Predicting Edge Cracks on Shear-Cut High-Strength Steels by Modified Uniaxial Tensile Tests

2016 ◽  
Vol 703 ◽  
pp. 49-55 ◽  
Author(s):  
Martin Feistle ◽  
Isabella Pätzold ◽  
Roland Golle ◽  
Wolfram Volk
Keyword(s):  
Tensile Test ◽  
Measurement Method ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Forming Process ◽  
Contact Measurement ◽  
Edge Cracks ◽  
Near Future

During the forming of high-strength steels, edge cracks occur unexpectedly on sheared edges e.g. during collar forming. A non-contact measurement method based on the well-known tensile test was developed. It allows the investigation of the formation of edge cracks under tensile loads and determining general criteria to predict the formation of edge cracks during a specific forming process. The criteria are validated experimentally by means of the collar-forming test. In conjunction with the proposed line-fit-method these criteria can be implemented easily in FEM software in the near future for the prediction of edge cracks.

scholarly journals The Evaluation of Laser Weldability of the Third-Generation Advanced High Strength Steel

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1051 ◽  
Author(s):  
António B. Pereira ◽  
Rafael O. Santos ◽  
Bruno S. Carvalho ◽  
Marilena C. Butuc ◽  
Gabriela Vincze ◽  
...  
Keyword(s):  
Automotive Industry ◽  
Greenhouse Gas Emission ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Weld Bead ◽  
Uniaxial Tensile ◽  
Third Generation ◽  
Advanced High Strength Steels

To meet the demands of vehicular safety and greenhouse gas emission reduction, the automotive industry is increasingly using advanced high strength steels (AHSS) in the production of the components. With the development of the new generation of AHSS, it is essential to study their behavior towards manufacturing processes used in the automotive industry. For this purpose, the welding capability of newly developed third-generation Gen3 980T steel was investigated using the Nd:YAG (Neodymium:Yittrium Aluminum Garnet) laser-welding with different parameter conditions. The analysis was made by uniaxial tensile tests, micro-hardness, Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The criteria used to evaluate the quality of the weld were the distance between the fracture and the weld bead and the surface finish. A relationship between the quality of the weld and the energy density was observed, expressed by a partial penetration for values below the optimal, and by irregularities in the weld bead and a high number of spatters for the values above the optimal.

Finite Element Modeling of Deformation Behavior of Steel Specimens under Various Loading Scenarios

2015 ◽  
Vol 651-653 ◽  
pp. 969-974 ◽  
Author(s):  
Dilip Banerjee ◽  
Mark Iadicola ◽  
Adam Creuziger ◽  
Tim Foecke
Keyword(s):  
Finite Element ◽  
Deformation Behavior ◽  
Stress Measurement ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Image Correlation ◽  
Uniaxial Tensile ◽  
Fe Model ◽  
Strain Paths

Lightweighting materials (e.g., advanced high strength steels, aluminum alloys etc.) are increasingly being used by automotive companies as sheet metal components. However, accurate material models are needed for wider adoption. These constitutive material data are often developed by applying biaxial strain paths with cross-shaped (cruciform) specimens. Optimizing the design of specimens is a major goal in which finite element (FE) analysis can play a major role. However, verification of FE models is necessary. Calibrating models against uniaxial tensile tests is a logical first step. In the present study, reliable stress-strain data up to failure are developed by using digital image correlation (DIC) technique for strain measurement and X-ray techniques and/or force data for stress measurement. Such data are used to model the deformation behavior in uniaxial and biaxial tensile specimens. Model predictions of strains and displacements are compared with experimental data. The role of imperfections on necking behavior in FE modeling results of uniaxial tests is discussed. Computed results of deformation, strain profile, and von Mises plastic strain agree with measured values along critical paths in the cruciform specimens. Such a calibrated FE model can be used to obtain an optimum cruciform specimen design.

Numerical Simulations and Experimental Results of Tensile Test Behavior of Laser Butt Welded DP980 Steels

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
S. K. Panda ◽  
N. Sreenivasan ◽  
M. L. Kuntz ◽  
Y. Zhou
Keyword(s):  
Tensile Test ◽  
Numerical Simulations ◽  
Tensile Testing ◽  
High Strength Steels ◽  
High Strength ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Vehicle Performance ◽  
Soft Zone ◽  
Uniaxial Tensile Testing

Laser welding of advanced high strength steels for fabrication of tailor welded blanks is of increasing interest for continued improvements in vehicle performance and safety without an increase in weight. Experimental results have shown that formability of welded dual-phase (DP) steels is significantly reduced by the formation of a softened region in the heat-affected zone (HAZ). In this study, a finite element simulation of welded DP980 samples undergoing transverse uniaxial tensile testing was used to evaluate the effects of soft zone width and strength on formability characteristics. Both the strength and the ductility of laser welded blanks decreased compared with those of unwelded blanks due to the formation of a softened outer-HAZ, where strain localization and final fracture occurred during tensile testing. The magnitude of softening and the width of the HAZ depend on the laser specific energy. It was observed from tensile test experiments and numerical simulations that both a decrease in strength and an increase in width of the softened HAZ were responsible for a decrease in the overall strength and ductility of the welded blanks.

scholarly journals Comprehensive Analysis of the Microstructure and Mechanical Properties of Friction-Stir-Welded Low-Carbon High-Strength Steels with Tensile Strengths Ranging from 590 MPa to 1.5 GPa

2021 ◽  
Vol 11 (12) ◽  
pp. 5728
Author(s):  
HyeonJeong You ◽  
Minjung Kang ◽  
Sung Yi ◽  
Soongkeun Hyun ◽  
Cheolhee Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Joint Strength ◽  
Solid Phase ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Friction Stir ◽  
Welding Processes

High-strength steels are being increasingly employed in the automotive industry, requiring efficient welding processes. This study analyzed the materials and mechanical properties of high-strength automotive steels with strengths ranging from 590 MPa to 1500 MPa, subjected to friction stir welding (FSW), which is a solid-phase welding process. The high-strength steels were hardened by a high fraction of martensite, and the welds were composed of a recrystallized zone (RZ), a partially recrystallized zone (PRZ), a tempered zone (TZ), and an unaffected base metal (BM). The RZ exhibited a higher hardness than the BM and was fully martensitic when the BM strength was 980 MPa or higher. When the BM strength was 780 MPa or higher, the PRZ and TZ softened owing to tempered martensitic formation and were the fracture locations in the tensile test, whereas BM fracture occurred in the tensile test of the 590 MPa steel weld. The joint strength, determined by the hardness and width of the softened zone, increased and then saturated with an increase in the BM strength. From the results, we can conclude that the thermal history and size of the PRZ and TZ should be controlled to enhance the joint strength of automotive steels.

scholarly journals Heat Treatment Design for a QP Steel: Effect of Partitioning Temperature

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1136
Author(s):  
Marcel Carpio ◽  
Jessica Calvo ◽  
Omar García ◽  
Juan Pablo Pedraza ◽  
José María Cabrera
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Quenching Temperature ◽  
Advanced High Strength Steels ◽  
New Family ◽  
Automotive Parts ◽  
Fresh Martensite ◽  
Industry Needs

Designing a new family of advanced high-strength steels (AHSSs) to develop automotive parts that cover early industry needs is the aim of many investigations. One of the candidates in the 3rd family of AHSS are the quenching and partitioning (QP) steels. These steels display an excellent relationship between strength and formability, making them able to fulfill the requirements of safety, while reducing automobile weight to enhance the performance during service. The main attribute of QP steels is the TRIP effect that retained austenite possesses, which allows a significant energy absorption during deformation. The present study is focused on evaluating some process parameters, especially the partitioning temperature, in the microstructures and mechanical properties attained during a QP process. An experimental steel (0.2C-3.5Mn-1.5Si (wt%)) was selected and heated according to the theoretical optimum quenching temperature. For this purpose, heat treatments in a quenching dilatometry and further microstructural and mechanical characterization were carried out by SEM, XRD, EBSD, and hardness and tensile tests, respectively. The samples showed a significant increment in the retained austenite at an increasing partitioning temperature, but with strong penalization on the final ductility due to the large amount of fresh martensite obtained as well.

Investigations on the Mechanical Properties and Formability of Friction Stir Welded Tailored Blanks

2007 ◽  
Vol 344 ◽  
pp. 143-150 ◽  
Author(s):  
Gianluca Buffa ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Detlev Staud
Keyword(s):  
Mechanical Properties ◽  
Stress Condition ◽  
Research Effort ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Friction Stir ◽  
Tailored Blanks ◽  
Sheet Stamping ◽  
Wide Range

Tight competition characterizing automotive industries in the last decades has determined a strong research effort aimed to improve utilized processes and materials in sheet stamping. As far as the latter are regarded light weight alloys, high strength steels and tailored blanks have been increasingly utilized with the aim to reduce parts weight and fuel consumptions. In the paper the mechanical properties and formability of tailored welded blanks made of a precipitation hardenable aluminum alloy but with different sheet thicknesses, have been investigated: both laser welding and friction stir welding have been developed to obtain the tailored blanks. For both welding operations a wide range of the thickness ratios has been considered. The formability of the obtained blanks has been characterized through tensile tests and cup deep drawing tests, in order to show the formability in dependency of the stress condition; what is more mechanical and metallurgical investigations have been made on the welded joints.

Tensile properties of the FFF-processed thermoplastic polyurethane (TPU) elastomer

2021 ◽  
Author(s):  
Budi Arifvianto ◽  
Teguh Nur Iman ◽  
Benidiktus Tulung Prayoga ◽  
Rini Dharmastiti ◽  
Urip Agus Salim ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Low Cost ◽  
Thermoplastic Polyurethane ◽  
High Strength ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Fused Filament Fabrication ◽  
Raster Angle ◽  
Manufacturing Techniques

Abstract Fused filament fabrication (FFF) has become one of the most popular, practical, and low-cost additive manufacturing techniques for fabricating geometrically-complex thermoplastic polyurethane (TPU) elastomer. However, there are still some uncertainties concerning the relationship between several operating parameters applied in this technique and the mechanical properties of the processed material. In this research, the influences of extruder temperature and raster orientation on the mechanical properties of the FFF-processed TPU elastomer were studied. A series of uniaxial tensile tests was carried out to determine tensile strength, strain, and elastic modulus of TPU elastomer that had been printed with various extruder temperatures, i.e., 190–230 °C, and raster angles, i.e., 0–90°. Thermal and chemical characterizations were also conducted to support the analysis in this research. The results obviously showed the ductile and elastic characteristics of the FFF-processed TPU, with specific tensile strength and strain that could reach up to 39 MPa and 600%, respectively. The failure mechanisms operating on the FFF-processed TPU and the result of stress analysis by using the developed Mohr’s circle are also discussed in this paper. In conclusion, the extrusion temperature of 200 °C and raster angle of 0° could be preferred to be applied in the FFF process to achieve high strength and ductile TPU elastomer.

scholarly journals Substructure Development and Damage Initiation in a Carbide-Free Bainitic Steel upon Tensile Test

Metals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1261
Author(s):  
Mari Carmen Taboada ◽  
Amaia Iza-Mendia ◽  
Isabel Gutiérrez ◽  
Denis Jorge-Badiola
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Formation Mechanisms ◽  
Tempered Martensite ◽  
Damage Initiation ◽  
Advanced High Strength Steels ◽  
Significant Strength ◽  
The Stability

Carbide-free bainitic (CFB) steels belong to the family of advanced high strength steels (AHSS) that are struggling to become part of the third-generation steels to be marketed for the automotive industry. The combined effects of the bainitic matrix and the retained austenite confers a significant strength with a remarkable ductility to these steels. However, CFB steels usually show much more complex microstructures that also contain MA (Martensite–Austenite) phase and auto-tempered martensite (ATM). These phases may compromise the ductility of CFB steels. The present work analyzes the substructure evolution during tensile tests in the necking zone, and deepens into the void and crack formation mechanisms and their relationship with the local microstructure. The combination of FEG-SEM imaging, EBSD, and X-ray diffraction has been necessary to characterize the substructure development and damage initiation. The bainite matrix has shown great ductility through the generation of high angle grain boundaries and/or large orientation gradients around voids, which are usually found close to the bainite and MA/auto-tempered martensite interfaces or fragmenting the MA phase. Special attention has been paid to the stability of the retained austenite (RA) during the test, which may eventually be transformed into martensite (Transformation Induced Plasticity, or TRIP effect).

scholarly journals Numerical investigation on the forming behaviour of stainless/carbon steel bimetal composite

2018 ◽  
Vol 185 ◽  
pp. 00012
Author(s):  
Zhou Li ◽  
Jingwei Zhao ◽  
Qingfeng Zhang ◽  
Sihai Jiao ◽  
Zhengyi Jiang
Keyword(s):  
Carbon Steel ◽  
Circumferential Stress ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Composite Sheet ◽  
Forming Process ◽  
Thickness Strain ◽  
Forming Simulation ◽  
Bimetal Composite ◽  
Forming Behaviour

Bimetal composites have wide applications due to their excellent overall performance and relatively low comprehensive cost. The aim of this study is to investigate the forming behaviour of stainless/carbon steel bimetal composite during stamping by finite element method (FEM). In this work, the bonding interface of bimetal composite sheet was assumed to be perfect without delamination during the plastic forming process for simplicity. Uniaxial tensile tests on base metal (carbon steel) and compositing metal (stainless steel) were first carried out, respectively, in order to obtain the tensile properties of each of the component materials required in the forming simulation. Processing variables, including the layer stacking sequence, relative thickness ratios of two layers and friction were considered, and their effects on the distributions of circumferential stress and thickness strain were analysed. The bimetal composite sheet was set as the eight-node solid elements in the developed FEM model, which is effective for evaluating the distributions of circumferential stress and thickness strain, and predicting the high-risk region of necking during the stamping of bimetal composites. The simulation results can be used as an evaluation indicator of the capability of forming machine to ensure the bimetal composite can be safely formed.

Sign in / Sign up

Export Citation Format

Share Document