Review of the Shearing Process for Sheet Steels and Its Effect on Sheared-Edge Stretching

Lévy, Bernard; Tyne, C. J. Van

doi:10.1007/s11665-011-9997-x

Cited by 63 publications

(34 citation statements)

References 6 publications

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“…15) Stretch-flangeability of sheared edges is usually evaluated by hole expansion testing on punched holes. 16) The hole expansion ratio (HER) of multiphase steel grades strongly depends on the strength ratio between the different microstructure constituents [17][18][19][20][21][22] and on their geometrical arrangement. 17,20) The possible presence of retained austenite, depending on whether it has transformed or not during the punching prior to the hole expansion test, may also affect the hole expansion ratio.…”

Section: On the Effect Of Qandp Processing On The Stretch-flange-formabmentioning

confidence: 99%

On the Effect of Q&P Processing on the Stretch-flange-formability of 0.2C Ultra-high Strength Steel Sheets

et al. 2018

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Quenching and Partitioning (Q&P) has been proposed as a novel heat treatment to produce cold rolled sheets with excellent strength and sufficient formability for cold stamping. The impact of Q&P processing on microstructure and tensile properties has been extensively studied in contrast to the lower attention devoted to its effect on stretch-flange-formability. In this study, the stretch-flange-formability of Q&P microstructures is investigated by means of hole expansion tests carried out on punched holes. The balance between tensile properties and hole expansion ratios (HER) is discussed and compared to three model microstructures: biphasic dual-phase (DP), single phase quenched & tempered (Q&T) and quenched & austempered (QAT). It is shown that Q&P microstructures exhibit a better combination of tensile ductility and stretch-flange-formability than fully martensitic (excellent HER but poor tensile ductility) and austempered microstructures (good ductility but poor HER). The study of the impact of the Q&P parameters demonstrates that stretch-flange-formability is further promoted by choosing low quench temperatures and long partitioning times. The hole expansion properties are linked to the hardness gradients in the microstructure, evaluated by nanohardness mapping. The narrower nanohardness distribution in the Q&P microstructure leads to better hole expansion ratios compared to bainitic microstructures obtained by austempering, where the presence of hard M/A blocks is unavoidable.

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Section: On the Effect Of Qandp Processing On The Stretch-flange-formabmentioning

confidence: 99%

On the Effect of Q&P Processing on the Stretch-flange-formability of 0.2C Ultra-high Strength Steel Sheets

et al. 2018

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“…The shearing process introduces two zones; a shear face (sheared edge) and a zone of deformation behind the shear face known as the shear-affected zone (SAZ) [ 8 ]. The shear face is comprised of four zones: roll-over, burnish, fracture, and shear-burr [ 8 ]. The SAZ is characterized by severe work-hardening and damage in the form of pre-nucleated voids formed during the shearing process.…”

Section: Introductionmentioning

confidence: 99%

“…In the automotive industry, holes are generally sheared because it is more economical and faster than machining operations. However, the presence of the SAZ reduces the formability of the sheared edge [ 8 , 9 , 10 , 11 ]. Since the features of the sheared edge are formed as a result of deformation and fracture within the material, the sensitivity to the shearing process during subsequent edge stretching is strongly dependent upon the microstructure.…”

Section: Introductionmentioning

confidence: 99%

Damage Evolution in Complex-Phase and Dual-Phase Steels during Edge Stretching

et al. 2017

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The role of microstructural damage in controlling the edge stretchability of Complex-Phase (CP) and Dual-Phase (DP) steels was evaluated using hole tension experiments. The experiments considered a tensile specimen with a hole at the center of specimen that is either sheared (sheared edge condition) or drilled and then reamed (reamed edge condition). The damage mechanism and accumulation in the CP and DP steels were systematically characterized by interrupting the hole tension tests at different strain levels using scanning electron microscope (SEM) analysis and optical microscopy. Martensite cracking and decohesion of ferrite-martensite interfaces are the dominant nucleation mechanisms in the DP780. The primary source of void nucleation in the CP800 is nucleation at TiN particles, with secondary void formation at martensite/bainite interfaces near the failure strain. The rate of damage evolution is considerably higher for the sheared edge in contrast with the reamed edge since the shearing process alters the microstructure in the shear affected zone (SAZ) by introducing work-hardening and initial damage behind the sheared edge. The CP microstructures were shown to be less prone to shear-induced damage than the DP materials resulting in much higher sheared edge formability. Microstructural damage in the CP and DP steels was characterized to understand the interaction between microstructure, damage evolution and edge formability during edge stretching. An analytical model for void evolution and coalescence was developed and applied to predict the damage rate in these rather diverse microstructures.

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“…Wide investigation of HER has established that the HER depends on several parameters: mechanical properties of sheet material (Ref 5,6), the surface quality of the initial hole edge or fabrication process of hole (Ref 7,8) Karelova et al (Ref 13) found that complex-phase steel grade (CP800) has higher HER than dual-phase (DP) steel grade (DP800) for identical hole edge conditions, even though the elongation properties determined in uniaxial tensile tests show the opposite tendency. They also found that induced plastic deformation and surface quality obtained by the hole preparation method significantly affect the hole expansion behavior.…”

Section: Introductionmentioning

confidence: 99%

Non-linear Correlation Between Uniaxial Tensile Properties and Shear-Edge Hole Expansion Ratio

Paul

2014

J. of Materi Eng and Perform

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Stretch flanging of steel sheets is an important formability issue for automobile industry. Finite element simulation study confirms that the edge of the hole deforms in a uniaxial tensile manner during the hole expansion process. To understand the effect of various tensile properties on hole expansion ratio, current experimental data and collected data from published work have been used. Yield stress, ultimate tensile stress, coefficient of normal anisotropy, total elongation, and post uniform elongation are closely related to hole expansion ratio. A non-linear relationship between hole expansion ratio and tensile properties (ultimate tensile stress, coefficient of normal anisotropy, and total elongation) is developed in the present investigation.

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Review of the Shearing Process for Sheet Steels and Its Effect on Sheared-Edge Stretching

Cited by 63 publications

References 6 publications

On the Effect of Q&P Processing on the Stretch-flange-formability of 0.2C Ultra-high Strength Steel Sheets

On the Effect of Q&P Processing on the Stretch-flange-formability of 0.2C Ultra-high Strength Steel Sheets

Damage Evolution in Complex-Phase and Dual-Phase Steels during Edge Stretching

Non-linear Correlation Between Uniaxial Tensile Properties and Shear-Edge Hole Expansion Ratio

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