prediction of DP600 Steel Considering the Heterogeneous Deformation Between Ferrite and Martensite

“…The high martensitic volume fraction in DP steel can significantly improve the strength and subsequently reduce the elongation [13,14]. The local topography [15], stress triaxiality [16] and strain partition [17] of martensite affect the work hardening stage [18], damage and crack behaviors [19], cycle fatigue life [20] and formability [21].…”