scholarly journals Changes of microstructure and mechanical properties of the HAZ of the S960MC steel sheet weld joint

2020 ◽  
Vol 65 (3) ◽  
pp. 113-123
Author(s):  
Miloš Mičian ◽  
Milan Maronek ◽  
Radoslav Konar ◽  
Daniel Harmaniak ◽  
Mihal Jambor ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Welded Joint ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Coarse Grain ◽  
Fine Grain ◽  
Microstructural Evaluation ◽  
Ultra High Strength Steels

The TMCP (thermo-mechanically controlled processed) steels belong to the group of ultra-high strength steels, which exhibit exceptional combination of high tensile and yield strength, toughness and ductility. These steels were introduced in the heavy machinery constructions, such as heavy mobile cranes, chassis trucks and other to reduce their weight, what increases their loading capacity and ecology of transport. The high tensile and yield strength of this type of steels is obtained by the combination of the chemical composition, heat treatment and the mechanical processing. However, the heat input into the material during the welding significantly affect properties of the steel and the whole joint. In this paper are presented results of mechanical properties evaluation and structural analysis of the welds of the thin sheets made of the S960MC steel, which were welded using the GMAW procedure. The microstructural evaluation referred significant changes in the HAZ. This area contains the three sub-zones, coarse grain (CGHAZ), fine grain (FGHAZ) and intercritical zone (ICHAZ). Analysis of microhardness and the tensile tests results showed, that ICHAZ is the most critical area of the whole welded joint.

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

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 The Ultimate Load Estimation of Welded Joints of High-Strength Steels subject to Mechanical and Geometric Heterogeneity

2020 ◽  
pp. 99-108
Author(s):  
S B Sapozhnikov ◽  
M A Ivanov ◽  
I A Shcherbakov
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Base Metal ◽  
Welded Joints ◽  
Stress Concentrator ◽  
Ultimate Load ◽  
Welded Joint ◽  
High Strength Steels ◽  
High Strength ◽  
Welding Wire

In this paper we consider the problems arising in the numerical estimation of the ultimate load of welded joints of high-strength steels with slight hardening. The stress concentrator in the transition node from the deposited to the base metal is modeled based on the example of welding a roller wire on a plate made of high-strength steel. The use of welding wire with a yield point lower than that of the base metal allowed to simulate areas of the welded joint with heterogeneous mechanical properties. The geometry of three areas of the welded joint is studied, i.e. weld metal, heat-affected zone (HAZ) and the base metal. Mechanical properties of all three areas are determined by calculation and experimentally. For this purpose, it is proposed to consider the material in all sections as ideally elastic-plastic, and the yield strength is uniquely associated with the hardness in the indentation zone (a Rockwell diamond cone is used). Calculations of the inelastic indentation process by the finite element method (FEM) in axis-symmetric formulation allowed obtaining a linear relationship between the hardness and the yield strength with a coefficient of 0.418. Tests at a quasi-static three-point bend (with stretching in the surfacing area) were carried out on sample beams cut perpendicular to the direction of welding. The “force-deflection” diagrams are obtained and compared with the calculated curves (FEM in a three-dimensional formulation with an explicit consideration of the complex configuration of all sections and different yield stress in the areas determined by local hardness values). There is a good agreement between the calculated and experimental ultimate loads. The proposed method of the three-stage study (determination of local hardness, yield strength in the areas and the ultimate load) can be effectively used to assess the ultimate loads of the welded joints due to the low parametricity of the proposed models of materials inelastic deformation in areas for which it is impossible to manufacture standard samples for the study of mechanical properties. The experimental study of the strengthening effect of the seam with a stress concentrator in the form of an angle of 90 degrees on the value of the ultimate bending load showed that the removal of the deposited metal does not lead to an increase in the ultimate load of the welded joint when using the welding wire of low-carbon high-plastic steel.

Investigations on the Mechanical Properties and Formability of Friction Stir Welded Tailored Blanks

2007 ◽  
Vol 344 ◽  
pp. 143-150 ◽  
Author(s):  
Gianluca Buffa ◽  
Livan Fratini ◽  
Marion Merklein ◽  
Detlev Staud
Keyword(s):  
Mechanical Properties ◽  
Stress Condition ◽  
Research Effort ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Friction Stir ◽  
Tailored Blanks ◽  
Sheet Stamping ◽  
Wide Range

Tight competition characterizing automotive industries in the last decades has determined a strong research effort aimed to improve utilized processes and materials in sheet stamping. As far as the latter are regarded light weight alloys, high strength steels and tailored blanks have been increasingly utilized with the aim to reduce parts weight and fuel consumptions. In the paper the mechanical properties and formability of tailored welded blanks made of a precipitation hardenable aluminum alloy but with different sheet thicknesses, have been investigated: both laser welding and friction stir welding have been developed to obtain the tailored blanks. For both welding operations a wide range of the thickness ratios has been considered. The formability of the obtained blanks has been characterized through tensile tests and cup deep drawing tests, in order to show the formability in dependency of the stress condition; what is more mechanical and metallurgical investigations have been made on the welded joints.

Characterization of Tempered 4340 Steel after 1200°C Austenitization

1980 ◽  
Vol 38 ◽  
pp. 380-381
Author(s):  
K. P. Datta ◽  
V. C. Kannan
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Yield Strength ◽  
High Strength Steels ◽  
High Strength ◽  
Subsequent Tempering ◽  
Considerable Research ◽  
4340 Steel ◽  
Ultra High Strength Steels

Considerable research is in progress to improve the fracture toughness of low alloy ultra-high strength steels such as 4340 while maintaining the same level of yield strength. One such methodis high temperature austenitization (1200° C). Subsequent tempering, in general, renders still higher toughness and hence this study is aimed at characterization of tempered 4340 steel after 1200° C austenitization.

INLAND HI-FORM

Alloy Digest ◽  
1978 ◽  
Vol 27 (5) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Yield Strength ◽  
High Strength Steels ◽  
High Strength ◽  
Heat Treating ◽  
Low Carbon ◽  
Bending Properties ◽  
Fine Grain ◽  
Low Sulfur ◽  
Minimum Yield

Abstract INLAND HI-FORM Steels are a low-carbon, low or intermediate-manganese, low-sulfur, aluminum-killed, fine-grain, columbium and/or phosphorus-bearing series of high-strength steels providing greatly enhanced forming and bending properties. These steels are furnished in minimum yield strength levels from 40,000 to 80,000 psi. They are used widely in the transportation and mobile-equipment industries. See also Ispat Inland Cal Hi-Form 80Y100T, Alloy Digest CS-136, May 2003. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SA-346. Producer or source: Ispat Inland Inc..

scholarly journals The Influence of Hot-Dip Galvanizing on the Mechanical Properties of High-Strength Steels

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5219
Author(s):  
Milan Šmak ◽  
Jaroslav Kubíček ◽  
Jiří Kala ◽  
Kamil Podaný ◽  
Jan Vaněrek
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Chemical Composition ◽  
Yield Strength ◽  
High Strength Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Steel Members ◽  
Different Types ◽  
Standard Quality

Modern high-strength steels achieve their strength exclusively through the manufacturing process, as the chemical composition of these steels is very similar to the composition of standard-quality steels. Typically, hot-dip galvanizing is used to form a protective zinc layer on the steel parts of structures; nonetheless, the material is exposed to high temperatures during the process. With high-strength steels, this can lead to deterioration of the mechanical properties. This study aims to experimentally examine and evaluate the extent of deterioration of the mechanical properties of high-strength-steel members. The effect was studied on specimens made of three different types of steel with the yield strength ranging from 460 to 1250 MPa. For each type of steel, selected mechanical properties—yield strength, tensile strength, and hardness—were determined on specimens with and without hot-dip galvanization, and the obtained results were mutually compared. Our study shows a significant impact of the hot-dip galvanization process on the mechanical properties of some high-strength steels. With the studied types of steel, the yield strength decreased by up to 18%, the tensile strength by up to 13%, and the hardness by up to 55%.

Microstructural Evolution and Tensile Strength of Laser-Welded Butt Joints of Ultra-High Strength Steels: Low and High Alloy Steels

2021 ◽  
Vol 883 ◽  
pp. 250-257
Author(s):  
Mikko Hietala ◽  
Atef Hamada ◽  
Markku Keskitalo ◽  
Matias Jaskari ◽  
Jani Kumpula ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Fusion Zone ◽  
Microstructural Evolution ◽  
Laser Energy ◽  
High Strength Steels ◽  
High Strength ◽  
Tensile Tests ◽  
Butt Joints ◽  
Dissimilar Joints ◽  
Ultra High Strength Steels

The present study is focused on joining two ultra-high strength steels plates of 3 mm thickness using laser-welding. Abrasion resistant steel with martensitic structure, tensile strength (Rm) ≥ 2 GPa, and cold-deformed austenitic stainless steel, Rm 1.3 GPa, were used for the dissimilar butt joints. Two different laser energy inputs, 160 and 320 J/mm, were presented during welding. The weld morphology and microstructural evolution of the fusion zone were recorded using optical microscopy and electron back scattering diffraction (EBSD), respectively. The mechanical properties of the dissimilar joints were evaluated by hardness measurements and tensile tests. It was found that fusion zone has undergone a change in morphology and microstructure during welding depending upon the energy input. Analysis of the microstructural evolution in the fusion zone by EBSD examination showed that the presence of a mixture of small austenite grains in a matrix of martensite. The changes in hardness profiles and tensile strength under the experimental parameters were further reported.

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