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

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4970
Author(s):  
Jacqueline Noder ◽  
Jon Edward Gutierrez ◽  
Amir Zhumagulov ◽  
James Dykeman ◽  
Hesham Ezzat ◽  
...  
Keyword(s):  
Large Strain ◽  
High Strength Steels ◽  
Rate Sensitivity ◽  
High Strength ◽  
Tensile Tests ◽  
Forming Limit ◽  
Third Generation ◽  
Advanced High Strength Steels ◽  
Dp Steels ◽  
Dp980 Steel

While the third generation of advanced high-strength steels (3rd Gen AHSS) have increasingly gained attention for automotive lightweighting, it remains unclear to what extent the developed methodologies for the conventional dual-phase (DP) steels are applicable to this new class of steels. The present paper provides a comprehensive study on the constitutive, formability, tribology, and fracture behavior of three commercial 3rd Gen AHSS with an ultimate strength level ranging from 980 to 1180 MPa which are contrasted with two DP steels of the same strength levels and the 590R AHSS. The hardening response to large strain levels was determined experimentally using tensile and shear tests and then evaluated in 3D simulations of tensile tests. In general, the strain rate sensitivity of the two 3rd Gen 1180 AHSS was significantly different as one grade exhibited larger transformation-induced behavior. The in-plane formability of the three 1180 MPa steels was similar but with a stark contrast in the local formability whereas the opposite trend was observed for the 3rd Gen 980 and the DP980 steel. The forming limit curves could be accurately predicted using the experimentally measured hardening behavior and the deterministic modified Bressan–Williams through-thickness shear model or the linearized Modified Maximum Force Criterion. The resistance to sliding of the three 3rd Gen AHSS in the Twist Compression Test revealed a comparable coefficient of friction to the 590R except for the electro-galvanized 3rd Gen 1180 V1. An efficient experimental approach to fracture characterization for AHSS was developed that exploits tool contact and bending to obtain fracture strains on the surface of the specimen by suppressing necking. Miniature conical hole expansion, biaxial punch tests, and the VDA 238-100 bend test were performed to construct stress-state dependent fracture loci for use in forming and crash simulations. It is demonstrated that, the 3rd Gen 1180 V2 can potentially replace the DP980 steel in terms of both the global and local formability.

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.

scholarly journals Experimental Characterization and Deterministic Prediction of In-Plane Formability of 3rd Generation Advanced High Strength Steels

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 902
Author(s):  
Jon Edward Gutierrez ◽  
Jacqueline Noder ◽  
Clifford Butcher
Keyword(s):  
Shear Fracture ◽  
High Strength Steels ◽  
High Strength ◽  
Forming Limit ◽  
Large Strains ◽  
Third Generation ◽  
Plane Shear ◽  
Stress Criterion ◽  
Advanced High Strength Steels ◽  
Biaxial Stretching

The objective of the current study is to develop a practical, deterministic approach to the prediction of the in-plane formability of two third generation advanced high-strength steels (AHSS) of 980 and 1180 MPa ultimate tensile strength using only quasi-static mechanical property data. The hardening response to large strains was experimentally measured with the use of simple shear and tensile tests and validated in tensile simulations. The process-corrected limit strains in the Nakazima and Marciniak tests were compared to various analytical Forming Limit Curve (FLC) models for in-plane stretching. It was observed that the widely-used Marciniak–Kuczynski model can adequately predict the experimental FLC in biaxial stretching but significantly underestimated the limit strains in uniaxial stretching for both third generation AHSS. The observed through-thickness shear fracture mode in biaxial stretching was reasonably well-captured by the Bressan–Williams (BW) instability model for the 1180 MPa steel. A proposed extension of the BW model to uniaxial tension by adoption of the maximum in-plane shear stress criterion (BWx model) provided superior experimental correlation relative to the zero-extension model of Hill that was too conservative. Finally, a linearized version of the modified maximum force criterion (MMFC) was proposed that markedly improved the correlation with the process-corrected FLC for in-plane stretching of AHSS. The developed framework for FLC prediction was then applied to a DP980 AHSS and an AA5182 aluminum alloy from the literature. The DP980 corroborated the observed trend for the two third generation AHSS whereas the MK and the BWx models performed best for the AA5182 with its saturation-type hardening behavior and non-quadratic yield surface.

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.

Third generation of advanced high-strength steels: Processing routes and properties

2016 ◽  
Vol 233 (2) ◽  
pp. 209-238 ◽  
Author(s):  
Tarun Nanda ◽  
Vishal Singh ◽  
Virender Singh ◽  
Arnab Chakraborty ◽  
Sandeep Sharma
Keyword(s):  
Automobile Industry ◽  
Second Generation ◽  
Low Cost ◽  
High Strength Steels ◽  
High Strength ◽  
Cost Effective ◽  
Processing Route ◽  
Third Generation ◽  
Specific Strength ◽  
Advanced High Strength Steels

The automobile industry is presently focusing on processing of advanced steels with superior strength–ductility combination and lesser weight as compared to conventional high-strength steels. Advanced high-strength steels are a new class of materials to meet the need of high specific strength while maintaining the high formability required for processing, and that too at reasonably low cost. First and second generation of advanced high-strength steels suffered from some limitations. First generation had high strength but low formability while second generation possessed both strength and ductility but was not cost effective. Amongst the different types of advanced high-strength steels grades, dual-phase steels, transformation-induced plasticity steels, and complex phase steels are considered as very good options for being extended into third generation advanced high-strength steels. The present review presents the various processing routes for these grades developed and discussed by different authors. A novel processing route known as quenching and partitioning route is also discussed. The review also discusses the resulting microstructures and mechanical properties achieved under various processing conditions. Finally, the key findings with regards to further research required for the processing of advanced high-strength steels of third generation have been discussed.

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).

Effect of Strain Paths on Formability Evaluation of TRIP Steels

2010 ◽  
Vol 89-91 ◽  
pp. 214-219 ◽  
Author(s):  
David Gutiérrez ◽  
A. Lara ◽  
Daniel Casellas ◽  
Jose Manuel Prado
Keyword(s):  
Strain Path ◽  
High Strength Steels ◽  
High Strength ◽  
Test Method ◽  
Forming Limit ◽  
Trip Steels ◽  
Advanced High Strength Steels ◽  
Strain Paths ◽  
Analysis System

The Forming Limit Diagrams (FLD) are widely used in the formability analysis of sheet metal to determine the maximum strain, which gives the Forming Limit Curve (FLC). It is well known that these curves depend on the strain path during forming and hence on the test method used to calculate them. In this paper, different stretching tests such as the Nakajima and the Marciniak tests were performed, with different sample geometries to obtain points in different areas of the FLD. An optical analysis system was used, which allows following the strain path during the test. The increasing use of advanced high-strength steels (AHSS) has created an interest in determining the mechanical properties of these materials. In this work, FLCs for a TRIP steel were determined using Nakajima and Marciniak tests, which revealed different strain paths depending on the type of test. Determination of the FLCs was carried out following the mathematical calculations indicated in the ISO 12004 standard and was also compared with an alternative mathematical method, which showed different FLCs. Finally, the tests were verified by comparing the strain paths of the Nakajima and Marciniak tests with a well-known mild steel.

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