A Comparative Evaluation of Third-Generation Advanced High-Strength Steels for Automotive Forming and Crash Applications

Noder, Jacqueline; Gutierrez, Jon Edward; Zhumagulov, Amir; Dykeman, James; Ezzat, H. A.; Butcher, Cliff

doi:10.3390/ma14174970

Cited by 14 publications

(7 citation statements)

References 57 publications

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“…Therefore, formability and crashworthiness must be characterized with more accurate methods, such as forming limit diagrams and assessments of fracture locus. [24,25] Further studies of the influence of strain rate on formability and crashworthiness are thus necessary. Moreover, to clarify the observed mechanism behind the work-hardening anomaly, more detailed TEM investigations should be conducted.…”

Section: Resultsmentioning

confidence: 99%

Abnormal Strain Rate‐Dependent Work‐Hardening Behavior in Quenching and Partitioning Steel

Bisch,

Fang

2024

steel research int.

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Due to their high levels of formability and crashworthiness, the new quenching and partitioning (QP) steels are increasingly being used in car‐body structures. Using a unique experimental technique for tensile testing in a large strain‐rate range of 10−4–1000 s−1, an anomalous work‐hardening behavior is found in a QP1180 steel that may affect its formability and crashworthiness. At the lowest strain rate of 10−4 s−1, the work‐hardening rate θ decreases linearly with increasing flow stress. With an increasing strain rate, however, an increasingly severe nonlinearity in the work‐hardening rate is evident, as has been observed in metastable austenitic steels when the deformation‐induced martensitic transformation occurs at lower temperatures. This work‐hardening‐rate peak reaches its maximum at 10 s−1. Above this value, the peak decreases again, and at more than 500 s−1, it behaves like the quasi‐static test. The corresponding material characteristics, such as elongation and strength, change similarly.

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Section: Resultsmentioning

confidence: 99%

Abnormal Strain Rate‐Dependent Work‐Hardening Behavior in Quenching and Partitioning Steel

Bisch,

Fang

2024

steel research int.

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“…The tests were conducted without any lubricant to be in line with the elevated temperature cases. Details regarding the tooling, test setup and data acquisition are discussed in Noder et al [10]. A minimum of five repeats were conducted for each test condition.…”

Section: Conical Hole Expansion At Room and Elevated Temperaturesmentioning

confidence: 99%

“…The HER represents deformation under a non-linear strain path due to the initial compression of the inner hole edge when in contact with the conical punch before gradually transitioning to uniaxial tension [12]. Conversely, the outer hole edge remains in a uniaxial tensile stress state throughout the test and is utilized to determine the fracture strain from the initial and final diameters [10,12]. The average major and equivalent strain in terms of the average outer diameter at fracture (…”

Section: Conical Hole Expansion At Room and Elevated Temperaturesmentioning

confidence: 99%

Sheared Edge Formability Characterization of High Strength Aluminum Alloys at Room and Elevated Temperatures using Hole Expansion Tests

Narayanan

George

Cheong

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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High strength 6000- and 7000-series aluminum alloys have significant potential for automotive light weighting due to their high strength-to-weight ratios. Alternate thermal processing routes and warm forming operations with rapid heating to 150 - 300°C are being explored to expand their forming process windows. While the constitutive and formability behavior of these alloys at elevated temperatures is an active area of research, limited data is available on their sheared edge stretchability, particularly under elevated temperature forming conditions. To this end, the influence of cutting clearance on the edge fracture limits of two precipitation hardening alloys, AA6013-T4 and AA7075-T6, and a non-heat treatable AA5182-O were first investigated at room temperature using the conical hole expansion test. A 12% clearance was found to be suitable for the three materials and used to process the hole expansion samples prior to warm forming. Microhardness tests were used to characterize the depth and severity of the shear affected zone (SAZ) for the AA7075-T6 before and after the warm forming cycle. The forming temperature was found to increase the hole expansion ratio by approximately 400%, 150%, and 520% for the AA5182-O, AA6013-T4, and AA7075-T6 respectively relative to the room temperature tests. The edge stretchability during W-temper forming of the AA6013 and AA7075 at room temperature was also assessed. It was observed that W-temper forming negatively influenced the hole expansion of AA6013 by approximately 30% relative to the T4 condition. Conversely, the hole expansion ratio for AA7075 when formed in W-temper increased by over 35% with respect to the T6 temper.

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“…Finite element analysis (FEA) was employed to validate the stress state within the coupons. Subsequently, the numerical results obtained from the FEA were compared to the experimental data acquired through digital image correlation (DIC) strain measurement [8,[33][34][35][36]. The proportional fracture locus of the DP1180 steel was then calibrated and lengthscale effects of the finite-elements model and DIC discussed.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Fracture Characterization of DP1180 Steel in Combined Simple Shear and Uniaxial Tension

Khameneh

Abedini

Butcher

2023

Metals

Self Cite

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Current tests for plane stress characterization of fracture in automotive sheet metals include simple shear, uniaxial, plane strain, and biaxial tension, but there is a significant gap between shear and uniaxial tension. Presently, it remains uncertain whether the fracture strain experiences a reduction between simple shear and uniaxial tension or undergoes an exponential increase as the triaxiality decreases. Fracture in combined simple shear and tension is complicated by premature edge cracking in tension along with a strong sensitivity of fracture strain to the measurement lengthscale. To address these issues, several existing simple shear geometries were modified and evaluated, with a focus on obtaining approximately linear strain paths corresponding to combined uniaxial tension and simple shear suitable for experimental fracture characterization using digital image correlation (DIC). An experimental and numerical investigation was conducted using two planar geometries that do not require through-thickness machining and can be easily tested on a universal test frame. Finite-element analysis was used to investigate the influence of the notch eccentricity on the stress state and predicted fracture location. The most promising geometry in each coupon type was then selected and tested for a dual-phase advanced high-strength steel, DP1180. The performance of the two planar geometries was evaluated based on the linearity of strain and stress state, along with the location of fracture initiation. The best geometry was then used to evaluate and recalibrate the modified Mohr-Coulomb (MMC) fracture locus with data in combined shear and tension. The initial MMC calibration using four fracture tests that suppressed necking provided an accurate estimate for the fracture strain in combined uniaxial tension and simple shear. The MMC model correctly predicted a valley in the fracture strain between these two loading conditions.

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A Comparative Evaluation of Third-Generation Advanced High-Strength Steels for Automotive Forming and Crash Applications

Cited by 14 publications

References 57 publications

Abnormal Strain Rate‐Dependent Work‐Hardening Behavior in Quenching and Partitioning Steel

Abnormal Strain Rate‐Dependent Work‐Hardening Behavior in Quenching and Partitioning Steel

Sheared Edge Formability Characterization of High Strength Aluminum Alloys at Room and Elevated Temperatures using Hole Expansion Tests

Experimental and Numerical Fracture Characterization of DP1180 Steel in Combined Simple Shear and Uniaxial Tension

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