scholarly journals New Insights into the Microstructural Changes During the Processing of Dual-Phase Steels from Multiresolution Spherical Indentation Stress–Strain Protocols

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 18 ◽  
Author(s):  
Ali Khosravani ◽  
Charles M. Caliendo ◽  
Surya R. Kalidindi
Keyword(s):  
Cold Work ◽  
Martensite Phase ◽  
Spherical Indentation ◽  
Dual Phase ◽  
Bake Hardening ◽  
Stress Strain ◽  
Microstructural Changes ◽  
Mechanical Responses ◽  
Material Length ◽  
High Throughput Manner

In this study, recently established multiresolution spherical indentation stress–strain protocols have been employed to derive new insights into the microstructural changes that occur during the processing of dual-phase (DP) steels. This is accomplished by utilizing indenter tips of different radii such that the mechanical responses can be evaluated both at the macroscale (reflecting the bulk properties of the sample) and at the microscale (reflecting the properties of the constituent phases). More specifically, nine different thermo-mechanical processing conditions involving different combinations of intercritical annealing temperatures and bake hardening after different amounts of cold work were studied. In addition to demonstrating the tremendous benefits of the indentation protocols for evaluating the variations within each sample and between the samples at different material length scales in a high throughput manner, the measurements provided several new insights into the microstructural changes occurring in the alloys during their processing. In particular, the indentation measurements indicated that the strength of the martensite phase reduces by about 37% when quenched from 810 °C compared to being quenched from 750 °C, while the strength of the ferrite phase remains about the same. In addition, during the 10% thickness reduction and bake hardening steps, the strength of the martensite phase shows a small decrease due to tempering, while the strength of the ferrite increases by about 50% by static aging.

scholarly journals Effects of Heterogeneous Microstructures on the Strain Hardening Behaviors of Ferrite-Martensite Dual Phase Steel

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 824 ◽  
Author(s):  
Chuang Ren ◽  
Wenjiao Dan ◽  
Yongsheng Xu ◽  
Weigang Zhang
Keyword(s):  
Flow Stress ◽  
Strain Hardening ◽  
Shape Factor ◽  
Grain Shape ◽  
Strain Curve ◽  
Martensite Phase ◽  
Dual Phase ◽  
Stress Strain ◽  
Dp Steel ◽  
Heterogeneous Microstructures

The complex strain hardening behaviors of dual phase (DP) steel are subjected to the heterogeneous microstructures. The current work aims to predict the strain hardening behaviors of ferrite-martensite DP steel, focusing on the effects of heterogeneous microstructure on mechanical properties. The flow stress of material was calculated based on the dislocation-based work-hardening model with considering the multi-boundaries hardening. The ferrite-martensite phase boundary percent and grain shape factor were selected as the heterogeneous feature parameters, which were introduced into the new proposed model. The theoretical calculated stress-strain responses were verified with experimental results using the tensile test. The model with the boundary strengthening consideration has more accurate results. The parameter effects of ferrite-ferrite boundary (FFB) spacing, ferrite-martensite boundary (FMB) percent, and grain shape factor on the flow stress-strain curve were researched.

MITTAL DI-FORM T700, HF80Y100T

Alloy Digest ◽  
2007 ◽  
Vol 56 (2) ◽  
Keyword(s):  
Automotive Industry ◽  
High Strength ◽  
Martensite Phase ◽  
Carbon Steels ◽  
Ferrite Phase ◽  
Dual Phase ◽  
Low Carbon ◽  
Advanced High Strength Steel ◽  
Dp Steels ◽  
Soft Ferrite

Abstract MITTAL DI-FORM T700 and HF80Y100T are low-carbon steels with a manganese and silicon composition. Dual-phase (DP) steels are one of the important advanced high-strength steel (AHSS) products developed for the automotive industry. Their microstructure typically consists of a soft ferrite phase with dispersed islands of a hard martensite phase. The martensite phase is substantially stronger than the ferrite phase. The DI-FORM grades exhibit low yield-to-tensile strengths, and the numeric designation in the name corresponds to the tensile strength. This datasheet provides information on microstructure and tensile properties as well as deformation and fatigue. It also includes information on forming. Filing Code: SA-561. Producer or source: Mittal Steel USA Flat Products.

MITTAL DI-FORM T590, T600

Alloy Digest ◽  
2007 ◽  
Vol 56 (1) ◽  
Keyword(s):  
Tensile Strength ◽  
Automotive Industry ◽  
High Strength ◽  
Martensite Phase ◽  
Ferrite Phase ◽  
Dual Phase ◽  
Bend Strength ◽  
Low Carbon ◽  
Advanced High Strength Steel ◽  
Soft Ferrite

Abstract MITTAL DI-FORM T590 and T600 are low-carbon dual-phase steels containing manganese and silicon. Dual-phase (DP) steels are important advanced high-strength steel (AHSS) products developed for the automotive industry. Their microstructure typically consists of a soft ferrite phase with dispersed islands of a hard martensite phase. The martensite phase is substantially stronger than the ferrite phase. The DI-FORM grades exhibit low yield-to-tensile strength ratios. The numeric designation in the grade name corresponds to the tensile strength in MPa. This datasheet provides information on microstructure, tensile properties, and bend strength as well as fatigue. It also includes information on forming. Filing Code: SA-558. Producer or source: Mittal Steel USA Flat Products.

Predicting Plastic Flow Behaviour, Failure Mechanisms and Severe Deformation Localisation of Dual-Phase Steel using RVE Simulation

2021 ◽  
Vol 18 (1) ◽  
pp. 8601-8611
Author(s):  
A. K. Rana ◽  
P. P. Dey
Keyword(s):  
Plastic Strain ◽  
Failure Modes ◽  
Volume Fraction ◽  
Ferrite Matrix ◽  
Martensite Phase ◽  
Von Mises Stress ◽  
Dual Phase ◽  
Strain Partitioning ◽  
Deformation Inhomogeneity ◽  
Von Mises

In this work, the von Mises stress and plastic strain distribution of Ferrite-Martensite–Dual-Phase (FMDP) steels are predicted at various stages of deformation. The failure modes and volume fraction effect are identified based on Representative Volume Element (RVE). FMDP steel consists of a typical ferrite-matrix phase, in which martensite-islands are dispersed. Recently FMDP steels are increasingly used to the various car parts in demand. 2D-RVEs are also utilised to predict the orientations effect of the martensite phase in the FMDP steels. Based on the position of the element, the boundary conditions (BC) are given in the RVE of FMDP steel microstructures. The failure modes are examined in the form of severe plastic strain localisation. While the distribution of islands in the microstructure varies, as a result, the deformation inhomogeneity increases with a rise of martensite fraction. The results of numerical computation and the trend of experimental failure shown in the literature are compared. This is signifying that the overall macro-behaviour of FMDP steel, as a consequence of stress-strain partitioning and influence of martensite-island volume fractions (MVFs), can be predicted by the finite element (FE) based 2D-RVE modelling.

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