Influence of Alloying Elements on the Toughness in the HAZ of DSAW-Welded Large-Diameter Linepipes

2012 ◽  
Author(s):  
Charles Stallybrass ◽  
Olga Dmitrieva ◽  
Andreas Liessem ◽  
Jens Schröder
Keyword(s):  
Arc Welding ◽  
Large Diameter ◽  
Base Material ◽  
Processing Parameters ◽  
Submerged Arc Welding ◽  
Alloying Elements ◽  
Fusion Line ◽  
Steel Composition ◽  
Submerged Arc ◽  
Haz Toughness

There is a strong interest worldwide to transport large gas volumes from remote areas and hostile environments to the market. Pipe producers are therefore faced with increasingly demanding requirements both with regard to the toughness of the base material and the heat-affected zone. The toughness of the base material depends primarily on the steel composition and the TM processing conditions. Impressive levels of toughness in the base material were achieved by extensive alloy and process development over the past decades. These were realised by balancing the steel composition and processing parameters to give an optimum microstructure with a low grain size and homogeneous distribution of phases. During double submerged arc welding (DSAW) in the production of large-diameter linepipes, the heat-affected zone (HAZ) undergoes severe changes in the microstructure that include grain coarsening by about one order of magnitude and phase transformation during cooling and intercritical reheating. These have a negative impact on the toughness close to the fusion line. The higher austenite grain size close to the fusion line leads to a coarser structure after the phase transformation with larger carbon-rich M/A-phase particles than are typically observed in the base material in the as-rolled condition. This causes a drop of the toughness close to the fusion line compared to the base material. Classically, the carbon equivalent is an empirical measure for the weldability of steels and is known to correlate with the maximum hardness. However, its purpose is not to reflect the effect of individual alloying elements on the HAZ-toughness. The present paper addresses the relationship between base material composition and the HAZ-toughness of linepipe steels. An experimental investigation was carried out at EUROPIPE GmbH in cooperation with Salzgitter Mannesmann Forschung GmbH in which the chemical composition of laboratory heats was varied systematically. These heats were thermomechanically rolled to a wall thickness of 30 mm and subsequently used for submerged arc welding trials. The processing parameters during rolling and welding were held constant in the trials in order to ensure that the effect of the alloying elements could be isolated. The fusion line toughness was tested at −30°C and the microstructure was investigated by high-resolution scanning electron microscopy. This was complemented by microstructure investigations in the HAZ of large-diameter pipe material between the X65 and X80 strength levels. It was found that the influence of alloying elements on the HAZ-toughness is only reflected to some degree by the commonly used carbon equivalents, especially at similar strength levels. The results of the investigation were used for optimisation of the HAZ-toughness in production.

Mechanical Behaviour of Welded Joints Achieved by Multi-Wire Submerged Arc Welding

2017 ◽  
Vol 1143 ◽  
pp. 52-57
Author(s):  
Elena Scutelnicu ◽  
Carmen Catalina Rusu ◽  
Bogdan Georgescu ◽  
Octavian Mircea ◽  
Melat Bormambet
Keyword(s):  
Mechanical Behaviour ◽  
Welded Joints ◽  
Arc Welding ◽  
Base Material ◽  
High Strength ◽  
Submerged Arc Welding ◽  
Steel Plates ◽  
Wire Saw ◽  
Api 5L X70 Steel ◽  
Submerged Arc

The paper addresses the development of advanced welding technologies with two and three solid wires for joining of HSLA API-5l X70 (High-strength low-alloy) steel plates with thickness of 19.1 mm. The experiments were performed using a multi-wire Submerged Arc Welding (SAW) system that was developed for welding of steels with solid, tubular and cold wires, in different combinations. The main goal of the research was to assess the mechanical performances of the welded joints achieved by multi-wire SAW technology and then to compare them with the single wire variant, as reference system. The welded samples were firstly subjected to NDT control by examinations with liquid penetrant, magnetic particle, ultrasonic and gamma radiation, with the aim of detecting the specimens with flaws and afterwards to reconsider and redesign the corresponding Welding Procedure Specifications (WPS). The defect-free welded samples were subjected to tensile, Charpy V-notch impact and bending testing in order to analyse and report the mechanical behaviour of API-5l X70 steel during multi-wire SAW process. The experimental results were processed and comparatively discussed. The challenge of the investigation was to find the appropriate welding technology which responds simultaneously to the criteria of quality and productivity. Further research on metallurgical behaviour of the base material will be developed, in order to conclude the complete image of the SAW process effects and to understand how the multi-wire technologies affect the mechanical and metallurgical characteristics of the API-5L X70 steel used in pipelines fabrication.

Railway Vehicle Wheel Restoration by Submerged Arc Welding and Its Characterization

Sci ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 25
Author(s):  
Byeong-Choo Coo ◽  
Young-Jin Lee
Keyword(s):  
Arc Welding ◽  
Stress Measurement ◽  
Base Material ◽  
Diffraction Method ◽  
Submerged Arc Welding ◽  
Structural Safety ◽  
Railway Vehicle ◽  
Wear Depth ◽  
Minimum Thickness ◽  
Submerged Arc

When a railway vehicle moves on a curved rail, sliding contact occurs between the rail head side and wheel flange, which wears the wheel flange down. The thinned flange needs to be restored above the required minimum thickness for structural safety. In this study, a new process and welding wire for restoring worn-out railway wheels by submerged arc welding was developed. To characterize the properties of the restored wheel, dilatometric analysis of phase transformation, SEM/EDX analyses, hardness measurement, and residual stress measurement using the X-ray diffraction method were performed. Finally, wear tests with full-size wheel/rail specimens were carried out. It was confirmed that the weld metal was composed of bainitic microstructures as intended, and welding defects were not observed. The wear amount of the restored wheel was greater than that of the base material, but it was less than half of the wear depth of the weld-repaired wheel with ferritic–pearlitic microstructures. The developed process seems applicable to industry.

Numerical Analysis of Microstructure and Residual Stress in the Weld Zone of Multiwire Submerged Arc Welding

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Enlin Yu ◽  
Yi Han ◽  
Haixiang Xiao ◽  
Ying Gao
Keyword(s):  
Residual Stress ◽  
Temperature Measurement ◽  
Arc Welding ◽  
Large Diameter ◽  
Weld Zone ◽  
Submerged Arc Welding ◽  
Welding Parameters ◽  
Welding Quality ◽  
Welding Temperature ◽  
Submerged Arc

As oil and gas pipelines develop toward large throughput and high pressure, more and more attention has been paid to welding quality of oil pipelines. Submerged arc welding is widely applied in manufacturing of large-diameter welded pipes, and the welding quality has an impact on pipeline safety. With a multiwire submerged arc welding test platform and real-time temperature measurement system, temperature measurement has been done for multiwire submerged arc welding process with and without flux coverage, respectively. As a result, thermal cycling curves in both cases have been obtained, and convection and radiation coefficients of flux-covered X80 pipeline steel in air-cooled environment have been corrected. By using sysweld software, a finite-element computational model was set up for microstructure and residual stress in the weld zone of multiwire longitudinal submerged arc welding. Comparative experiment has been done to obtain welding temperature field with relatively high accuracy. Calculation and analysis of residual stress versus preheat residual stress decreased with increasing preheat temperature up to 100 °C, meanwhile content of bainite in microstructure fell, facilitating reduction in residual stress to some extent. This study provides quantitative reference for further optimization of welding parameters and improvement in weld mechanical properties.

Microstructure and Performance of Fe-Based Composite Clad Layer Fabricateded by Submerged-Arc Welding Added Alloy Powder

2011 ◽  
Vol 704-705 ◽  
pp. 752-757
Author(s):  
Li Mei Wang ◽  
Jun Bo Liu ◽  
Chi Yuan
Keyword(s):  
Weight Loss ◽  
Arc Welding ◽  
Room Temperature ◽  
Base Material ◽  
Welding Process ◽  
Submerged Arc Welding ◽  
Mixed Powder ◽  
Q235 Steel ◽  
Clad Layer ◽  
Submerged Arc

TiC particle reinforced Fe-based composite clad layer were in situ synthesized on surface of Q235 steel by Submerged arc Welding of the mixed powder of ferrotitanium, iron, chromium, nickel and colloidal graphite, etc. Microstructure of the clad layer were observed by scanning electron microscope （SEM） and Energy Disperse Spectroscopy (EDS). Wear resistance of the clad layer was tested on wear tester at room temperature compared with the base material Q235 steel. Microhardness of the clad layer was measured by microhardness tester. Results indicated that the fine TiC particles were formed by Submerged-arc Welding process, and the the TiC particles were dispersed in the matrix. The size of TiC particles was less than 2 μm. The microstructure of cladding layer consisted of TiC particles, martensite and austenite. The average microhardness of clad layer was HV0.2601, which was about 3 times as high as the based metal Q235. On the conditions of same wear and room temperature, the weight loss of the base material Q235 is 10-15 times as much as the composite clad layer. The weight loss increase of the clad layer has a little change with the increase of load and the change of load is not sensitive to the weight loss of the clad layer. The clad layer has good load characteristics.

Prediction of Toughness through Evaluation of Alloying Elements Distribution Pattern at Heat-Affected Zone in Submerged-Arc Welding Process of API X70 Steel

2013 ◽  
Vol 467 ◽  
pp. 35-40
Author(s):  
Majid Sharifi ◽  
Najmoddin Arab ◽  
Gholamreza Khalaj
Keyword(s):  
Arc Welding ◽  
Boron Content ◽  
Welding Process ◽  
Alloying Elements ◽  
Welding Seam ◽  
Three Samples ◽  
Copper Manganese ◽  
Arc Welding Process ◽  
Submerged Arc ◽  
Haz Toughness

Six 56" × 19.8 mm, API X70 PSL2 pipes were produced from three different plate suppliers and then three samples in pipe transverse direction and perpendicular to welding seam were taken out from welding area of each supplier. Sampling carried out from weld metal, HAZ and base metal of each sample, then all 27 prepared samples were analyzed. Afterwards the amounts of 14 alloying elements were considered. The results showed that content of Carbon, Sulfur, Boron, Phosphorous, Copper, Manganese, Aluminum, Titanium and Molybdenum have been increased in the HAZ and Silicon, Nickel, Chrome, Vanadium and Niobium decreased. So it is predicted that an increase in Carbon, Aluminum, Phosphorous, Sulfur and Boron content, also a decrease in Silicon, Chrome and Nickel will cause a drop in the HAZ toughness and an increase in Titanium, Manganese, Copper and Molybdenum content, also decrease in Vanadium and Niobium will cause a rise in HAZ toughness.

Effects of Simulation Parameters on Springback in Air Bending of JCO Forming

2014 ◽  
Vol 623 ◽  
pp. 117-120 ◽  
Author(s):  
Li Feng Fan ◽  
Ying Gao ◽  
Jia Xin Yan ◽  
Jian Bin Yun
Keyword(s):  
Finite Element ◽  
Arc Welding ◽  
Large Diameter ◽  
Submerged Arc Welding ◽  
Forming Process ◽  
Air Bending ◽  
Welding Pipe ◽  
X80 Steel ◽  
Simulation Parameters ◽  
Submerged Arc

JCO forming is one of manufacture mode widely used in production of large diameter submerged-arc welding pipes, in which JCO forming process is progressive multi-step air bending. In order to improve JCO forming quality, it is necessary to predict springback of air bending. In this paper, air bending is simulated using finite element method, but simulation parameters directly affected prediction precision. So, taking the air bending of X80 steel Φ1219mm×22mm×12000mm welding pipe for instance, the air bending is simulated by finite element (FE) code ABAQUS. The effects of simulation parameters on springback is discussed. Thus, the results of research provides a basis to improve prediction precision of springback in air bending of JCO forming.

scholarly journals Railway Vehicle Wheel Restoration by Submerged Arc Welding and Its Characterization

Sci ◽  
2019 ◽  
Vol 1 (2) ◽  
pp. 52
Author(s):  
Byeong-Choo Coo ◽  
Young-Jin Lee
Keyword(s):  
Arc Welding ◽  
Stress Measurement ◽  
Base Material ◽  
Diffraction Method ◽  
Submerged Arc Welding ◽  
Structural Safety ◽  
Railway Vehicle ◽  
Wear Depth ◽  
Minimum Thickness ◽  
Submerged Arc

When a railway vehicle moves on a curved rail, sliding contact occurs between the rail head side and wheel flange, which wears the wheel flange down. The thinned flange needs to be restored above the required minimum thickness for structural safety. In this study, a new process and welding wire for restoring worn-out railway wheels by submerged arc welding was developed. To characterize the properties of the restored wheel, dilatometric analysis of phase transformation, SEM/EDX analyses, hardness measurement, and residual stress measurement using the X-ray diffraction method were performed. Finally, wear tests with full-size wheel/rail specimens were carried out. It was confirmed that the weld metal was composed of bainitic microstructures as intended, and welding defects were not observed. The wear amount of the restored wheel was greater than that of the base material, but it was less than half of the wear depth of the weld-repaired wheel with ferritic–pearlitic microstructures. The developed process seems applicable to industry.

scholarly journals Railway Vehicle Wheel Restoration by Submerged Arc Welding and Its Characterization

Sci ◽  
2020 ◽  
Vol 2 (2) ◽  
pp. 33
Author(s):  
Byeong-Choo Coo ◽  
Young-Jin Lee
Keyword(s):  
Arc Welding ◽  
Stress Measurement ◽  
Base Material ◽  
Diffraction Method ◽  
Submerged Arc Welding ◽  
Structural Safety ◽  
Railway Vehicle ◽  
Wear Depth ◽  
Minimum Thickness ◽  
Submerged Arc

When a railway vehicle moves on a curved rail, sliding contact occurs between the rail head side and wheel flange, which wears the wheel flange down. The thinned flange needs to be restored above the required minimum thickness for structural safety. In this study, a new process and welding wire for restoring worn-out railway wheels by submerged arc welding was developed. To characterize the properties of the restored wheel, dilatometric analysis of phase transformation, SEM/EDX analyses, hardness measurement, and residual stress measurement using the X-ray diffraction method were performed. Finally, wear tests with full-size wheel/rail specimens were carried out. It was confirmed that the weld metal was composed of bainitic microstructures as intended, and welding defects were not observed. The wear amount of the restored wheel was greater than that of the base material, but it was less than half of the wear depth of the weld-repaired wheel with ferritic–pearlitic microstructures. The developed process seems applicable to industry.

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