scholarly journals Microstructure and residual stress analysis of Strenx 700 MC welded joint

2020 ◽  
Vol 26 (2) ◽  
pp. 41-44
Author(s):  
Libor Trško ◽  
Ján Lago ◽  
Michal Jambor ◽  
František Nový ◽  
Otakar Bokůvka ◽  
...  
Keyword(s):  
Residual Stress ◽  
Heat Affected Zone ◽  
Microstructural Analysis ◽  
Fatigue Crack Initiation ◽  
Welding Process ◽  
High Strength ◽  
Carbon Steels ◽  
Fatigue Properties ◽  
Residual Stress Field ◽  
Welded Structure

AbstractHigh strength low alloy (HSLA) steels are a new generation of plain carbon steels with significantly improved mechanical properties while maintaining good weldability with common commercial techniques. Residual stress and microstructural analysis of welded HSLA Strenx 700 MC was carried out in this research. Results have shown that the welding process causes significant grain coarsening in the heat affected zone. The microstructural changes are also accompanied with creation of tensile residual stress field in the weld metal and heat affected zone, reaching up-to depth of 4 mm. Tensile residual stresses are well known for acceleration of fatigue crack initiation and together with coarse grains can lead to significant decrease of the fatigue properties of the welded structure.

scholarly journals Fatigue Life Improvement of the High Strength Steel Welded Joints by Ultrasonic Impact Peening

Metals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 619 ◽  
Author(s):  
Ján Lago ◽  
Libor Trško ◽  
Michal Jambor ◽  
František Nový ◽  
Otakar Bokůvka ◽  
...  
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Welded Joints ◽  
Compressive Residual Stress ◽  
High Strength ◽  
Fatigue Properties ◽  
Low Alloy Steel ◽  
Residual Stress Field ◽  
Near Surface ◽  
Life Improvement

Ultrasonic impact peening was applied on welded joints manufactured from Strenx 700 MC high strength low alloy steel with the aim to improve the fatigue properties. Three different surface treatment parameters were tested, which resulted in transformation of the near-surface tensile residual stresses in the weld metal and heat affected zone to compressive residual stress field, while maximal values from −400 MPa up to −800 MPa were reached. The highest fatigue life improvement was reached by the double peening with the 85 N contact force, where the fatigue limit for N = 108 cycles increased from 370 MPa to 410 MPa.

scholarly journals Process Induced Residual Stress Effect on Fatigue Lifetime of Automotive Steel Components

2014 ◽  
Vol 996 ◽  
pp. 808-813
Author(s):  
Elias Merhy ◽  
Ngadia Taha Niane ◽  
Bastien Weber ◽  
Philippe Bristiel
Keyword(s):  
Residual Stress ◽  
Heat Affected Zone ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Welding Process ◽  
Fatigue Loading ◽  
Stress Effect ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Fatigue Lifetime

Metal Active Gas (MAG) welding process of steel sheets generates, in the vicinity of the welding joint, the well-known Heat Affected Zone (HAZ) in which the material presents more microstructural defects compared to the original metal. Since high cycle fatigue is largely dependent on the material microstructure features, the HAZ is considered as the weakest zone under high cycle fatigue loading. In addition, the welding causes, in the Heat Affected Zone, irreversible plastic strains that induce important residual stress fields in this critical zone of the structure. Therefore, in order to properly predict the high cycle fatigue life time of the welded automotive components, it is of primordial importance to first identify and then consider, if necessary, the welding induced residual stress field in the structure modeling. In this work, it is found that residual stresses have non-negligible impact on high cycle fatigue lifetime, while its effect is minor in the low cycle fatigue domain.

scholarly journals Finite Element Modelling of Laser Stitch Welding Joints for Structural Dynamic Predictions

2019 ◽  
Vol 16 (2) ◽  
pp. 6556-6567
Author(s):  
M. A. S. Aziz Shah ◽  
M. A. Yunus ◽  
M. N. Abdul Rani ◽  
M. S. Mohd Zin ◽  
W. I. I. Wan Iskandar Mirza
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Dynamic Behaviour ◽  
Welding Process ◽  
Shell Element ◽  
High Strength ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Structural Dynamic ◽  
Welded Structure

Laser stitch welding is a joining technique that has been increasingly popular in automotive industries, such as in the manufacturing and assembling of the car’s body-in-white (BiW) due to its advantages over the resistance spot weld, such as low heat application and high strength weld. The dynamic behaviour of a laser stitch welded structure is relatively difficult to predict accurately due to local parameters being induced during the laser welding process, such as heat affected zone (HAZ) and residual stress in the welded structure. This paper presents the idea of modelling the laser stitch weld by investigating different types of element connectors that can be used to represent laser stitch weld, such as rigid body element (RBE2), shell element (CQUAD4), bar element (CBAR) and area contact model (ACM2) format of element connectors. The accuracy of finite element models of laser stitch welded joints is compared in terms of natural frequencies and mode shapes with the experiment counterparts. The dynamic behaviour of the measured structure is obtained by using an impact hammer with free-free boundary conditions. It is found that the accuracy of the finite element models of the laser stitch welded structure highly depends on the involvement of residual stress and the heat affected zones that are generated from the welding process.

scholarly journals Numerical Simulation and Experimental Investigation of Temperature and Residual Stress Distributions in a Circular Patch Welded Structure

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5423 ◽  
Author(s):  
Mato Perić ◽  
Sandro Nižetić ◽  
Zdenko Tonković ◽  
Ivica Garašić ◽  
Ivan Horvat ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Welding Process ◽  
Infrared Camera ◽  
Circular Disk ◽  
Maximum Deviation ◽  
Cooling Process ◽  
Residual Stress Field ◽  
Circular Patch ◽  
Welded Structure

In this study, we performed a numerical simulation and experimental measurements on a steel circular patch welded structure to investigate the temperature and residual stress field distributions caused by the application of buried-arc welding technology. The temperature histories during the welding and subsequent cooling process were recorded for two locations, with the thermocouples mounted inside the plate close to the weld bead. On the upper surface of the welded model, the temperature-time changes during the cooling process were monitored using an infrared camera. The numerically calculated temperature values correlated well with the experimentally measured ones, while the maximum deviation of the measured and calculated temperatures was within 9%. Based on the numerical result analysis regarding circumferential and radial stresses after the completion of the welding process, it is concluded that both stresses are primarily tensile within the circular disk. Outside the disk, the circumferential stresses turn from tensile to compressive, while on the other hand the radial stresses disappear towards the ends of the plate.

scholarly journals Numerical study on the effect of welding and heating treatments on strength of high strength steel column

2018 ◽  
Author(s):  
Jiang Jin ◽  
Wei Bao ◽  
J. Liu ◽  
Z.Y. Peng
Keyword(s):  
Residual Stress ◽  
High Strength Steel ◽  
Arc Welding ◽  
Numerical Study ◽  
Welding Process ◽  
High Strength ◽  
Residual Stress Field ◽  
Heating Treatment ◽  
Welding Processes ◽  
Box Columns

High strength steel box columns are usually fabricated from steel slab by applying welding. The welding process can introduce residual stresses and geometric imperfections into the columns and influence the column strength. In this study, a numerical investigation on the behavior of high strength steel thin-walled box columns under the compression force was carried out. The welding processes were firstly simulated with commercial package ABAQUS in this study to find out the residual stress distributions in high strength steel box column. After that, the column behaviors under the compression were modelled with predefined field from the previous step. The effect of the welding process (including flux-core arc welding and submerged arc welding), heating treatment (including preheating and post-weld heat treatment) and geometrical imperfection on the residual stress field and box column strength was investigated and discussed.   

Influence of Shot Peening on Fatigue Properties in Ultra-High Strength Steels

2005 ◽  
Vol 490-491 ◽  
pp. 448-453 ◽  
Author(s):  
Yu Kui Gao ◽  
Xue Ren Wu ◽  
Feng Lu ◽  
Mei Yao ◽  
Qingxian Yan
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Limit ◽  
Surface Integrity ◽  
Shot Peening ◽  
Fatigue Crack Initiation ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Properties ◽  
Ultra High Strength Steels

The characteristics of compressive residual stress fields induced by shot peening in 40CrNi2Si2MoVA, 16Co14Ni10Cr2Mo, 30CrMnSiNi2A and 0Cr13Ni8Mo2Al ultra-high strength steels, which are used widely in aeronautical industry were investigated, and the change of surface integrity including surface residual stress, surface roughness as well as its effects on fatigue properties were investigated. The results show that the fatigue limits of ultra-high strength steels can be increased by shot peening because the surface integrity can be ameliorated by shot peening, and that for a given steel there is a appropriate peening intensity under which the fatigue property of this steel is optimum. Finally, a judgement for the optimization condition of shot peening process is proposed based on a theory of micro-meso processes of fatigue crack initiation and experimental results. The technique should be considered to be optimum, if the fatigue crack source of shot peened specimen has been moved to the internal matrix metal region beneath the hardened layer; and its apparent fatigue limit has been improved and got to a value, which is near to that predicted according to the concept of surface/internal fatigue limit.

scholarly journals Residual stresses in thermite welded rails: significance of additional forging

2020 ◽  
Vol 64 (7) ◽  
pp. 1195-1212
Author(s):  
B. Lennart Josefson ◽  
R. Bisschop ◽  
M. Messaadi ◽  
J. Hantusch
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Residual Stresses ◽  
Weld Metal ◽  
Welding Process ◽  
Surface Zone ◽  
Fe Model ◽  
Uneven Surface ◽  
Residual Stress Field ◽  
High Dynamic

Abstract The aluminothermic welding (ATW) process is the most commonly used welding process for welding rails (track) in the field. The large amount of weld metal added in the ATW process may result in a wide uneven surface zone on the rail head, which may, in rare cases, lead to irregularities in wear and plastic deformation due to high dynamic wheel-rail forces as wheels pass. The present paper studies the introduction of additional forging to the ATW process, intended to reduce the width of the zone affected by the heat input, while not creating a more detrimental residual stress field. Simulations using a novel thermo-mechanical FE model of the ATW process show that addition of a forging pressure leads to a somewhat smaller width of the zone affected by heat. This is also found in a metallurgical examination, showing that this zone (weld metal and heat-affected zone) is fully pearlitic. Only marginal differences are found in the residual stress field when additional forging is applied. In both cases, large tensile residual stresses are found in the rail web at the weld. Additional forging may increase the risk of hot cracking due to an increase in plastic strains within the welded area.

Low C High Mn Cold Rolled TWIP Steel: Kinetics of Isothermal Recrystallization

2012 ◽  
Vol 706-709 ◽  
pp. 2181-2186 ◽  
Author(s):  
Tulio M.F. Melo ◽  
Érica Ribeiro ◽  
Lorena Dutra ◽  
Dagoberto Brandão Santos
Keyword(s):  
Automobile Industry ◽  
Twip Steel ◽  
Volume Fraction ◽  
Microstructural Analysis ◽  
High Strength ◽  
Specific Weight ◽  
Carbon Steels ◽  
Cold Rolled ◽  
Increasing Demand ◽  
Kinetics Of

The increasing demand, mainly from the automobile industry, for materials which combine high strength, high ductility and low specific weight makes steels with the TWIP (TWinning Induced Plasticity) effect a promising material to meet these requirements. This work aimed to study the kinetics of isothermal recrystallization of a TWIP steel (C-0.06%, Mn-25%, Al-3%, Si-2%, and Ni-1%) after cold rolling. The steel was hot and cold-rolled and then annealed at 700°C with soaking times ranging from 10 to 7200 s. Microstructural analysis was performed using light (LM) and scanning electron microscopy (SEM). Furthermore, quantitative metallography was performed in order to evaluate the recrystallized volume fraction and grain size. A JMAK based model was applied to describe the nucleation grain growth process. The restoration of the steel was also evaluated by microhardness tests. A complete recrystallization after 7200 s at 700°C was observed. It was found that with increasing annealing times, the recrystallized volume fraction also increases, while the nucleation and growth rates decrease, in agreement with the results for plain carbon steels.

The Effect of Strength Mis-Match and Residual Stress in ECA of Girth Welds With Internal Circumferential Cracks

2009 ◽  
Author(s):  
Ali Mirzaee Sisan ◽  
Afshin Motarjemi
Keyword(s):  
Residual Stress ◽  
Stress Field ◽  
Driving Forces ◽  
Numerical Study ◽  
Welding Process ◽  
Detailed Comparison ◽  
Weld Strength ◽  
Residual Stress Field ◽  
Girth Welds ◽  
Welded Pipe

A numerical study was carried out to quantify the effect of a residual stress field on subsequent fracture behaviour of a girth welded pipe with an internal circumferential long crack when subjected to high applied strain loading. In order to introduce an initial residual stress field similar to a welding process in a pipe, a quenching process was numerically simulated and associated residual stress profiles were modified and mapped into the finite element (FE) models. A detailed comparison between the crack driving force for various cases with and without residual stress and weld strength mismatch was carried out for cases under a high plastic deformation regime. The BS7910 procedure was also used to predict crack driving forces using its current assumption of interaction of residual stress with primary loads. The results obtained from the FE analyses were compared with the BS7910 predictions.

scholarly journals Thermal Diffusivity of Traditional and Innovative Sheet Steels

2010 ◽  
Vol 297-301 ◽  
pp. 893-898
Author(s):  
Elena Campagnoli ◽  
Paolo Matteis ◽  
Giovanni M.M. Mortarino ◽  
Giorgio Scavino
Keyword(s):  
Thermal Diffusivity ◽  
Deep Drawing ◽  
Process Model ◽  
Twip Steel ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Carbon Steels ◽  
Low Carbon ◽  
Low Carbon Steels

The low carbon steels, used for the production of car bodies by deep drawing, are gradually substituted by high strength steels for vehicle weight reduction. The drawn car body components are joined by welding and the welded points undergo a reduction of the local tensile strength. In developing an accurate welding process model, able to optimized process parameters and to predict the final local microstructure, a significant improvement can be given by the knowledge of the welded steels thermal diffusivity at different temperatures. The laser-flash method has been used to compare the thermal diffusivity of two traditional deep drawing steels, two high strength steels already in common usage, i.e. a Dual Phase (DP) steel and a TRansformation Induced Plasticity (TRIP) steel, and one experimental high-Mn austenitic TWIP (Twinning Induced Plasticity) steel. The low carbon steels, at low temperatures, have a thermal diffusivity that is 4-5 times larger than the TWIP steel. Their thermal diffusivity decreases by increasing temperature while the TWIP steel shows an opposite behaviour, albeit with a lesser slope, so that above 700°C the TWIP thermal diffusivity is larger. The different behaviour of the TWIP steel in respect to the ferritic deep drawing steels arises from its non ferro-magnetic austenitic structure. The DP and TRIP steels show intermediate values, their diffusivity being lower than that of the traditional deep drawing steels; this latter fact probably arises from their higher alloy content and more complex microstructure.

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