Microstructure and Properties of High Strength Steel Weld Metals

2012 ◽  
Author(s):  
J. A. Gianetto ◽  
G. R. Goodall ◽  
W. R. Tyson ◽  
F. Fazeli ◽  
M. A. Quintana ◽  
...  
Keyword(s):  
Weld Metal ◽  
Gas Metal Arc Welding ◽  
Large Diameter ◽  
High Strength Steels ◽  
High Strength ◽  
High Productivity ◽  
Metal Arc Welding ◽  
Wide Range ◽  
Girth Welds ◽  
Welding Processes

With an industry trend towards application of modern high strength steels for construction of large diameter, high pressure pipelines from remote northern regions there is a need to develop high-productivity welding processes to reduce costs and deal with short construction seasons. Achieving the required level of weld metal overmatching together with adequate ductility and good low temperature toughness is another major challenge for joining high strength X80/100 pipes. It is important to develop an improved understanding of weld metal systems that are required for the successful production of high strength pipeline girth welds that are needed for such demanding pipeline construction. In this investigation a range of weld metal (WM) compositions based on (i) C-Mn-Si-Mo, (ii) C-Mn-Si-Ni-Mo-Ti and (iii) C-Mn-Si-Ni-Cr-Mo-Ti was selected for more detailed evaluation of experimental plate welds complemented by specimens simulated by Gleeble® thermal cycling. Five specially-designed experimental plate welds were made with a robotic single torch pulsed gas metal arc welding (GMAW-P) procedures with wire electrodes applicable for joining X100 pipe. The procedures consisted of three initial fill passes deposited at 0.5 kJ/mm and a final deep-fill pass at 1.5 kJ/mm to just fill the narrow-gap joint. An important part of the research focused on development of WM Continuous Cooling Transformation (CCT) diagrams to establish the influence of composition and thermal cycle (cooling time) on formation of fine-scale, predominantly martensite, bainite and acicular ferrite (AF) microstructures. For the relatively wide range of cooling times investigated (Δt800−500 = 2 to 50 s), the lowest-alloyed WM (LA90) exhibited microstructures dominated by bainite with martensite to AF, whereas the highest-alloyed WM (PT02) formed large fractions of martensite with bainite to AF. Weld metal toughness was evaluated using both through-thickness notched 2/3 sub-size Charpy-V-notch (CVN) specimens as well as full-size surface-notched specimens. Post-test metallographic and fractographic examinations of selected fractured specimens were used to correlate WM microstructure and notch toughness.

Thermal Simulation and Its Experimental Verifications for Girth Welds in High-Strength Pipelines

2010 ◽  
Author(s):  
Yaoshan Chen ◽  
Yong-Yi Wang ◽  
Vaidyanath Rajan ◽  
Marie Quintana
Keyword(s):  
Thermal Model ◽  
Gas Metal Arc Welding ◽  
Superposition Principle ◽  
High Strength Steels ◽  
High Strength ◽  
Welding Parameters ◽  
Transfer Model ◽  
Thermal Cycles ◽  
Girth Welds ◽  
Welding Processes

Girth welds in high-strength pipeline constructions are often made with mechanized pulsed gas-metal-arc welding (P-GMAW) process. Welding of the high strength steels poses a number of challenges because of the sensitivity of weld mechanical properties to variations in welding parameters and material properties. In addition to the unique characteristics of narrow groove weld geometry and multiple weld passes, the fabrication of P-GMAW girth welds sometimes also employs alternative welding processes such as dual torch or tandem wire in order to increase pipeline construction productivity. In order to understand the dependency of weld properties on welding processes and their parameters, a transient thermal model for multi-pass girth weld had been proposed and successfully developed. The heat transfer model used the superposition principle of heat sources to handle the welding processes with multiple wires or multiple passes. This paper presents the latest development of this numerical approach and its verification against experimental measurements of thermal cycles from X100 girth welds under different welding conditions. A number of X100 pipe girth welds under different welding conditions were made for the verification purpose. The welding conditions include single torch and dual torch P-GMAW process, 1G and 5G welding. Thermocouples were placed in the heat-affected zone (HAZ) and the weld-pool for the measurements of thermal cycles. The measured thermal cycles and cooling times from 800°C to 500°C were compared to those predicted by the thermal model. Very good agreements between the measured results and the numerical prediction by the thermal model were achieved.

The First L555 (X80) Pipeline in Japan

2012 ◽  
Author(s):  
Yoshiyuki Matsuhiro ◽  
Noritake Oguchi ◽  
Toshio Kurumura ◽  
Masahiko Hamada ◽  
Nobuaki Takahashi ◽  
...  
Keyword(s):  
Gas Metal Arc Welding ◽  
Control Process ◽  
High Strength ◽  
Longitudinal Direction ◽  
Full Scale ◽  
Ground Movement ◽  
Bending Test ◽  
Metal Arc Welding ◽  
S Curve ◽  
Girth Welds

The construction of the first L555(X80) pipeline in Japan was completed in autumn, 2011.In this paper, the overview of the design consideration of the line, technical points for linepipe material and for girth welds are presented. In recent years the use of high strength linepipe has substantially reduced the cost of pipeline installation for the transportation of natural gas. The grades up to L555(X80) have been used worldwide and higher ones, L690(X100) and L830(X120), e.g., are being studied intensively. In the areas with possible ground movement, the active seismic regions, e.g., pipeline is designed to tolerate the anticipated deformation in longitudinal direction. In Japan, where seismic events including liquefaction are not infrequent, the codes for pipeline are generally for the grades up to L450(X65). Tokyo Gas Co. had extensively investigated technical issues for L555(X80) in the region described above and performed many experiments including full-scale burst test, full-scale bending test, FE analysis on the girth weld, etc., when the company concluded the said grade as applicable and decided project-specific requirements for linepipe material and for girth weld. Sumitomo Metals, in charge of pipe manufacturing, to fulfill these requirements, especially the requirement of round-house type stress-strain (S-S) curve to be maintained after being heated by coating operation, which is critical to avoid the concentration of longitudinal deformation, developed and applied specially designed chemical composition and optimized TMCP (Thermo-Machanical Control Process) and supplied linepipe (24″OD,14.5∼18.9mmWT) with sufficient quality. It had also developed and supplied induction bends needed with the same grade. Girth welds were conducted by Sumitomo Metal Pipeline and Piping, Ltd and mechanized GMAW (Gas Metal Arc Welding) was selected to achieve the special requirements, i.e., the strength of weld metal to completely overmatch the pipe avoiding the concentration of longitudinal strain to the girth weld, and the hardness to be max.300HV10 avoiding HSC (Hydrogen Stress Cracking) on this portion. Both of RT (Radiographic Test) and UT (Ultrasonic Test) were carried out to all the girth welds. These were by JIS (Japan Industrial Standards) and the project-specific requirements.

Weld Metal Hydrogen Cracking in Transmission Pipelines Construction

2010 ◽  
Author(s):  
Sheida Sarrafan ◽  
Farshid Malek Ghaini ◽  
Esmaeel Rahimi
Keyword(s):  
Weld Metal ◽  
Construction Projects ◽  
High Strength Steels ◽  
High Strength ◽  
Carbon Equivalent ◽  
Transverse Cracks ◽  
Diffusible Hydrogen ◽  
Hydrogen Cracking ◽  
Girth Welds ◽  
Welding Position

Developments of high strength steels for natural gas pipelines have been in the forefront of steelmaking and rolling technology in the past decades. However, parallel to such developments in steel industry, the welding technology especially with regards to SMAW process which is still widely used in many projects has not evolved accordingly. Decreasing carbon equivalent has shifted the tendency of hydrogen cracking from the HAZ to the weld metal. Hydrogen cracking due to its complex mechanism is affected by a range of interactive parameters. Experience and data gained from field welding of pipeline construction projects indicated that weld metal hydrogen cracking is related to welding position as it occurs more in the 6 o’clock position of pipeline girth welds. In this research an attempt is made to open up the above observation in order to investigate the contributory factors such as welding position and welding progression in terms of diffusible hydrogen and possibly residual stress considerations. It was observed that transverse cracks produced in laboratory condition may not be detected by radiography. But, the higher tendency for cracking at 6 o’clock position was confirmed through bend test. It is shown that more hydrogen can be absorbed by the weld metal in the overhead position. It is shown that welding progression may also have a significant effect on cracking susceptibility and it is proposed that to be due to the way that weld residual stresses are developed. The observations can have an important impact on planning for welding procedure approval regarding prevention of transverse cracking in pipeline girth welds.

Fracture Mechanics of Conventional and Narrow Groove Pulse Current Gas Metal Arc Welds of HSLA Steel

2012 ◽  
Vol 710 ◽  
pp. 451-456
Author(s):  
Ravi Ranjan Kumar ◽  
P. K. Ghosh
Keyword(s):  
Fracture Toughness ◽  
Weld Metal ◽  
Tensile Properties ◽  
Arc Welding ◽  
Hsla Steel ◽  
Gas Metal Arc Welding ◽  
High Strength ◽  
Compact Tension ◽  
Shielded Metal Arc Welding ◽  
Metal Arc Welding

Mechanical and fracture properties of 20MnMoNi55 grade high strength low alloy (HSLA) steel welds have been studied. The weld joints were made using Gas Tungsten Arc Welding (GTAW), Shielded Metal Arc Welding (SMAW) and Pulse Gas Metal Arc Welding (P-GMAW) methods on conventional V-groove (V-Groove) and Narrow groove (NG-13). The base metal and weld metal were characterised in terms of their metallurgical, mechanical and fracture toughness properties by following ASTM procedures. The J-Integral fracture test was carried out using compact tension C(T) specimen for base and weld metal. The fracture toughness and tensile properties of welds have been correlated with microstructure. In conventional V-groove welds prepared by P-GMAW shows the improvement in initiation fracture toughness (JIC) as compared to the weld prepared by SMAW. Similar improvements in tensile properties have also been observed. This is attributed to reduction in co-axial dendrite content due to lower heat input during P-GMAW process as compared to SMAW. In the narrow groove P-GMA weld prepared at f value of 0.15 has shown relative improvement of JIC as compared to that of the weld prepared by SMAW process.

scholarly journals Pulse spray gas metal arc welding of advanced high strength S650MC automotive steel

10.30544/682 ◽  
2021 ◽  
Vol 27 (4) ◽  
pp. 505-517
Author(s):  
Ashok Kumar Srivastava ◽  
Pradip K Patra
Keyword(s):  
Weld Joint ◽  
Heat Input ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
High Strength Steels ◽  
High Strength ◽  
Filler Wire ◽  
Advanced High Strength Steels ◽  
Metal Arc Welding ◽  
The Impact

With an increasing demand for safer and greener vehicles, mild steel and high strength steel are being replaced by much stronger advanced high strength steels of thinner gauges. However, the welding process of advanced high strength steels is not developed at the same pace. The performance of these welded automotive structural components depends largely on the external and internal quality of weldment. Gas metal arc welding (GMAW) is one of the most common methods used in the automotive industry to join car body parts of dissimilar high strength steels. It is also recognized for its versatility and speed. In this work, after a review of GMAW process and issues in welding of advanced high strength steels, a welding experiment is carried out with varying heat input by using spray and pulse-spray transfer GMAW method with filler wires of three different strength levels. The experiment results, including macro-microstructure, mechanical properties, and microhardness of weld samples, are investigated in detail. Very good weldability of S650MC is demonstrated through the weld joint efficiency > 90%; no crack in bending of weld joints, or fracture of tensile test sample within weld joint or heat affected zone (HAZ), or softening of the HAZ. Pulse spray is superior because of thinner HAZ width and finer microstructure on account of lower heat input. The impact of filler wire strength on weldability is insignificant. However, high strength filler wire (ER100SG) may be chosen as per standard welding practice of matching strength.

Mechanical properties and microstructural characteristics of rotating arc-gas metal arc welded carbon steel joints

2021 ◽  
Vol 30 (1) ◽  
pp. 49-58
Author(s):  
Nallasamy Sankar ◽  
Sudersanan Malarvizhi ◽  
Visvalingam Balasubramanian
Keyword(s):  
Mechanical Properties ◽  
Carbon Steel ◽  
Weld Metal ◽  
Gas Metal Arc Welding ◽  
Ferrite Matrix ◽  
Metal Arc Welding ◽  
Rotating Arc ◽  
Steel Joints ◽  
Welding Processes ◽  
Lamellar Pearlite

Abstract The main problem associated with high thickness carbon steel plate's narrow range or “V” groove welding in conventional welding processes is the sagging of the molten pool due to gravity, which in turn leads to defects formation and deteriorates mechanical properties. This problem could be overcome by the rotating arc gas metal arc welding (RA-GMAW) technique. This investigation aims to evaluate mechanical properties and metallurgical characteristics of high thickness IS2062 Gr-B carbon steel joints welded by RA-GMAW technique. The experimental results show that RA-GMAW joint exhibited higher (598 MPa) tensile strength, higher hardness (220 HV) at weld metal region, and lower impact toughness (137 J) than the unwelded base metal. This is due to the presence of fine acicular ferrite and widmanstatten ferrite matrix mixed with fine lamellar pearlite microstructure in the weld metal region.

Welding Properties and Fatigue Resistance of S690QL High Strength Steels

2015 ◽  
Vol 812 ◽  
pp. 29-34 ◽  
Author(s):  
Ádám Dobosy ◽  
János Lukács
Keyword(s):  
Fatigue Resistance ◽  
Welded Joints ◽  
Gas Metal Arc Welding ◽  
Research Work ◽  
Base Material ◽  
High Strength Steels ◽  
High Strength ◽  
Fatigue Tests ◽  
Metal Arc Welding ◽  
Welding Properties

The objective of this article is to present the first results of our research work. In order to determination and comparison of the fatigue resistance, high cycle fatigue tests (HCF) were performed on RUUKKI OPTIM S690QL quenched and tempered high strength steel. In parallel these; welded joints were made on the same steel using gas metal arc welding (GMAW, MIG/MAG) to preparation of the cyclic investigations of the welded joints. In the article, the performance of the welding experiments will be presented; along with the results of the HCF tests executed on the base material and its welded joints. Furthermore, our results will be compared with different literary data.

Hybrid Laser/Gas Metal Arc Welding of High Strength Steel Gas Transmission Pipelines

2008 ◽  
Author(s):  
Ian D. Harris ◽  
Mark I. Norfolk
Keyword(s):  
Fiber Laser ◽  
High Power ◽  
Arc Welding ◽  
Fiber Lasers ◽  
Band System ◽  
Gas Metal Arc Welding ◽  
High Strength ◽  
Travel Speed ◽  
Metal Arc Welding ◽  
Welding Processes

Despite significant investment, one-shot welding and power beam processes have not been very successful in achieving real benefits in pipeline construction. The most promising of the newer and more innovative welding processes is the hybrid Laser/arc welding process (HLAW), which can complete 5G welds, assure weld soundness, material properties, and an acceptable geometric profile. The combination of new lasers and pulsed gas metal arc welding (GMAW-P) power source technologies have led to important innovations in the HLAW process that have been shown to increase the travel speed for successful root pass welding. In particular, high power Yb fiber lasers with high efficiency (25% compared with 3% for a Nd:YAG laser) allow a 10kW laser to be built the size of a refrigerator. This allows for previously unheard of portability and power levels for use outside the laboratory and on the pipeline right-of-way. The objective was to develop and apply an innovative HLAW system for mechanized welding of high strength, high integrity, pipelines and develop 5G welding procedures for X80 and X100 pipe, including mechanical testing to API 1104. The main goal of a cost-matched JIP was to develop a prototype hybrid high power Yb fiber laser and GMAW head based on a commercially available bug and band system (Figure 1). Under the DOT project, the subject of this paper, innovative technologies for pipeline girth welding were developed. External hybrid root pass welding techniques were developed for variations of laser power (4–10 kW) and root face thickness (4–8 mm) as this has the greatest potential to meet existing pipeline integrity requirements and facilitate the use of new high power Yb fiber lasers for high speed HLAW of pipe root passes. Following the integration of the Yb fiber laser and GMAW head onto a commercially available bug and band system (CRC-Evans P450) the system was used to achieve full penetration welds with a 4 mm root at a travel speed of 2.3 m/min. The root welds were made in a “double down” configuration using laser powers up to 10kW and travel speeds up to 3 m/min. The final objective of the project is to demonstrate the hybrid LBW/GMAW system under field conditions.

Structures and Properties of X80 Pipeline Girth Welds for Different Welding Procedures

2012 ◽  
Author(s):  
Xiaodong He ◽  
Yangqin Liu ◽  
Lixia Zhu ◽  
Ke Tong ◽  
Xiaodong Shao
Keyword(s):  
Tensile Properties ◽  
Welded Joints ◽  
Arc Welding ◽  
Mass Fraction ◽  
Gas Metal Arc Welding ◽  
High Strength ◽  
Single Wire ◽  
Metal Arc Welding ◽  
The Difference ◽  
Girth Welds

The X80 girth welds were produced by solid-wire gas metal arc welding (GMAW) and shield metal arc welding (SMAW) using two welding consumables respectively, which contained different mass fraction of C, Mo and Ni. The tensile properties, notch toughness, hardness, and microstructures of welded joints were evaluated. The results indicate that high strength and good toughness of welded joints can be achieved. But the tensile properties of all weld metal of GMAW and SMAW process were evidently different because of the difference of mass fraction of C, Mo, Ni. The strength reduced slightly in softening zone of HAZ. Using welding consumable which contain higher Mo additions, the microstructure in weld seam and fusion zones were IAF+GB and GB+M respectively. Furthermore, the mechanical properties of X80 pipeline welded by single wire welding and double wire welding respectively have been compared. The double wire welds exhibited lower yield strength but higher toughness compared to the corresponding single wire welds.

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