scholarly journals Prediction on the Mechanical and Forming Behaviors of Ferrite-Martensite Dual Phase Steels Based on a Flow Model

2020 ◽  
Vol 26 (4) ◽  
pp. 401-407
Author(s):  
Rui-bin GOU ◽  
Wen-jiao DAN ◽  
Wei-gang ZHANG ◽  
Min YU
Keyword(s):  
Flow Model ◽  
Yield Function ◽  
Dual Phase ◽  
Cylindrical Bending ◽  
Dual Phase Steels ◽  
Martensite Content ◽  
Hardening Law ◽  
Anisotropic Yield Function ◽  
Micro Flow ◽  
Incremental Strain

An innovative flow model incorporating the mixture hardening law, anisotropic yield function, and incremental strain formulations was elaborated and applied to DP590 ferrite-martensite dual phase steel. To verify the flow model, both the macro/micro stress-strain responses and the forming patterns of DP590 steel with different martentite contents were simulated during the processes of the cup deep-drawing and the unconstrained cylindrical bending to evaluate the influence of martensite content on the mechanical and forming behavior of the steel. It was found that maternsite content has a significant impact on the macro/micromechanical and forming behavior of the steel, i.e., the ferrite and steel effective stresses and the effective macro/micro-strain distribution in the cup. Under the unconstrained cylindrical bending, the simulated effective maximum macro/micro-strains were in good agreement with the calculated results from the mixture law-based model. It was concluded that the Buaschinger effect is the main reason for an 8 % error between the simulated and experimental results. The flow model was proved to predict the macro/micro flow and forming behavior of the dual phase steels with a good accuracy.

Effects of Elastic Modulus Degradation on Simulation of Stretch-Bend Springback of Dual Phase Steel

2011 ◽  
Vol 299-300 ◽  
pp. 260-264
Author(s):  
Chao Lu ◽  
Yong Lin Kang ◽  
Guo Ming Zhu ◽  
Ren Dong Liu ◽  
Li Lin
Keyword(s):  
Elastic Modulus ◽  
Dual Phase Steel ◽  
Yield Function ◽  
Isotropic Hardening ◽  
Dual Phase ◽  
Hardening Law ◽  
Stretch Bending ◽  
Anisotropic Yield Function ◽  
Elastic Modulus Degradation ◽  
Springback Prediction

The stretch-bend springback of dual phase steel DP590 was studied experimentally and numerically in this paper. The aim of this work is to investigate the effects of elastic modulus degradation on springback prediction. Two anisotropic yield function yld89 and yld2000 were utilized along with isotropic hardening law. The appropriate material parameters characterizing the elastic modulus decrease were identified by response surface modeling. The current work showed that the accuracy of springback simulation improved when considering elastic modulus decreased with plastic strain and yld2000 can predict springback more accurately considering blank orientation in stretch bending.

Limit Strains Analysis of Advanced High Strength Steels Sheets Based on Surface Roughness Measurements

2018 ◽  
Vol 930 ◽  
pp. 349-355
Author(s):  
Lílian Barros da Silveira ◽  
Luciano Pessanha Moreira ◽  
Ladario da Silva ◽  
Rafael Oliveira Santos ◽  
Fabiane Roberta Freitas da Silva ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Strength Steels ◽  
High Strength ◽  
Yield Function ◽  
Forming Limit ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Advanced High Strength Steels ◽  
Anisotropic Yield Function ◽  
Localization Model

The limit strains of dual-phase steels DP600 and 800 were evaluated in this work with a localization model formulated in plane-stress conditions using elasto-plastic constitutive equations. In this model, a geometrical imperfection parameter is defined from the sheet nominal thickness, initial ferrite grain size and average surface roughness. The proposed identification procedure provided a more physically meaning for this parameter and at best more conservative predictions in the drawing Forming Limit Curve (FLC) range of both investigated dual-phase steels. Nevertheless, the corresponding limit strains in the biaxial stretching region are underestimated with the present theoretical model. Thus, more detailed anisotropic yield function and hardening descriptions must be implemented to improve the accuracy of the FLC prediction of advanced high strength steels.

Strengthening and ductilization of laminate dual-phase steels with high martensite content

2021 ◽  
Vol 65 ◽  
pp. 29-37
Author(s):  
Bo Gao ◽  
Rong Hu ◽  
Zhiyi Pan ◽  
Xuefei Chen ◽  
Yi Liu ◽  
...  
Keyword(s):  
Dual Phase ◽  
Dual Phase Steels ◽  
Martensite Content

scholarly journals Estimation of Strength Properties from Microhardness Results in Dual Phase Steels with Different Martensite Volume Fraction

2018 ◽  
Vol 47 (3) ◽  
pp. 206-212 ◽  
Author(s):  
Gábor Béres ◽  
Zoltán Weltsch
Keyword(s):  
Volume Fraction ◽  
Tensile Tests ◽  
Strength Properties ◽  
Indentation Load ◽  
Experimental Investigations ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Martensite Volume Fraction ◽  
Martensite Content ◽  
Hardness Values

This study is about the effect of the martensite volume fraction and indentation load on microhardness profiles of dissimilar types Dual Phase steels and DC04 mild steel. Experimental investigations were performed by mickrovickers method with using of eight different indentation loads from 0.01 kp up to 1 kp. Besides, microscope and tensile tests were carried out to complete the estimation.The hardness profiles show similar characteristics in case of all examined steels independent from the microstructure. In the lowest load ranges at 0.01 and 0.025 kp (HV0.01 and HV0.025), there are no appropriate approximations with the martensite volume fraction, due to the high deviation of the hardness results which caused by the little indentation geometry. In higher ranges, above 0.05 kp (HV0.05), linear evaluations could be applicable. With the utilization of the fitted parameters, a definite relationship is reported in the hardness values and even in the strength and elongation properties with the martensite content. Based on these correlations such contexts are added which make contact between microhardness and strength values for the practice. The discrepancy between the measured and calculated results stay under 10 HV which is less than 5%.

scholarly journals Experimental Investigation and Plasticity Modeling of SS316L Microtubes Under Varying Deformation Paths

2020 ◽  
Author(s):  
Elizabeth Mamros ◽  
Jinjin Ha ◽  
Yannis Korkolis ◽  
Brad Kinsey
Keyword(s):  
Axial Loading ◽  
Material Model ◽  
Yield Function ◽  
Biaxial Stress ◽  
Loading Path ◽  
Hardening Law ◽  
Anisotropic Yield Function ◽  
Final Stress ◽  
Strain Paths ◽  
Stress States

Abstract In this paper, results for SS316L microtube experiments under combined inflation and axial loading for single and multi-loading segment deformation paths are presented along with a plasticity model to predict the associated stress and strain paths. The microtube inflation/tension machine, utilized for these experiments, creates biaxial stress states by applying axial tension or compression and internal pressure simultaneously. Two types of loading paths are considered in this paper, proportional (where a single loading path with a given axial:hoop stress ratio is followed) and corner (where an initial pure loading segment, i.e., axial or hoop, is followed by a secondary loading segment in the transverse direction, i.e., either hoop or axial, respectively). The experiments are designed to produce the same final strain state under different deformation paths, resulting in different final stress states. This difference in stress state can affect the material properties of the final part, which can be varied for the intended application, e.g., biomedical hardware, while maintaining the desired geometry. The experiments are replicated in a reasonable way by a material model that combines the Hill 1948 anisotropic yield function and the Hockett-Sherby hardening law. Discussion of the grain size effects during microforming impacting the ability to achieve consistent deformation path results is included.

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