scholarly journals Laser Welding of New Grade of Advanced High Strength Steel STRENX 1100 MC

2017 ◽  
Vol 62 (3) ◽  
pp. 1651-1657 ◽  
Author(s):  
A. Kurc-Lisiecka ◽  
J. Piwnik ◽  
A. Lisiecki
Keyword(s):  
Laser Welding ◽  
Base Metal ◽  
Mechanical Performance ◽  
High Strength ◽  
Carbon Equivalent ◽  
Welding Parameters ◽  
Low Carbon ◽  
Butt Joints ◽  
Significant Drop ◽  
Metal Impact

AbstractThe article presents results of investigations on autogenous laser welding of new grade STRENX 1100 MC steel. The modern Disk laser was applied for of 5.0 mm thick butt joints welding. The influence of laser welding parameters, mainly the energy input of laser welding on the penetration shape, weld quality, structure and mechanical performance was investigated. It was found that the investigated steel has surprisingly low carbon equivalent CET just 0.328, and also relatively high temperature of martensitic transformation Msat 430.6°C. Despite very rapid cooling times t8/5in a range from 0.6 to 1.3 s, thus rapid solidification there was no tendency to cracking of weld metal or HAZ. Significant drop of microhardness in the HAZ resulted in a decrease of tensile strength of joints, compared to the base metal. Impact toughness of test joints was at only 50÷60% of the base metal.

scholarly journals Imperfections and Modelling of the Weld Bead Profile of Laser Butt Joints in HSLA Steel Thin Plate

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 151
Author(s):  
Patricio G. Riofrío ◽  
José A. M. Ferreira ◽  
Carlos A. Capela
Keyword(s):  
Laser Welding ◽  
Welded Joints ◽  
Hsla Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Weld Bead ◽  
Welding Parameters ◽  
Great Decrease ◽  
Weld Quality ◽  
Butt Joints

In many applications that use high strength steels, structural integrity depends greatly on weld quality. Imperfections and the weld bead geometry are influencing factors on mechanical properties of the welded joints but, especially in the fatigue strength, they cause a great decrease. The proper knowledge of these two factors is important from the nominal stress approach to the fracture mechanics approaches. Studies concerning the profile and imperfections of the weld bead in laser welding for thin plates of high strength steels are scarce. In this work, these two aspects are covered for five series single and double-welded joints, butt joints in a 3 mm thick HSLA steel, welded in a small range of welding parameters. The actual profiles captured with profilometer were modeled with proposed geometric parameters achieving an adequate fit with values of the coefficient of determination ℜ2 greater than 0.9000. Description of imperfections includes the distributions of porosity and undercuts. The evaluation of the weld quality, taking as guide the ISO 13919-1 standard determined B and D levels for the welded series while based on the stress-concentrating effect, showed a greater detriment in those series with undercuts and excessive penetration. The analysis of variance validated the results of the different combinations of laser welding parameters and showed, for the factorial experimental design, a more significant effect of the welding speed.

Effect of Chemistry on the Fracture Toughness of Low Carbon X70 Girth Weld Heat Affected Zone

2014 ◽  
Author(s):  
M. Rashid ◽  
L. E. Collins ◽  
Y. Bian
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Heat Affected Zone ◽  
High Strength ◽  
Carbon Equivalent ◽  
Welding Parameters ◽  
Low Carbon ◽  
Girth Welds ◽  
Ferrite Nucleation ◽  
Linepipe Steel

Addition of alloying elements can alter the properties of high-strength linepipe steel. Particularly the addition of Chromium and Molybdenum acts to suppress ferrite nucleation and promote the formation of acicular bainite microstructures and thereby increase the tensile properties of modern linepipe steel. While chemistry is a factor, welding parameters can also be influential and affect the HAZ toughness. The present work compares the effect of C, Cr, and Mo on the girth weld HAZ fracture toughness of X70 in identical welds. Three pipes of size 48″ OD × 0.528″ WT with different combinations of C, Cr, and Mo were produced. Identical welding procedures were employed to produce two girth welds so that a low-C, Cr pipe (CE = 0.238) was joined to a high-C, Cr pipe (CE = 0.268) which in turn was joined to a low-C, Mo pipe (CE = 0.224). By evaluating the HAZ properties on either side of a weld, it was possible to accurately assess chemistry affects on HAZ properties. These girth welds were subjected to different testing for the evaluation of girth weld HAZ impact and fracture toughness. These included all-weld metal and pipe body tensile testing, micro hardness testing of HAZ, microstructure analysis, Charpy V-notch testing of weld metal and HAZ, and CTOD testing of weld metal and HAZ at −5 °C and −20 °C. In addition, to investigate the transformation behaviour, Gleeble simulations of coarse-grain heat affected zone (CG-HAZ) were conducted using skelp samples, which were taken from the same coils as the pipe samples. The results demonstrated that among the low and high carbon equivalent (CE) alloys, materials with low CE values showed better toughness properties. While among the low CE materials, the material with high Mo performed better in terms of toughness. No clear effect of weld position around the pipe circumference on the CTOD values was observed.

Analytical Study on Microstructure and Mechanical Property in HAZ-Softened Weld Joint with High Heat Input of Low Carbon TMCP Steel

2017 ◽  
Vol 872 ◽  
pp. 99-106
Author(s):  
Rong Zhi Mai ◽  
Ze Xin Jiang ◽  
Jin Jun Ma ◽  
Yong Jun Zhang
Keyword(s):  
Tensile Strength ◽  
Base Metal ◽  
Heat Input ◽  
High Strength ◽  
High Heat ◽  
Carbon Equivalent ◽  
Low Carbon ◽  
Fine Grain ◽  
High Heat Input ◽  
Softened Zone

Three types of low-carbon TMCP steels with different strength of the same carbon equivalent were welded by the flux-cupper back for SAW(FCB) method in this work. The microstructure, hardness and tensile strength of the FCB welded joints were studied. Softening phenomenon occurs in the heat affected zone of low-carbon content and low carbon-equivalent TMCP EH36 steel after high heat input welding. The softened zone is mainly depended on the strength of the base metal (BM), which appears on the fine-grain zone and incomplete crystallize zone of BM with relative low strength, and on the coarse grain zone of BM with high strength. The ratio of the tensile strength between each FCB joint and BM is the same of 0.98 as the same carbon and carbon equivalent content of 0.5% and 0.315% of BM, which is almost independent of the strength of BM. The tensile strength of the incomplete crystallize zone depends on the strength of the BM, which results in the improved strength of the whole softened zone with the increasing strength of base metal.

Analysis on Laser Welding of Hard Alloy Circular Saw Blades

2012 ◽  
Vol 155-156 ◽  
pp. 741-745 ◽  
Author(s):  
Qiang Wu ◽  
Lan Ying Xu ◽  
Xu Bo Yuan ◽  
Yu Zhong Li
Keyword(s):  
Laser Welding ◽  
Hard Alloy ◽  
Co2 Laser ◽  
Mechanical Performance ◽  
Matrix Material ◽  
Weld Line ◽  
Welding Parameters ◽  
Low Carbon ◽  
Circular Saw ◽  
Saw Blade

Based on a large number of CO2 laser welding tests to hard alloy saw blade cutter by PHC-1300 type laser of 1300W and TEM00 mode, and the laser welding parameters and weld microstructures were analyzed ,the mechanical performance tests were also done. The experimental results show that CO2 laser welding can improve combination strength and bearing capacity of the hard alloy circular saw blade cutter; the laser focal spot offset a distance from the weld line to the center of basal body, which can get the optimal weld line; selecting low carbon alloy steel as matrix material and selecting Co-based alloy as knife head lining material are suitable.

Effect of the Root Gap on the Structure and Properties of High Strength Steel S700MC Welds

2021 ◽  
Vol 890 ◽  
pp. 201-208
Author(s):  
Nikolay Ferdinandov ◽  
Danail Gospodinov ◽  
Mariana Ilieva ◽  
Rossen Radev
Keyword(s):  
High Strength Steels ◽  
High Strength ◽  
Pressure Vessels ◽  
Coarse Grained ◽  
Carbon Equivalent ◽  
Welding Parameters ◽  
Low Carbon ◽  
Negative Effect ◽  
Ultra High Strength Steels ◽  
Time Required

Nowadays, the use of high strength (HS) and ultra-high strength steels (UHS) increases, notably in welded constructions. These steels are mainly exploited in heavy loaded welded constructions such as bridges, cranes and excavators, in pressure vessels, vehicles, ships, drilling rigs etc. working at room or lower temperatures. As the welded constructions have specific requirements, the development of high strength and ultra-high strength steels imposes the need for research on the factors influencing their weldability. Among the possible negative implications are: cold cracks formation, softening of the heat affected zone, brittleness in the coarse grained zone. When complying with the generally accepted rules for welding, HS and UHS are readily welded by all conventional welding methods. Recommendations for welding of steels after normalization, thermo-mechanical treatment and quenching and tempering are given in the standard EN 1011 -1, 2. The use of thermo-mechanically treated (hot-rolled) steels with low carbon equivalent, such as S700MC, allows reduction in time required for welding as the preheating temperature is lowered or even preheating is not necessary. A more pronounced negative effect on the weld quality has the presence of different defects. S700MC can be welded by all conventional methods, and a reduction in the softened zone can be achieved by using appropriate welding parameters. Joint preparation for welding of HS and UHS steels is described in the standards EN ISO 9692-1:2013 and EN ISO 9692-2:2001. Nevertheless, the root gap is often the closing part in constructions and does not comply with the standard recommendations. That is why the effect of the root gap on welds has to be researched. The present work introduces results of a research studying the effect of the root gap on the structure and some mechanical and technological properties of S700MS welds, welded by submerged arc welding.

scholarly journals Welding of Thermomechanically Rolled Fine-Grain Steel by Different Types of Lasers/ Spawanie Stali Drobnoziarnistej Walcowanej Termomechanicznie Laserami Różnego Typu

2014 ◽  
Vol 59 (4) ◽  
pp. 1625-1631 ◽  
Author(s):  
A. Lisiecki
Keyword(s):  
Laser Welding ◽  
Diode Laser ◽  
Mechanical Performance ◽  
Welding Parameters ◽  
Butt Joints ◽  
Disk Laser ◽  
Fine Grain ◽  
Wide Range ◽  
Weld Porosity ◽  
Diode Laser Welding

Abstract The autogenous laser welding of 2.5 mm thick butt joints of thermomechanically rolled fine-grain steel grade S420MC was investigated. Butt joints were laser welded by the Yb:YAG Disk laser, emitted a circular laser beam with spot diameter of 200 μm at 1.03 μm wavelength, and also by the high power direct diode laser, emitted a rectangular beam with dimension of 1.8x6.8 mm at 808 nm wavelength. Different welding modes were identified for the lasers applied. The conduction welding mode was observed in whole of the diode laser welding parameters. While high quality joints, without any internal defects and characterized with satisfactory mechanical performance were produced in a wide range of parameters. The butt joints produced by Disk laser were welded at keyhole mode. In this case a slight tendency to weld porosity was found.

scholarly journals Laser Welding Dissimilar High-Strength Steel Alloys with Complex Geometries

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 792 ◽  
Author(s):  
Panos Efthymiadis ◽  
Khalid Nor
Keyword(s):  
Carbon Steel ◽  
Laser Welding ◽  
Cross Sections ◽  
High Carbon Steel ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
High Carbon ◽  
Material Chemistry ◽  
Metallurgical Defects

Laser welding of dissimilar high-strength steels was performed in this study for two different geometries, flat and circular samples with material thicknesses of 5 and 8 mm. The material combinations were a low carbon to a medium or high carbon steel. Three different welding systems were employed: a Nd:YAG, a CO2 and a fiber laser. The process stability was evaluated for all the experiments. The resulting full penetration welds were inspected for their surface quality at the top and bottom of the specimens. Cross sections were taken to investigate the resulting microstructures and the metallurgical defects of the welds, such as cracks and pores. Significant hardening occurred in the weld region and the highest hardness values occurred in the Heat Affected Zone (HAZ) of the high carbon steel. The occurrence of weld defects depends strongly on the component geometry. The resulting microstructures within the weld were also predicted using neural network-simulated Continuous Cooling Transformation (CCT) diagrams and predicted the occurrence of a mixture of microstructures, such as bainite, martensite and pearlite, depending on the material chemistry. The thermal fields were measured with thermocouples and revealed the strong influence of component geometry on the cooling rate which in term defines the microstructures forming in the weld and the occurring hardness.

scholarly journals Innovate Method for Friction Stir Welding of Al-Mg-Si Alloy Thin Plate

2019 ◽  
Vol 269 ◽  
pp. 02006
Author(s):  
Li Fu ◽  
Fenjun Liu
Keyword(s):  
Tensile Strength ◽  
Friction Stir Welding ◽  
Base Metal ◽  
High Speed ◽  
Thick Plate ◽  
Welding Parameters ◽  
Butt Joints ◽  
Friction Stir ◽  
High Rotation Speed ◽  
Precipitated Phases

Al-Mg-Si (6061-T6) alloy with 0.8 mm thick plate was welded successfully by use of high speed friction stir welding (FSW) technology. The microstructural characteristics and mechanical property of the butt joints prepared by high speed FSW were analyzed in detail, the influence of welding parameters, fixture condition and after welding heat treatment were also explored. The results shown that sound surface topography and defect-free bonding interface were observed in the nugget zone (NZ). The microhardness of the as-welded joint was lower than that of the base metal because of the welding heat effect. Compared with the conventional speed FSW, the number of β-Mg2Si, Al2CuMg and Al8Fe2Si precipitated phases existed in the high speed FSWed NZ increased, which made the microhardness in the NZ improved significantly. The rod-shaped precipitates (Mg2Si) have the greatest influence on the microhardness distributions. The maximum tensile strength of 301.8 MPa, which was 85.8% of the base metal, was obtained at high rotation speed of 8000 rpm and fast welding speed of 1500 mm/min. The tensile strength of the ultra-high speed FSWed butt joints were improved significantly by post-weld artificial aging, with a maximum joint efficiency of 90.4%.

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