Microstructure Transformation and Mechanical Properties of X80 Large Diameter Thick Wall Induction Heating Bend for Low Temperature Service

2020 ◽  
Author(s):  
Yu Liu ◽  
Zongbin You ◽  
Lijun Yan
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Weld Metal ◽  
Acicular Ferrite ◽  
Base Material ◽  
Welding Process ◽  
Seam Weld ◽  
Bent Pipe ◽  
Low Temperature Toughness ◽  
Submerged Arc

Abstract For the requirement of pipeline station construction project, Grade X80 Longitudinally Submerged Arc Welded (LSAW) induction bend pipe 1422 mm in diameter and wall thickness greater than 25 mm have been developed for pipeline station service applications at −45 °C. The mother pipe of the bends was welded by Ni-Cr-Cu-Mo-Nb-V micro-alloyed Thermo Mechanical Control Process (TMCP) steel plates. After the heat cycle of the bent pipe manufacturing, the microstructure of the base material of the bent pipe consisted of lath bainite ferrite (LBF) and granular bainite (GB). Therefore, it can obtain high strength and excellent low temperature toughness, which can meet the requirements of the project. On the other hand, the welding of the longitudinal seam-welds of the bend mother pipe uses a typical multi-wire two-pass submerged arc welding (SAW) process, which has a large amount of welding heat input. This results in a coarse columnar weld structure with a large amount of fine acicular ferrite so that the seam weld still has a good low temperature impact toughness. However, after the thermal cycling of the bend, the acicular ferrite in the microstructure of the weld metal was greatly reduced, and the grain size was unevenly distributed, which caused the low temperature toughness of the weld metal to deteriorate significantly. In order to solve this problem, the Gleeble3500 thermal simulation test machine was used to test the phase transition critical point Ac3 of the base material and the seam weld metal of the mother pipe. In order to optimize the induction bend process parameters, the influence of heating temperature, cooling rate and tempering temperature on microstructure and mechanical properties were examined. In addition, on the basis of the existing welding process, the welding wire and flux for pipe-making seam-welding were improved, and the pipe-making welding process of the bent mother pipe was improved.

Full Scale Reeling Simulation Test of X65 HFW Linepipe

2014 ◽  
Author(s):  
Teruki Sadasue ◽  
Satoshi Igi ◽  
Hisakazu Tajika ◽  
Kenji Oi ◽  
Satoru Yabumoto
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Plastic Strain ◽  
Base Material ◽  
Full Scale ◽  
Simulation Test ◽  
Offshore Pipelines ◽  
Strain Concentration ◽  
Seam Weld ◽  
Low Temperature Toughness

Reel-lay method is widely recognized cost effective installation process for offshore pipelines. In the process of reel-lay, cyclic plastic strain is expected at pipelines due to reeling, unreeling, aligning and straightening. In order to maintain integrity of pipelines subjected to large bending deformation it is necessary to understand the bending deformability and change in mechanical properties of pipelines. Advanced HFW (High Frequency electric resistance Welded) linepipe “MightySeam®” has superior low temperature toughness at seam weld and base material and has some advantages in application to offshore pipelines from a viewpoint of change in toughness due to pre-straining, coatings and long time exposure. In this paper full scale reeling simulation tests of X65 HFW linepipe were conducted in order to study bending deformability and the change in mechanical properties. The tests were performed by bending pipe alternately to reeling former and straitening former with different radii. Girth welding were applied to test pipes in order to investigate effect of strain concentration around girth weld by strength mismatch or weld reinforcement. Small scale reeling simulation tests with/without aging were also conducted and the results were compared to those of full scale reeling simulation tests. In full scale reeling simulation test, some strain concentration arose around girth weld by strength mismatch and local contact of weld reinforcement to former. Some ovalizations were advanced during tests, however local buckling could not be recognized throughout pipes even if strain concentration occur around girth welds. Tensile properties were changed proportional to last introduced plastic strain as a result of Bauschinger effect and work hardening at strain history. Low temperature toughness of base material and seam weld did not change significantly by pre-straining or aging.

Recommendations for Submerged Arc Spiral Welding With Optimized CTOD Properties

2018 ◽  
Author(s):  
Martin Liebeherr ◽  
Özlem E. Güngör ◽  
Nuria Sanchez ◽  
Hervé Luccioni ◽  
Nenad Ilic
Keyword(s):  
Weld Metal ◽  
Base Material ◽  
Welding Process ◽  
Experimental Program ◽  
Welding Parameters ◽  
Pipe Production ◽  
Filler Wire ◽  
Crack Tip Opening Displacement ◽  
Wide Range ◽  
Submerged Arc

Many pipe mills may not be familiar with a Crack Tip Opening Displacement (CTOD) requirement on the pipe seam weld, nor will they find easily relevant information in open literature. Influencing — and certainly not independent — factors are: welding parameters, base material and consumable selection. Out of these, the welding parameters such as heat input and cooling rate cannot be varied over a wide range during the pipe production, which means that the leverage is rather limited at the given welding process. The properties of the heat affected zone will be mainly affected by the base material, while the properties of the weld metal will be affected by both, base material and filler wire selection. In particular with respect to the weld metal properties it will be difficult to obtain general quantitative information. For example, a welding consumable supplier will readily provide the properties of the filler wires but would be unable to predict the changes caused by the dilution from any base material in the weld pool and specific welding procedures that may have been used. To support the pipe mills in the selection of the consumables for submerged arc welding, an experimental program was launched with the aim to provide recommendations on how to optimize CTOD toughness of the spiral weld seam. For this, a large number of welds were produced on 20 mm thick X70 coil samples, with eight different filler wire combinations, using a 2-wire (tandem) set-up for both the inside and outside weld. Welding parameters were kept constant. The welding program was applied to two different X70 steels to determine a potential influence of the micro-alloying elements, particularly Nb. The results show clearly that a careful consumable selection is required for obtaining acceptable CTOD toughness in the weld metal. Ni-Mo and Ti-B additions to the weld metal are found to be beneficial with both steel concepts. Mo addition alone both to the ID and OD welds was clearly not a suitable selection.

The Influence of Diffusible Hydrogen in Weld Metal and Moisture Content Levels in Flux Related With Weld Metal Mechanical Properties in Submerged Arc Welding Process for Line Pipe Manufacturing

2015 ◽  
Author(s):  
Gautam Chauhan ◽  
Piyush Thakor ◽  
Satyanarayana Samavedam ◽  
Ramakrishnan Mannarsamy ◽  
Ashif Sheikh ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Weld Metal ◽  
Hydrogen Content ◽  
Welding Process ◽  
Diffusible Hydrogen ◽  
Line Pipe ◽  
Arc Welding Process ◽  
Submerged Arc ◽  
Pipe Manufacturing

The mechanical properties of welding material is correlative with the diffusible hydrogen content in weld metal and level of moisture content in flux. Minitab16program to predict mechanical properties correlated to diffusible hydrogen content in weld metal and level of moisture content in flux, such as yield strength, tensile strength, elongation and average Charpy impact toughness of welding material is established by using submerged arc welding process in line pipe manufacturing. The present paper aims to experiment and investigate the line pipe SAW Flux used for offshore/onshore applications. Flux moisture content has been studied under Karl Fischer Coulometer method. Subsequently, flux was then used to make weld to analysis for ‘diffusible hydrogen content in weld metal’ through mercury displacement method. This detailed study envisages and explains the correlations between the mechanical properties and micro structures of weldments. Evaluating the variance of moisture level in flux and diffusible hydrogen content in weld metal proves the advantage of restricting the moisture content along with good practices to accomplish better weld quality.

scholarly journals Microstructure features and formation mechanism in a newly developed electroslag welding

2021 ◽  
Author(s):  
Tomonori Kakizaki ◽  
Shodai Koga ◽  
Hajime Yamamoto ◽  
Yoshiki Mikami ◽  
Kazuhiro Ito ◽  
...  
Keyword(s):  
Low Temperature ◽  
Weld Metal ◽  
Heat Input ◽  
Acicular Ferrite ◽  
Charpy Impact ◽  
Electroslag Welding ◽  
Weld Metals ◽  
Columnar Grains ◽  
Cooling Speed ◽  
Low Temperature Toughness

AbstractElectroslag welding (ESW) is known to show higher heat input than electrogas welding (EGW), resulting in poor low-temperature toughness. However, a newly developed ESW (dev. ESW) method using low-resistivity slag bath exhibited excellent low-temperature toughness as a result of lower effective heat input than conventional EGW, as demonstrated by the faster cooling rates measured in weld metals and estimated using finite element method analyses. This led to much shallower molten pool in the dev. ESW, resulting in much finer columnar grains and thinner centerline axial grains. High cooling speed in the dev. ESW method appeared to contribute to increased acicular ferrite proportion. The uniform microstructure with large acicular ferrite proportion and small number of inclusions in the weld metal permitted the dev. ESW weld metal to possess little variation in Charpy impact energy across the center of weld metal.

A High Notch Toughness Agglomerated Flux for Submerged Arc Welding of Pipeline Steel

2006 ◽  
Vol 306-308 ◽  
pp. 405-410 ◽  
Author(s):  
De Liang Ren ◽  
Bo Liao ◽  
Changling Xu ◽  
Lianhai Hu ◽  
Fu Ren Xiao
Keyword(s):  
Low Temperature ◽  
Weld Metal ◽  
Arc Welding ◽  
High Speed ◽  
Uniform Design ◽  
Welding Process ◽  
Submerged Arc Welding ◽  
Notch Toughness ◽  
Technical Specifications ◽  
Submerged Arc

By using the mathematical uniform design, a new agglomerated flux for high speed and multi-arc submerged arc welding (SAW) has been developed in this paper, which performs excellently in welding process, and the effects of flux composition on the welding characteristics is analyzed as well. The mechanical tests show that the weld metal obtained in SAW with this flux exhibits high toughness at low temperature, and the other mechanical properties of the weld metal also satisfy the technical specifications for the West to East Pipeline Project in China. The microstructures of the weld metal are also examined. Both optical and TEM microphotoes demonstrate that the weld consists mainly of small-sized and uniformly distributed acicular ferrite. These microstructures can effectively prevent the initiation and propagation of micro cracks, resulting in high notch toughness of the weld metal at low temperature.

Establishment of Cold Wire Addition Technology® in Multiwire Submerged Arc Welding for Line Pipe Manufacturing to Improve the Weldment Quality

2015 ◽  
Author(s):  
Ramakrishnan Mannarsamy ◽  
S. K. Shrivastava ◽  
Piyush Thakor ◽  
Gautam Chauhan ◽  
S. K. Joshi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Arc Welding ◽  
Welding Process ◽  
High Strength ◽  
Submerged Arc Welding ◽  
Line Pipe ◽  
Cold Wire ◽  
Welding Procedure ◽  
Submerged Arc

For achieving high productivity multiple wire submerged arc welding such as tandem wire, three wires and five wires submerged arc welding was introduced in recent past years. Due to adding of additional wires in a pipe mill faced process difficulties such as controlling the current supply to each wire and further challenges for consumable design in order to give effective slag characteristics and bead shape control at these higher welding speeds and heat inputs. To gain maximum productivity, welding speed must be as fast as possible (in excess of 2 m/min) consistent with reliable high speed wire feeding and the characteristics of the SAW flux considering these factors in determining the balance of heat input, penetration, bead shape, dilution, weld metal chemistry and mechanical properties such as toughness. Steels containing high strength low alloying elements like Manganese, Molybdenum, Titanium and boron have favorable physical properties such as higher subzero toughness, resistance to improve the mechanical properties because of which there is substantial saving in the material. High strength low alloy steels materials are utilized in offshore and onshore at critical services. However, such benefits can be exploited provided these steels can be welded with appropriate development of welding process such as cold wire addition® in multi wires with process controller using WINCC programmer, Z5 version to give better weldments, which will not compromise the integrity, and operating condition. To obtain higher productivity and quality, it is necessary to develop a welding procedure for butt joint of line pipe steels. This paper describes the recent work carried out by Welspun, in this regard to establish the welding procedure using GMAW and submerged arc welding process and evaluation of mechanical properties. Macro and micro structural analysis were also made to characterize the weld metal properties.

scholarly journals OPTIMALISASI KOMPOSISI KANDUNGAN MN PADA FILLER UNTUK MENDAPATKAN KETANGGUHAN DAN KEKERASAN

2012 ◽  
Vol 12 (1) ◽  
pp. 41
Author(s):  
NUR SUBEKI
Keyword(s):  
Weld Metal ◽  
Acicular Ferrite ◽  
High Reliability ◽  
Welding Process ◽  
Welded Steel ◽  
Steel Pipes ◽  
Weld Metals ◽  
Ferrite Structure ◽  
Relationship Of ◽  
Submerged Arc

Submerged Arc Welding (SAW) is a welding process used for fabrication of pipes, for example spiral welded pipes. Thetechnique can be operated automatically and has a high reliability in many various welding applications. Some factorsaffecting the strength of weld metals are heat input, current, and chemical composition of filler, flux, and base metal.The present investigation aims to study microstructure-hardness relationship of submerged arc spiral welded steel pipes. Material used in this experiment was API 5L X-52 and API 5L X-60 for spiral welded steel pipes. Welding was carried out using voltage of 35 volt, welding speed of 13,67 mm/s whereas composition Mn on the flux was varied, 1.7; 1.4; 1.4 with Mo and 1.09. Microstructure and hardness were conducted on base metal, weld metal and heat affected zone (HAZ). Results show that, an increase in composition of Mn could be increases the amount of acicular ferrite structure in weld metal. The hardness and thougness number is increase correlated with increase number of Mn, but for the composition Mn as 1,7, the number of acicular ferrite is decrease, the consequence of hardness number is decrease.

scholarly journals Influence of the Heat Input on the Dendritic Solidification Structure and the Mechanical Properties of 2.25Cr-1Mo-0.25V Submerged-Arc Weld Metal

2021 ◽  
Author(s):  
Hannah Schönmaier ◽  
Ronny Krein ◽  
Martin Schmitz-Niederau ◽  
Ronald Schnitzer
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Heat Input ◽  
Stress Rupture ◽  
Pressure Vessels ◽  
Rupture Time ◽  
Solidification Structure ◽  
Welding Parameters ◽  
Austenite Grain Size ◽  
Submerged Arc

AbstractThe alloy 2.25Cr-1Mo-0.25V is commonly used for heavy wall pressure vessels in the petrochemical industry, such as hydrogen reactors. As these reactors are operated at elevated temperatures and high pressures, the 2.25Cr-1Mo-0.25V welding consumables require a beneficial combination of strength and toughness as well as enhanced creep properties. The mechanical properties are known to be influenced by several welding parameters. This study deals with the influence of the heat input during submerged-arc welding (SAW) on the solidification structure and mechanical properties of 2.25Cr-1Mo-0.25V multilayer metal. The heat input was found to increase the primary and secondary dendrite spacing as well as the bainitic and prior austenite grain size of the weld metal. Furthermore, it was determined that a higher heat input during SAW causes an increase in the stress rupture time and a decrease in Charpy impact energy. This is assumed to be linked to a lower number of weld layers, and therefore, a decreased amount of fine grained reheated zone if the multilayer weld metal is fabricated with higher heat input. In contrast to the stress rupture time and the toughness, the weld metal’s strength, ductility and macro-hardness remain nearly unaffected by changes of the heat input.

scholarly journals A Study on Rotary Friction Welding of Titanium Alloy (Ti6Al4V)

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Ho Thi My Nu ◽  
Truyen The Le ◽  
Luu Phuong Minh ◽  
Nguyen Huu Loc
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloys ◽  
Friction Welding ◽  
Base Material ◽  
Welding Process ◽  
High Strength ◽  
Fusion Welding ◽  
Experimental Results ◽  
Thermomechanical Model ◽  
Rotary Friction Welding

The selection of high-strength titanium alloys has an important role in increasing the performance of aerospace structures. Fabricated structures have a specific role in reducing the cost of these structures. However, conventional fusion welding of high-strength titanium alloys is generally conducive to poor mechanical properties. Friction welding is a potential method for intensifying the mechanical properties of suitable geometry components. In this paper, the rotary friction welding (RFW) method is used to study the feasibility of producing similar metal joints of high-strength titanium alloys. To predict the upset and temperature and identify the safe and suitable range of parameters, a thermomechanical model was developed. The upset predicted by the finite element simulations was compared with the upset obtained by the experimental results. The numerical results are consistent with the experimental results. Particularly, high upset rates due to generated power density and forging pressure overload that occurred during the welding process were investigated. The performances of the welded joints are evaluated by conducting microstructure studies and Vickers hardness at the joints. The titanium rotary friction welds achieve a higher tensile strength than the base material.

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