scholarly journals EFFECT OF LASER WELDING ON SAFETY CHARACTERISTICS OF HIGH STRENGTH STEELS SHEETS

2015 ◽  
Vol 21 (3) ◽  
pp. 184 ◽  
Author(s):  
Emil Evin ◽  
Stanislav Németh ◽  
Miroslav Tomáš
Keyword(s):  
Phase Structure ◽  
High Strength Steels ◽  
Material Constant ◽  
High Strength ◽  
Residual Austenite ◽  
Absorption Capacity ◽  
Fibre Laser ◽  
Strain Hardening Exponent ◽  
Strength And Stiffness ◽  
Multi Phase

In the automotive industry considerable attention is paid to innovations oriented especially to meeting safety and environmental requirements. Concepts of vehicle safety focus on resistance of deformation zone components to impact and resistance to intrusion of undesirable fragments into the passengers´ space. In terms of these aspects the samples of the base materials from micro-alloyed steels HSLA - H220PD, DP 600 and TRIP - RAK 40/70 and also welded by solid-state fibre laser YLS-5000 were analysed. Multi-phase structure materials TRIP - RAK 40/70 and DP 600 showed considerably higher values of absorption capacity, strength, and stiffness than in case of single-phase structure material HSLA - H220PD. The greatest values of absorption capacity, strength, and stiffness were recorded in material TRIP - RAK 40/70 with ferritic matrix and a certain fraction of residual austenite, bainite, and martensite. Absorption capacity, strength, and stiffness have strong correlation with material constant K and strain hardening exponent.

Characterization of Metallurgical Transformations in Multi-Phase High Strength Steels by Barkhausen Noise Measurement

2007 ◽  
Vol 539-543 ◽  
pp. 4283-4288
Author(s):  
Aurélie Hug-Amalric ◽  
Xavier Kleber ◽  
Jacques Merlin ◽  
Hélène Petitgand ◽  
Philip Meilland
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Residual Austenite ◽  
Noise Measurement ◽  
Barkhausen Noise ◽  
Dual Phase ◽  
Magnetic Barkhausen Noise ◽  
Noise Measurements ◽  
Multi Phase

The potentialities of using the magnetic Barkhausen noise measurement in characterization of metallurgical transformations have been highlighted in multi-phase High Strength (HS) steels. This kind of steels are composed of different metallurgical constituents, such as ferrite, bainite, martensite or residual austenite. Recently, we found that it was possible to assess the proportion of phases in ferrite-martensite steels and in industrial Dual-Phase steels too. In this work, we show that the Barkhausen noise measurements can be also suitable to follow bainitic transformation in a TRIP steel.

scholarly journals Materials for Automotive Lightweighting

2019 ◽  
Vol 49 (1) ◽  
pp. 327-359 ◽  
Author(s):  
Alan Taub ◽  
Emmanuel De Moor ◽  
Alan Luo ◽  
David K. Matlock ◽  
John G. Speer ◽  
...  
Keyword(s):  
Galvanic Corrosion ◽  
Low Carbon Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
New Materials ◽  
Specific Strength ◽  
Advanced High Strength Steels ◽  
Strength And Stiffness ◽  
The Cost

Reducing the weight of automobiles is a major contributor to increased fuel economy. The baseline materials for vehicle construction, low-carbon steel and cast iron, are being replaced by materials with higher specific strength and stiffness: advanced high-strength steels, aluminum, magnesium, and polymer composites. The key challenge is to reduce the cost of manufacturing structures with these new materials. Maximizing the weight reduction requires optimized designs utilizing multimaterials in various forms. This use of mixed materials presents additional challenges in joining and preventing galvanic corrosion.

scholarly journals USE OF MULTI-PHASE TRIP STEEL FOR PRESS-HARDENING TECHNOLOGY

2019 ◽  
Vol 25 (2) ◽  
pp. 101 ◽  
Author(s):  
Hana Jirková ◽  
Kateřina Opatová ◽  
Štěpán Jeníček ◽  
Jiří Vrtáček ◽  
Ludmila Kučerová ◽  
...  
Keyword(s):  
Trip Steel ◽  
Physical Simulation ◽  
Isothermal Holding ◽  
High Strength Steels ◽  
High Strength ◽  
Press Hardening ◽  
Passenger Safety ◽  
Ultra High Strength Steels ◽  
New Treatments ◽  
Multi Phase

<p class="AMSmaintext">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 CO<sub>2</sub> emissions. Another important factor is to improve passenger safety. 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 types of treatments is the isothermal holding step. For TRIP steels, the holding temperature lies in the field of bainitic transformation. These isothermal holds are economically demanding to perform in industrial conditions. Therefore new treatments without isothermal holds, which are possible to integrate directly into the production process, are searched. One way to produce high-strength sheet is the press-hardening technology. Physical simulation based on data from a real-world press-hardening process was tested on CMnSi TRIP steel. Mixed martensitic-bainitic structures with ferrite and retained austenite (RA) were obtained, having tensile strengths in excess of 1000 MPa.</p>

scholarly journals RESIDUAL STRENGTH OF STRUCTURAL STEELS: SN400, SM520 AND SM570

2016 ◽  
Author(s):  
In-Rak Choi ◽  
Kyung-Soo Chung
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
High Strength Steels ◽  
High Strength ◽  
Building Construction ◽  
Steel Plates ◽  
Seismic Resistance ◽  
Building Structures ◽  
Reliable Performance ◽  
Strength And Stiffness

<p>This paper presents post-fire mechanical properties of mild to high-strength steels commonly used in building structures in Korea. Steel is one of the main materials for building construction due to fast construction, light weight, and high seismic resistance. However, steel usually loses its strength and stiffness at elevated temperatures, especially over 600°C. But steel can regain some of its original mechanical properties after cooling down from the fire. Therefore, it is important to accurately evaluate the reliable performance of steel to reuse or repair the structures. For this reason, an experimental study was performed to examine the post-fire mechanical properties of steel plates SN400, SM520 and SM570 after cooling down from elevated temperatures up to 900°C. The post-fire stress-strain curves, elastic modulus, yield and ultimate strengths and residual factors were obtained and discussed.</p>

Design of Modern Steels for Automotive Application

2010 ◽  
Vol 638-642 ◽  
pp. 3111-3116 ◽  
Author(s):  
Harald Hofmann ◽  
Thomas Heller ◽  
Sascha Sikora
Keyword(s):  
High Strength Steels ◽  
Superplastic Forming ◽  
High Strength ◽  
Hot Forming ◽  
Automotive Application ◽  
Advanced High Strength Steels ◽  
Automobile Components ◽  
Multi Phase ◽  
Further Development ◽  
Complex Parts

Advanced high-strength steels offer a great potential for the further development of automobile bodies-in-white due to their combined mechanical properties of high formability and strength. New types of grades – multi-phase steels, superductile steels and density reduced steels – are under development at ThyssenKrupp Steel with tensile strength levels of up to 1000 MPa in combination with excellent formability for the high demands of cold formed structural automobile components. New forming technologies at increased temperatures – hot forming, semi-hot forming and superplastic forming - enable the processing of complex parts with extreme high strength. ThyssenKrupp Steel identifies potential future steels and technology concepts by technology monitoring and evaluates their potential for future applications in pre-development projects. University research institutions are significantly involved in this essential future oriented challenge. Seminal concepts are being implemented together with automotive manufactures by simultaneous engineering processes with coordinated phases of production and testing.

A study on different techniques of restoration of fire damaged reinforced concrete flexural members

2017 ◽  
Vol 8 (2) ◽  
pp. 131-148
Author(s):  
Danie Roy Anasco Bastin ◽  
Umesh Kumar Sharma ◽  
Pradeep Bhargava
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Elevated Temperatures ◽  
High Strength ◽  
Absorption Capacity ◽  
Rc Beams ◽  
Content Type ◽  
Flexural Failure ◽  
Externally Bonded ◽  
Strength And Stiffness

Purpose The main aim of this research was to investigate the effectiveness of various strengthening techniques in restoring the structural performance of reinforced concrete (RC) beams damaged by elevated temperatures. Design/methodology/approach Three different strengthening techniques, namely, high-strength fibre reinforced concrete (HSFRC), ferrocement (FC) jacketing and externally bonded fibre-reinforced polymer (FRP) were used. Series of RC beams were casted, heated, strengthened and tested to investigate the influence of various variables. The variables of the study were type of strengthening and level of heat damage. Findings Externally bonded FRP was found to be the best among the various techniques, especially with respect to strength and stiffness restoration. On the contrary, the FRP strengthening was not that effective in restoring the energy absorption capacity of beams compared to HSFRC and FC techniques of strengthening. The chosen strengthening techniques were able to restore the failure mode of beams to flexural failure, which was found to have changed to shear failure in case of heated unstrenghthened beams. Originality/value This research program has contributed to the fundamental understanding of designing post fire retrofit solutions for RC beams.

Manufacturing of Innovative Car Seat Components by Forming of Advanced High Strength Steels – Fundamental Research and Application

2009 ◽  
Vol 410-411 ◽  
pp. 3-11 ◽  
Author(s):  
Marion Merklein ◽  
Markus Kaupper
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Absorption Capacity ◽  
Car Seat ◽  
Advanced High Strength Steels ◽  
Steel Sheets ◽  
Transportation Sector ◽  
Steel Grades ◽  
Fundamental Research ◽  
Part Complexity

Nowadays advanced high strength steel sheets and related forming technologies play an important role in lightweight construction in the transportation sector. Since especially car seat components are subject to very strict safety demands, the application of these modern steel grades, which provide enhanced strength levels, seems to be a promising strategy to meet the challenge of reducing the sheet metal thickness while maintaining the crash energy absorption capacity. Concerning the high required level of part complexity and accuracy both the reduced formability and the increased springback tendency of advanced high strength steels are challenges for forming technologies compared to conventional steel grades. Against this background the forming potentials of advanced high strength steels are investigated and are made accessible for an application in structural car seat components. The analysis is to be done both experimentally and numerically, focusing on the finite element method (FEM) regarding a reliable process design.

scholarly journals Constitutive Model for Multi-phase High Strength Steels

2014 ◽  
Vol 81 ◽  
pp. 1204-1209 ◽  
Author(s):  
Wenjiao Dan ◽  
Weigang Zhang ◽  
Fei Liu
Keyword(s):  
Constitutive Model ◽  
High Strength Steels ◽  
High Strength ◽  
Multi Phase

Effect of Martensite in Initial Structure on Bainite Transformation

2010 ◽  
Vol 638-642 ◽  
pp. 3307-3312 ◽  
Author(s):  
Hiroyuki Kawata ◽  
Kunio Hayashi ◽  
Natsuko Sugiura ◽  
Naoki Yoshinaga ◽  
Manabu Takahashi
Keyword(s):  
Transformation Temperature ◽  
Phase Structure ◽  
Bainitic Ferrite ◽  
High Strength Steels ◽  
High Strength ◽  
Nucleation Site ◽  
Second Phase ◽  
Initial Structure ◽  
Bainite Transformation ◽  
Ultra High Strength Steels

Lath-shaped upper bainite structures play a very important role in many high-strength steels (HSSs) and ultra high-strength steels (UHSSs). Although bainite transformation is strongly affected by the initial structure, the effect of the second phase in a multi-phase structure is yet to be clearly understood. It is significant for the advancement of UHSS to study this effect. The aim of this study is to clarify the effect of martensite, which forms before bainite, in Fe-0.2C-8Ni alloy. The bainite transformation from an austenite and martensite dual-phase structure is faster than that from single-phase austenite and the nucleation of bainitic ferrite laths are accelerated around martensite. This effect of martensite on bainite kinetics is equivalent to that of polygonal ferrite when their volume fractions are almost the same. This suggests that the boundary between martensite and austenite is a prior nucleation site of bainitic ferrite. Martensite also affects the crystallographic features of bainite. The orientations of bainitic ferrite laths tend to belong to the same block with martensite adjacent. This tendency intensifies with an increase of the transformation temperature of bainite, resulting in the formation of huge blocks consisting of bainitic ferrite and martensite laths at high temperatures (693K and 723K). In contrast, at a low temperature (643K), bainitic ferrite laths belong to same packet as martensite and have several orientations. This change of crystallographic features with transformation temperature can explain with the driving force of the nucleation of bainitic ferrite.

Numerical Simulation of Impact Events of the Ultimate Metallic Toe Cap Model for Safety Footwear

2014 ◽  
Author(s):  
Sérgio L. Costa ◽  
Nuno Peixinho ◽  
João P. Mendonça
Keyword(s):  
Test Performance ◽  
High Strength Steels ◽  
High Strength ◽  
Deformation Mode ◽  
Absorption Capacity ◽  
Crash Test ◽  
Prototype Model ◽  
Full Potential ◽  
Element Analysis ◽  
Constitutive Parameters

In this paper the normative impact-crash test in the context of the experimental validation of the last and final approved prototype model is focused. The project S3 – Safety Slim Shoe presents the potential to reduce the weight in safety toe cap components combining a new geometric redesign deeply associated to local stiffeners to realize the full potential of AHSS – Advanced High Strength Steels. The investigation aimed to investigate the potential energy absorption capacity for a substantial thickness reduction of a new engineering geometry with evaluative corrections for the specific impact test performance. A set of FEA - Finite Element Analysis of the plastic deformation mode was performed, and some material parameters such as: hardening effects and sensitivity for material constitutive parameters with demanding test strain rates were carried out. Experimental results of the toe cap deformation behavior confront a weight saving range of over 40%, compared with the original steel toe cap.

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