Impact of Strain Rate on Microalloyed Steel Sheet Breaking (original) (raw)
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The Effect of Strain Rate on the Mechanical Properties of Automotive Steel Sheets
Acta Polytechnica, 2013
The automotive industry is currently seeking detailed information about various types of materials and their behavior under dynamic loading. Dynamic tensile testing of sheet steels is growing in importance. The experimental dynamic tensile technique depends on the strain rate. Each type oftest serves for a specific range of strain rates, and provides specific types of information. This workdeals with the influence of the strain rate on the mechanical properties of automotive steel sheets.Three different types of steel: IF steel, DP steel, and micro-alloyed steel (S 460) were used to compare static and dynamic properties.
Analysis of the Influence of the Loading Rate on the Mechanical Properties of Microalloyed Steel
The aim of this paper is to analyse the influence of the loading rate in the range from 1 to 1000 mm/min, which corresponds to the tensile machine working range, on the strength properties and the formability characteristics obtained on standard and notched test bars made of steel strips. The combination of the loading rate and the test bar type made it possible to obtain the relationship of monitored variables in the strain rate interval from 10 -4 to 10 s -1 . In this interval, the strength properties of the tested strips thickness of 1, 1.5 and 1.8 mm increase exponentially, but formability does not change up to the strain rate of 1 s -1 .
Dynamic characteristics of automotive steel sheets
Metalurgija, 2016
M. Mihaliková, A. Lišková, Faculty of Metallurgy, Technical University of Košice, Slovakia The aim of this experimental research was to perform an analysis of deformation characteristics on two different types of steel: IF steel, and micro-alloyed steel were used automotive industry. For that purpose changes of properties of these materials were carried out by static 10-3 · s-1 and dynamic 103 · s-1 strain rate assess its plastic properties. Vickers micro hardness test was carried out by the static and dynamic loading condition and describes different hardness distribution. The higher strain hardening of materials was obtained too that was confirmed by distribution of dislocations.
The Analysis of Automotive Steels at different Strain Rate
Materials Today: Proceedings, 2016
Currently, the automotive industry uses sheets of different qualities. The most common ones include IF (Interstitial Free) steel and micro-alloyed steel. Use of quality sheet depends on the point of application in car production. Testing and product testing is a standard part of the process of innovation and production itself. Testing of automotive steels under dynamic conditions is increasingly important. Changing the hardness HV 1 was performed on the fractured bars under static and dynamic loading conditions. Tests were made on steel IF and S 460.
SAE technical paper series, 2009
The effect of oscillatory shear during heat-induced gelation of whey protein isolate has been investigated. For each gel sample, a single oscillating strain was applied during the gelation process from within the range of 0-1.0. A strain sweep was then used to evaluate the linear viscoelastic region as well as the fracturing properties of each gel. The application of strains lower than~0.01 during gelation did not affect the storage modulus while larger strains resulted in lower storage moduli in the linear viscoelastic region. Furthermore, gels produced under small (<0.01) strain amplitudes showed a single fracture point, while gels produced under high (>0.01) amplitude strain were characterised by a two-step fracture pattern. Between the fracture steps, strain hardening behaviour was observed. Confocal laser scanning microscopy was used to identify structural differences between the gels. Greater inhomogeneity was found in gels produced under large amplitude compared to small amplitude strain. It is suggested that localised redistribution of aggregates due to shear during gelation increases the average pore size and possibly creates two distinct types of aggregate structure with differing moduli. The combined effect of heating rate and oscillatory strain was also investigated. We postulate that the mechanism underlying our observations is generic to many gel systems.
Microalloyed Steel Under Tension and Bending Condition
The article deals with the influence of the loading rate in the interval from 1 to 1000 mm/min on the mechanical properties of drawing steel sheet, used for the manufacture of automotive parts, under tension and bending conditions. It describes the aspects of material characteristics under tension and bending conditions, while bending tests were made on notched specimens (a modified impact bending test). With an increasing strain rate up to the critical value, the resistance of material against strain increases and hence the yield point and the tensile strength increase, the deformation ability, the deformation homogeneity, the structure and the substructure after deformation, etc. are changed. The paper presents knowledge that using a modified notch toughness test it is possible to achieve the formability characteristics corresponding to dynamic strain rates even under the static loading.
Microstructural development during mechanical forming of steel sheets
2013
Abstract — Metal forming is used synonymously with deformation, a process during which an object gets changed due to the applied force. These changes can either be reversible or irreversible depending on the type of material; size and geometry of the object and the magnitude of the applied force to the object. This paper reports the microstructural development after mechanical forming of steel sheet material by varying the applied loads. The microstructural evaluations showed that the applied loads employed caused an increase in the magnitude of the grain sizes in each loaded specimen. Furthermore, the increase in the grain size of the microstructure was observed to be directly proportional to the loads applied. In addition, the microhardness values of the cross sections investigated were found to increase with the applied loads. Hence, the grain size growth and the hardness were linearly dependent on the applied loads, and this implies that there is a correlation between the appl...
Journal of Materials Engineering and Performance, 2018
In order to ensure crash resistance of the steels used in automotive components, the ensile deformation behavior needs to be studied and predicted not only under quasi-static condition, but also under dynamic loading rates. In the present study, tensile tests have been performed on four different automobile grade sheet steels, namely interstitial free steel, dual-phase 600 and 800, and a carbon manganese steel over the strain rate regime of 0.001-800/s. Apart from the variation in strength (which always increased with strain rate), the effect of strengthening mechanism on strain rate sensitivity and strain hardening behavior has been evaluated. Strain rate sensitivity was found to increase at high-strain rate regime for all the steels. Contribution of solid solution hardening on strain rate sensitivity at lower plastic strains was found to be higher compared to dislocation strengthening and second-phase hardening. However, precipitation hardening coupled with solid solution hardening produced the highest strain rate sensitivity, in C-Mn-440 steel at high strain rates. Different strain-rate-sensitive models which take into account the change in yield stress and strain hardening behavior with strain rate for ductile materials were used to predict the flow behavior of these sheet steels at strain rates up to 800/s.
1990
The liver is one of the most frequently injured organs in abdominal trauma. Although motor vehicle collisions are the most common cause of liver injuries, current anthropomorphic test devices are not equipped to predict the risk of sustaining abdominal organ injuries. Consequently, researchers rely on finite element models to assess the potential risk of injury to abdominal organs such as the liver. These models must be validated based on appropriate biomechanical data in order to accurately assess injury risk. This study presents a total of 36 uniaxial unconfined compression tests performed on fresh human liver parenchyma within 48 h of death. Fach specimen was tested once to failure at one of four loading rates (0.012, 0.106, 1.036, and 10.708s'') in order to investigate the effects of loading rate on the compressive failure properties of human liver parenchyma. The results of this study showed that the response of human liver parenchyma is both nonlinear and rate dependent. Specifically, failure stress significantly increased with increased loading rate, while failure strain significantly decreased with increased loading rate. The failure stress and failure strain for all liver parenchyma specimens ranged from-38.9 kPa to-145.9kPa and from-0.48 strain to-1.15 strain, respectively. Overall, this study provides novel biomechanical data that can be used in the development of rate dependent material models and the identification of tissue-level tolerance values, which are critical to the validation of finite element models used to assess injury risk.
High Strength Hot Rolled Steel Sheet for Automobile – A Review
Large weight reduction by application of high strength steels to underbody parts can be expected since relatively thick sheets are now adopted. In several different approaches to improve press formability of high strength hot rolled steels are explained. The basic concept of mechanical property control and the performances of a couple of high strength hot rolled steels. The fatigue strength of the steel sheet with scale increases with the decrease in the roughness of the steel sheet surface. The fatigue strength of the sheared edge deteriorates with the increase in the fractured plane roughness of the sheared edge. In case of the microstructure consisting of pearlite and coarse carbides, these phases increase the fractured plane roughness through the connection of the micro-voids arising around them. Accordingly, the reduction of these phases is significant for improving the fatigue strength. Based on these findings, three types of the 780MPa grade high strength hot rolled steel sheet for truck frame use have been developed.