Mechanical properties of ultra-high-strength steels at elevated temperatures

2019 ◽  
Vol 46 (10) ◽  
pp. 944-952
Author(s):  
Nuri Sen ◽  
Gökhan Durucan ◽  
Oktay Elkoca ◽  
İlyas Uygur
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
High Strength Steels ◽  
High Strength ◽  
Ultra High Strength Steels

Mechanical properties and microstructural evaluation of the heat-affected zone in ultra-high strength steels

2020 ◽  
Vol 157 ◽  
pp. 107072
Author(s):  
Mohsen Amraei ◽  
Shahriar Afkhami ◽  
Vahid Javaheri ◽  
Jari Larkiola ◽  
Tuomas Skriko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Affected Zone ◽  
High Strength Steels ◽  
High Strength ◽  
Microstructural Evaluation ◽  
Ultra High Strength Steels

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>

scholarly journals Post-fire mechanical properties of high strength steels

2018 ◽  
Author(s):  
Ben Young ◽  
Hai-Ting Li
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Ambient Temperature ◽  
High Strength Steel ◽  
Elevated Temperatures ◽  
Weight Ratio ◽  
High Strength Steels ◽  
High Strength ◽  
Predictive Equations ◽  
Retention Factors

High strength steels are becoming increasingly attractive for structural and architectural applications due to their superior strength-to-weight ratio which could lead to lighter and elegant structures. The stiffness and strength of high strength steels may reduce after exposure to fire. The post-fire mechanical properties of high strength steels have a crucial role in evaluating the residual strengths of these materials. This paper presents an experimental investigation on post-fire mechanical properties of cold-formed high strength steels. A series of tensile coupon tests has been carried out. The coupon specimens were extracted from cold-formed square hollow sections with nominal yield stresses of 700 and 900 MPa at ambient temperature. The specimens were exposed to various elevated temperatures ranged from 200 to 1000 °C and then cooled down to ambient temperature before tested to failure. Stress-strain curves were obtained and the mechanical properties, namely, Young’s modulus, yield stress (0.2% proof stress) and ultimate strength, of the cold-formed high strength steel materials after exposure to elevated temperatures were derived. The post-fire retention factors that obtained from the experimental investigation were compared with existing predictive equations in the literature. New predictive equations are proposed to determine the residual mechanical properties of high strength steels after exposure to fire. It is shown that the proposed predictive equations are suitable for both cold-formed and hot-rolled high strength steel materials with nominal yield stresses ranged from 690 to 960 MPa.

Mechanical Behaviour of Ceramic Beads Used as Medium for Hydroforming at Elevated Temperatures

2009 ◽  
Vol 410-411 ◽  
pp. 61-68 ◽  
Author(s):  
Marion Merklein ◽  
Martin Grüner
Keyword(s):  
Granular Material ◽  
Elevated Temperatures ◽  
Exhaust System ◽  
High Strength Steels ◽  
High Strength ◽  
Compression Direction ◽  
High Efficient ◽  
Hydroforming Process ◽  
Ultra High Strength Steels

The need of light weight construction for high efficient vehicles leads to the use of new materials like aluminium and magnesium alloys or high strength and ultra high strength steels. At elevated temperatures the formability of steel increases as the flow stresses decrease. Forming high complex geometries like chassis components or components of the exhaust system of vehicles can be done by hydroforming. The hydroforming process by oils is limited to temperatures of approximately 300 °C and brings disadvantages of possible leakage and fouling. Using granular material like small ceramic beads as medium could be an approach for hydroforming of ultra high strength steels like MS W1200 and CP W800 at temperatures up to 600 °C. The material properties of granular material are in some points similar to solid bodies, in other points similar to liquids. For understanding and simulation of the behaviour of the medium a basic characterisation of ceramic beads with different ball diameters is necessary. Powder mechanics and soil engineering give ideas for experimental setups. For the conversion of these approaches on the one hand the behaviour of the ceramic beads itself has to be characterized, on the other hand the contact between a blank and the beads have to be investigated. For the tests three different kinds of spheres with a diameter between 63 microns and 850 microns are used. In unidirectional compression test compressibility, pressure distribution in compression direction and transversal compression direction and the effect of bead fracture are investigated. The tests are carried out at different compression velocities and for multiple compressions. For determination of friction coefficients between blank and beads and determination of shear stress in bulk under compression a modified Jenike-Shear-Cell for use in universal testing machines with the possibility of hydraulic compression of the beads is built up. The gained data can be used for material modelling in ABAQUS using Mohr-Coulomb or Drucker-Prager model.

Mechanical properties and microstructure of low carbon ultra-high strength steels (UHSS) microalloyed with boron

2012 ◽  
Vol 1373 ◽  
Author(s):  
I. Mejía ◽  
A. García de la Rosa ◽  
A. Bedolla-Jacuinde ◽  
J.M. Cabrera
Keyword(s):  
Mechanical Properties ◽  
Research Work ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Low Carbon ◽  
Advanced High Strength Steels ◽  
New Family ◽  
Ultra High Strength Steels ◽  
Hot Rolled

ABSTRACTThe aim of this research work is to study the effect of boron addition on mechanical properties and microstructure of a new family of low carbon NiCrVCu advanced high strength steels (AHSS). Experimental steels are thermo-mechanically processed (TMP) (hot-rolled+quenched). Results show that the microstructure of these steels contains bainite and martensite, predominantly, which nucleate along prior austenite grain boundaries (GB). On the other hand, tensile tests reveal that the TMP steels have YS (0.2% offset) of 978 MPa, UTS of 1140 MPa and EL of 18%. On the basis of exhibited microstructure and mechanical properties, these experimental steels are classified as bainitic-martensitic complex phase (CP) advanced ultra-high strength steels (UHSS).

scholarly journals Understanding Mechanical Properties of Nano-Grained Bainitic Steels from Multiscale Structural Analysis

Metals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 426 ◽  
Author(s):  
Caballero ◽  
Rementeria ◽  
Morales-Rivas ◽  
Benito-Alfonso ◽  
Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Strength Steels ◽  
High Strength ◽  
Extreme Conditions ◽  
Transformation Theory ◽  
Enabling Technology ◽  
Bainitic Steels ◽  
Steel Sector ◽  
Hardening Mechanisms ◽  
Ultra High Strength Steels

Steel components working in extreme conditions require materials presenting the highest performances. Nowadays, nanoengineering is being applied to the development of ultra-high strength steels as a key-enabling technology in the steel sector. The present article describes the multiscale structure of nano-grained steels designed using atomic transformation theory and processed by a simple heat treatment. Outstanding mechanical properties for these novel steels are reported, and strain-hardening mechanisms are discussed.

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