scholarly journals Current Challenges and Opportunities in Microstructure-Related Properties of Advanced High-Strength Steels

2020 ◽  
Vol 51 (11) ◽  
pp. 5517-5586 ◽  
Author(s):  
Dierk Raabe ◽  
Binhan Sun ◽  
Alisson Kwiatkowski Da Silva ◽  
Baptiste Gault ◽  
Hung-Wei Yen ◽  
...  
Keyword(s):  
Recent Progress ◽  
High Strength Steels ◽  
High Strength ◽  
Advanced Characterization ◽  
Critical Discussion ◽  
Press Hardening ◽  
Advanced High Strength Steels ◽  
Bainitic Steels ◽  
Challenges And Opportunities ◽  
Recent Developments

Abstract This is a viewpoint paper on recent progress in the understanding of the microstructure–property relations of advanced high-strength steels (AHSS). These alloys constitute a class of high-strength, formable steels that are designed mainly as sheet products for the transportation sector. AHSS have often very complex and hierarchical microstructures consisting of ferrite, austenite, bainite, or martensite matrix or of duplex or even multiphase mixtures of these constituents, sometimes enriched with precipitates. This complexity makes it challenging to establish reliable and mechanism-based microstructure–property relationships. A number of excellent studies already exist about the different types of AHSS (such as dual-phase steels, complex phase steels, transformation-induced plasticity steels, twinning-induced plasticity steels, bainitic steels, quenching and partitioning steels, press hardening steels, etc.) and several overviews appeared in which their engineering features related to mechanical properties and forming were discussed. This article reviews recent progress in the understanding of microstructures and alloy design in this field, placing particular attention on the deformation and strain hardening mechanisms of Mn-containing steels that utilize complex dislocation substructures, nanoscale precipitation patterns, deformation-driven transformation, and twinning effects. Recent developments on microalloyed nanoprecipitation hardened and press hardening steels are also reviewed. Besides providing a critical discussion of their microstructures and properties, vital features such as their resistance to hydrogen embrittlement and damage formation are also evaluated. We also present latest progress in advanced characterization and modeling techniques applied to AHSS. Finally, emerging topics such as machine learning, through-process simulation, and additive manufacturing of AHSS are discussed. The aim of this viewpoint is to identify similarities in the deformation and damage mechanisms among these various types of advanced steels and to use these observations for their further development and maturation.

scholarly journals Boro-Austempering Treatment of High Strength Bainitic Steels

2019 ◽  
Author(s):  
Pedro Gabriel Bonella de Oliveira ◽  
Fábio Edson Mariani ◽  
Luiz Carlos Casteletti ◽  
André Itman Filho ◽  
Amadeu Lombardi Neto ◽  
...  
Keyword(s):  
Wear Resistance ◽  
High Strength Steels ◽  
Microscopic Analysis ◽  
High Strength ◽  
Salt Bath ◽  
Promising Alternative ◽  
Advanced High Strength Steels ◽  
Bainitic Steels ◽  
Work Samples ◽  
Bainite Microstructure

Abstract High strength bainitic steels are considered potential candidates for the 3rd generation of advanced high strength steels (AHSS). The main characteristic of silicon alloyed steels is the presence of carbide-free bainite, obtained by low temperature austempering. Salt bath boriding is an effective method for increasing wear resistance and provides high corrosion resistance. The combination of these two treatments is called boro-austempering and is a promising alternative to increase the wear resistance of AHSS. In the present work, samples were borided at 900°C for 2 hours, direct cooled from that temperature and isothermally held in salt bath at 360°C for 1 and 3 hours. The substrate and the layers produced were characterized by optical microscopy (OM), scanning electron microscopy (SEM), Vickers microhardness (HRV) and microadhesive wear tests. The tribological characteristics of the layers were compared with those of the substrate. The microscopic analysis showed the effectiveness of boroaustempering treatment in the production of carbide-free bainite microstructure and the surface borided layers. As a result, there were increases in surface wear resistance up to 2,6 times when compared to the substrate.

scholarly journals Third generation of advanced high strength sheet steels for the automotive sector : A literature review

2021 ◽  
Vol 11 (4) ◽  
pp. 241-247
Author(s):  
Meknassi Raid Fekhreddine ◽  
Miklós Tisza
Keyword(s):  
Literature Review ◽  
Bainitic Ferrite ◽  
High Strength Steels ◽  
High Strength ◽  
Third Generation ◽  
Sheet Steels ◽  
Advanced High Strength Steels ◽  
The Third ◽  
Recent Developments ◽  
Steel Grades

The modern vehicles demand a better fuel economy, decrease in ozone harming substance outflows, and superior safety requirements led to new developments of steel grades with higher strength and good formability. Third generation of advanced high strength steels are the next stage for the automotive companies in steel sheets development. The principal concept of third generation of AHSS is to reap the mechanical properties benefits from first and second generation of AHSS at cost neither too high nor too low. This literature review summarizes the results achieved in a previous paper of the Third Generation of Advanced High Strength Sheet steels literature published by D. Krizan et al. Where we intend to focus on, the recent developments and future trends of the third generation of advanced high strength sheet steels (3-GEN AHSSs) including quenching and partitioning (Q&P), TRIP bainitic ferrite (TBF), medium manganese, density reduced TRIP (δ-TRIP) and nano steels for the modern automotive industry, with emphasis on their main characteristics, processing, and applications.

scholarly journals Integration of Press-Hardening Technology into Processing of Advanced High Strength Steels

2018 ◽  
Vol 941 ◽  
pp. 317-322 ◽  
Author(s):  
Hana Jirková ◽  
Kateřina Opatová ◽  
Josef Káňa ◽  
Dagmar Bublíková ◽  
Martin Bystrianský
Keyword(s):  
Isothermal Holding ◽  
High Strength Steels ◽  
Dimensional Accuracy ◽  
High Strength ◽  
Total Elongation ◽  
Press Hardening ◽  
Advanced High Strength Steels ◽  
Passenger Safety ◽  
Ultra High Strength Steels ◽  
New Processing

Development of high strength or even ultra-high strength steels is mainly driven by the automotive industry which strives to reduce the weight of individual parts, fuel consumption, and CO2 emissions. Another important factor is the passenger safety which will improve by the use of these materials. In order to achieve the required mechanical properties, it is necessary to use suitable heat treatment in addition to an appropriate alloying strategy. The main problem of these treatments is the isothermal holding time. These holding times are technologically demanding which is why industry seeks new possibilities to integrate new processing methods directly into the production process. One option for making high-strength sheet metals is press-hardening which delivers high dimensional accuracy and a small spring-back effect. In order to test the use of AHSS steels for this technology, a material-technological modelling was chosen. Material-technological models based on data obtained directly from a real press-hardening process were examined on two experimental steels, CMnSi TRIP and 42SiCr. Variants with isothermal holding and continuous cooling profiles were tested. It was found that by integrating the Q&P process (quenching and partitioning) into press hardening, the 42SiCr steel can develop strengths of over 1800 MPa with a total elongation of about 10%. The CMnSi TRIP steel with lower carbon content and without chromium achieved a tensile strength of 1160 MPa with a total elongation of 10%.

scholarly journals Recent Progress in Understanding the Nano/Micro-Mechanical Behavior of Austenite in Advanced High Strength Steels

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1927
Author(s):  
Qingwen Guan ◽  
Wenjun Lu ◽  
Binbin He
Keyword(s):  
Mechanical Behavior ◽  
High Performance ◽  
Recent Progress ◽  
Low Cost ◽  
High Strength Steels ◽  
High Strength ◽  
Small Scale ◽  
Advanced High Strength Steels ◽  
Dislocation Plasticity ◽  
Austenite Grains

Advanced high strength steels (AHSS) are developed to reduce vehicle weight without sacrificing passenger safety. The newly developed AHSS frequently incorporates the austenite as the intrinsic component with large amount and good stability, which is realized by carefully designed alloying elements and thermo-mechanical processing. To explore the great potential of austenite in enhancing the strain hardening behavior of AHSS, detailed information on the mechanical behavior of single austenite grain is a prerequisite, which can be collected by a small-scale test. The present work reviews the recent progress in understanding the nano/micro-mechanical behavior of austenite in varied AHSS. Three different plasticity modes including dislocation plasticity, martensitic transformation, and deformation twinning can be observed in the austenite grains during small-scale tests, given proper stacking fault energy and crystal orientation. The remaining issues concerned with the nano/micro-mechanical behavior of austenite are discussed. The present review advances the general understanding of the nano/micro-mechanical behavior of austenite grains in AHSS, which may shed light on the precise austenite engineering with the development of new AHSS, realizing the dream of high-performance steels at low cost.

scholarly journals Critical Assessment of Techniques for the Description of the Phase Composition of Advanced High-Strength Steels

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4033 ◽  
Author(s):  
Anna Knaislová ◽  
Darya Rudomilova ◽  
Pavel Novák ◽  
Tomáš Prošek ◽  
Alena Michalcová ◽  
...  
Keyword(s):  
Phase Composition ◽  
Retained Austenite ◽  
Density Ratio ◽  
High Strength Steels ◽  
High Strength ◽  
Advanced Characterization ◽  
Minor Amount ◽  
Advanced High Strength Steels ◽  
Steel Grades ◽  
A Minor

The phase composition and portion of individual phases in advanced high-strength steels (AHSS) CP1000 and DP1000 was studied by complementary microscopic and diffraction techniques. CP1000 and DP1000 steel grades have a high strength-to-density ratio and they are used in many applications in the automotive industry. The microstructure of the CP1000 “complex phase” steel consists of ferrite, bainite, martensite and a small amount of retained austenite. DP1000 is a dual phase steel, which has a structure of a ferritic matrix with islands of martensite and a minor amount of retained austenite. The influence of selected etchants (Nital, LePera, Beraha I, Nital followed by metabisulfite, Nital followed by LePera, and Nital followed by Beraha I) on the microstructure image is described. X-ray diffraction, neutron diffraction and light optical, scanning and transmission electron microscopy were used in this work for advanced characterization of the microstructure and phase composition. The information provided by each technique is critically compared.

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