Application of Dual-Phase and TRIP Steels on the Improvement of Crashworthy Structures

2005 ◽  
Vol 502 ◽  
pp. 181-188 ◽  
Author(s):  
Nuno Peixinho ◽  
N. Jones ◽  
António Pinho
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Dual Phase ◽  
Strain Rates ◽  
Trip Steels ◽  
Advanced High Strength Steels ◽  
Steel Grades ◽  
Determination Of Parameters

The improvements in vehicle crashworthiness observed in recent years have been closely linked to advanced high-strength steels that are currently being produced or in process of development. Amongst these, Dual-Phase and TRIP (Transformation Induced Plasticity) steels have presented excellent properties for use in crashworthy structures. For these steel grades an understanding of material behaviour at relevant strain rates is needed as well as constitutiv eequations suitable for use in analytic and numerical calculations. In this study the crashworthiness of thin-walled sections made of Dual-Phase and TRIP steels was investigated. Tensile tests were performed at different strain rates in a range of interest for crashworthiness problems. The results allowed the determination of parameters of Cowper-Symonds equation. Crush tests were performed at different speeds for top-hat and hexagonal tubes manufactured using laser welding. The experimental results were compared with numerical simulations obtained with LS-DYNA software. The influence of different material parameters on the accuracy of the simulations was examined.

Application of Advanced Multiphase Steels in Crashworthiness Structures: Experimental Study and Constitutive Equations

2006 ◽  
Vol 514-516 ◽  
pp. 579-583 ◽  
Author(s):  
Nuno Peixinho ◽  
António Pinho
Keyword(s):  
Constitutive Equations ◽  
Tensile Testing ◽  
High Strength Steels ◽  
High Strength ◽  
Experimental Program ◽  
Dual Phase ◽  
Strain Rates ◽  
Trip Steels ◽  
Advanced High Strength Steels ◽  
Steel Grades

This work presents results of tensile testing of advanced high strength steels of interest for crashworthy structures: Dual-Phase and TRIP (Transformation Induced Plasticity) steels. The improvements in vehicle crashworthiness observed in recent years have been closely linked to advanced high-strength steels that are currently being produced or in process of development. Amongst these, Dual-Phase and TRIP steels have presented excellent properties for use in crashworthy structures. For these steel grades an understanding of material behaviour at relevant strain rates is needed as well as constitutive equations suitable for use in analytic and numerical calculations. For that purpose an experimental program of tensile testing was performed in a range of strain rates of interest for crashworthiness problems: 0.0001 /s to 1000 /s. The test results were used to compare material properties and to evaluate the Cowper-Symonds constitutive equation and a modified version. Crush tests were performed at different speeds for top-hat and hexagonal tubes manufactured using laser welding and the results discussed in view of energy absorption.

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.

Niobium Containing Advanced High Strength Steels for Automotive Applications – Processing, Microstructure, and Properties

2013 ◽  
Vol 773-774 ◽  
pp. 325-335 ◽  
Author(s):  
Debanshu Bhattacharya
Keyword(s):  
Automotive Industry ◽  
Fuel Efficiency ◽  
High Strength Steels ◽  
High Strength ◽  
Dual Phase ◽  
Trip Steels ◽  
Advanced High Strength Steels ◽  
Energy Absorbing ◽  
Bake Hardenability ◽  
Very High

Two major drivers for the use of advanced steels in the automotive industry are fuel efficiency and increased safety performance. Fuel efficiency is mainly a function of weight of steel parts, which in turn, is controlled by gauge and design. Safety is determined by the energy absorbing capacity of the steel used to make the part. All of these factors are incentives for the automobile manufacturers to use Advanced High Strength Steels (AHSS) to replace the conventional steels used to manufacture automotive parts in the past. AHSS is a general term used to describe various families of steels. The most common AHSS is the dual-phase steel that consists of a ferrite-martensite microstructure. These steels are characterized by high strength, good ductility, low tensile to yield strength ratio and high bake-hardenability. Another class of AHSS is the complex-phase or multi-phase steel which has a complex microstructure consisting of various phase constituents and a high yield to tensile strength ratio. Transformation Induced Plasticity (TRIP) steels is another class of AHSS steels finding interest among the U.S. automakers. These steels consist of a ferrite-bainite microstructure with significant amount of retained austenite phase and show the highest combination of strength and elongation, so far, among the AHSS in use. High level of energy absorbing capacity combined with a sustained level of high n value up to the limit of uniform elongation as well as high bake hardenability make these steels particularly attractive for safety critical parts and parts needing complex forming. A relatively new class of AHSS is the Quenching and Partitioning (Q&P) steels. These steels seem to offer higher ductility than the dual-phase steels of similar strengths or similar ductility as the TRIP steels at higher strengths. Finally, martensitic steels with very high strengths are also in use for certain parts. The most recent initiative in the area of AHSS is the so-called 3rd Generation AHSS. These steels are designed to fill the region between the dual-phase/TRIP and the Twin Induced Plasticity (TWIP) steels with very high ductility at strength levels comparable to the conventional AHSS. Enhanced Q&P steels may be one method to achieve this target. Other ideas include TRIP assisted dual phase steels, high manganese steels and higher carbon TRIP type steels. In this paper, some of the above families of advanced high strength steels for the automotive industry will be discussed with particular emphasis on the role of niobium.

Influence of Microalloying Elements Ti and Nb on Recrystallization during Annealing of Advanced High-Strength Steels

2016 ◽  
Vol 879 ◽  
pp. 217-223 ◽  
Author(s):  
Marion Bellavoine ◽  
Myriam Dumont ◽  
Josée Drillet ◽  
Philippe Maugis ◽  
Véronique Hebert
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Solute Drag ◽  
Dual Phase ◽  
Comparative Efficiency ◽  
Advanced High Strength Steels ◽  
Steel Grades ◽  
Cold Rolled ◽  
Microalloying Elements ◽  
Predominant Effect

Microalloying elements Ti and Nb are commonly added to high-strength Dual Phase steels as they can provide efficient means for additional strengthening due to grain refinement and precipitation strengthening mechanisms. In the form of solute elements or as fine carbonitride precipitates, Ti and Nb are also expected to have a significant effect on the microstructural changes during annealing and especially on recrystallization kinetics. The present work investigates the influence of microalloying elements Ti and Nb on recrystallization in various cold-rolled Dual Phase steel grades with the same initial microstructure but different microalloying contents. Using complementary experimental and modeling approaches makes it possible to give some clarifications regarding both the nature of this effect and the comparative efficiency of Ti and Nb on delaying recrystallization. It is shown that niobium is the most efficient micro-alloying element to impede recrystallization and that the predominant effect is solute drag.

Modeling of C-Mn Chromium Containing Steel to Produce DP600 through Thin Slab Direct Rolling

2010 ◽  
Vol 638-642 ◽  
pp. 3502-3507
Author(s):  
M. Wagih ◽  
M. Shahtout ◽  
A. Kady
Keyword(s):  
Grain Size ◽  
High Strength Steels ◽  
High Strength ◽  
Production Costs ◽  
Dual Phase ◽  
Austenite Grain Size ◽  
Advanced High Strength Steels ◽  
Steel Grades ◽  
Direct Rolling ◽  
Part Complexity

The design of new steel grades and microstructures is mostly motivated by the necessity of steel industry to process always better suited high strength steel with low production costs. Automotive customers are asking for more steel options to meet increased specifications for strength, crash worthiness, energy absorption, part complexity, and dent resistance. To meet these requirements, new developed types of steel known as Advanced High-Strength Steels (AHSS) were introduced (e.g.: DP steel "Dual Phase", TRIP steel "Transformation Induced Plasticity",…etc). This paper presents a case study for producing DP600 dual phase steel in EZDK company through building up an integrated model to predicting both final austenite grain size after finishing rolling and the final ferrite grain size after cooling.

scholarly journals Arvedi ESP Technology - The Hot Rolling of HS and AHS Thin Gauge Steel Strips

2016 ◽  
Vol 854 ◽  
pp. 42-47 ◽  
Author(s):  
Roberto Venturini ◽  
Paolo Daniele Avancini ◽  
Nicola Barbier ◽  
Alessandro Rizzi
Keyword(s):  
Hot Rolling ◽  
Industrial Production ◽  
High Strength Steels ◽  
High Strength ◽  
Dual Phase ◽  
Advanced High Strength Steels ◽  
Steel Strips ◽  
Start Up ◽  
Steel Grades ◽  
Mechanical Investigation

After 5 years from start-up, Arvedi ESP Technology has achieved outstanding performances in terms of production, products and quality. The technology has proved particularly suitable for the production of thin gauge strips (< 2 mm). This paper presents the experiences in the production of high strength and advanced high strength steels, such as micro-alloyed S550MC, dual phase DP600 and ferritic bainitic HR60 in thin gauge strips on the ESP line of Acciaieria Arvedi S.p.A. in Cremona. Some aspects of the industrial production process for these steel grades are highlighted on the basis of casting and rolling parameters and microstructural and mechanical investigation.

Methodology for the Analysis of the Process Behaviour of Advanced High Strength Steels in Bending and Shearing Operations

2012 ◽  
Vol 504-506 ◽  
pp. 895-900 ◽  
Author(s):  
Ioannis Tsoupis ◽  
Sven Hildering ◽  
Marion Merklein
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Bending Tests ◽  
Advanced High Strength Steels ◽  
Damage And Failure ◽  
Out Of Plane ◽  
First Results ◽  
Steel Grades ◽  
Work First

In the automotive sector the application of advanced high strength steels (AHSS) for structural and safety relevant components plays an important role. Typical manufacturing processes concerning these parts are bending and cutting operations. However, the forming and cutting potential of these steel grades is different compared to conventional steels, as the process behaviour is changing. For an improved workpiece quality the fundamental knowledge of the damage and failure mechanisms is essential. This study presents a methodology for the analysis of AHSS in bending and out-of-plane shearing operations. Two micro alloyed high strength steels are investigated within this work. First results are presented concerning material characterisation by tensile tests, the material performance in air bending tests and the development of a modular punching tool. The study is closed by summarizing the damage behaviour along the process chain considering both bending and cutting. This shows the applicability of the presented methodology for analysing the process behaviour with respect to occurring failure.

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.

Influence of the Processing Variables on the Microstructure Evolution of a Bainitic Carbide-Free Steel

2016 ◽  
Vol 879 ◽  
pp. 867-872 ◽  
Author(s):  
M.C. Taboada ◽  
I. Gutiérrez ◽  
D. Jorge-Badiola ◽  
S.M.C. van Bohemen ◽  
F. Hisker ◽  
...  
Keyword(s):  
Retained Austenite ◽  
High Strength Steels ◽  
High Strength ◽  
High Volume ◽  
X Ray Diffraction ◽  
Tempered Martensite ◽  
Trip Steels ◽  
Volume Fractions ◽  
Advanced High Strength Steels ◽  
Processing Variables

New trends focused on achieving higher performance steels has led to a so-called 3rd Generation Advanced High Strength Steels (AHSS), in which the typical polygonal ferrite found in TRIP steels as a matrix phase is replaced by harder phases as Carbide-Free Bainite (CFB) and/or (tempered) martensite. Besides, large volume fractions of retained austenite (R.A.) with adequate stability are aimed for to improve the formability of the steels. Si containing steels are regarded as the most suitable to retard cementite formation and consequently reach high volume fractions of RA. In this work, CFB annealing schedules were applied to dilatometer samples of Fe-0.22C-2.0Mn-1.3Si. The overaging temperature TB was varied between 390 oC and 480 oC, and other processing variables investigated were the austenitizing temperature Taus, and the overaging holding time tB. The annealed samples analyzed with LOM, FEG-SEM, EBSD and X-ray diffraction techniques show that markedly different complex microstructures made up of bainite, ferrite, MA phase and retained austenite (R.A) are accomplished depending on the specific thermal cycle. These results are described in detail and discussed in relation to the dilatometry measurements.

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).

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