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Drammen, Norway

Moe P.T.,Norwegian University of Science and Technology | Moe P.T.,AMR Engineering AS | Salberg B.,AMR Engineering AS | Rabben K.,AMR Engineering AS | And 4 more authors.
International Journal of Material Forming | Year: 2010

Shielded Active Gas Forge Welding is a fully automatic high speed welding process for metals. It was invented in the early 1980s, but has since then been significantly improved and commercialized for mainly casing and pipeline applications for the oil and gas industry. The method consists of three main steps: (1) localised heating of the mating surfaces, (2) forging and joining of the mating surfaces and (3) heat treatment of the weld. An entire welding cycle can be completed in two minutes, independent of dimension. The method has been used for welding a great range of alloys, and it produces a weld with properties similar to those of the base material. © 2010 Springer-Verlag France. Source


Palanisamy V.,Norwegian University of Science and Technology | Solberg J.K.,Norwegian University of Science and Technology | Salberg B.,AMR Engineering AS | Moe P.T.,Norwegian University of Science and Technology
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2012

The continuous development of line pipe and casing grade steels should be complemented by development of more effective welding methods. A special high temperature high speed forge welding technique called Shielded Active Gas Forge Welding (SAG-FW) has been developed to weld steel pipes for a range of applications. This article focuses on the microstructure development at different welding conditions in L80 steel with 0.25%C. Specimens with dimensions 100 mm x 11 mm x 6 mm were extracted from the wall of a large diameter L80 pipe. A SMITWELD thermal simulator was used to simulate heat treatment conditions using electrical resistance heating. The specimens were heated to peak temperatures ranging from 600°C to 1350°C within 10 s and subsequently quenched to 50°C at a constant rate of 60 °C/s to simulate the heat-affected zone conditions for the real SAG-FW process. Martensite with small fractions of bainite was observed for higher peak temperatures. Mixed microstructures were observed in the specimens heated in the intercritical temperature range. Microstructures and phase fractions developed after heating to different peak temperatures have been analyzed by optical microscopy and scanning electron microscopy. Charpy V-notch tests and Vickers microhardness measurements have been carried out for the weld simulated specimens. The observed toughness values, hardness values, microstructures and phase fractions have been correlated to the respective weld simulation parameters. Copyright © 2012 by ASME. Source


Vinothkumar P.,Norwegian University of Science and Technology | Ganesan S.M.,Norwegian University of Science and Technology | Solberg J.K.,Norwegian University of Science and Technology | Salberg B.,AMR Engineering AS | Moe P.T.,Norwegian University of Science and Technology
Advanced Materials Research | Year: 2012

Shielded Active Gas Forge Welding (SAG-FW) is a solid state bonding process in which two mating surfaces are locally heated and forged together to form a bond. SAG-FW has so far mainly been used to join materials for pipe-line and casing applications. The present study has been conducted on an API 5CT L80 grade material in a prototype forge welding machine. Small-scale pipe specimens have been extracted from the wall of the production casing. The SAG-FW process is completed within a few seconds of heating and forging followed by controlled cooling. The microstructure of the weld is determined by the processing parameters. In this paper, microstructure results for SAG-FW processed L80 material have been obtained for a range of cooling rates and systematically compared with microhardness values. Microstructure observations at different regions of the weld have been made. Faster heating rate and controlled cooling resulted in a mixture of non equilibrium microstructures, but satisfactory mechanical properties have been obtained for optimized processing parameters. © (2012) Trans Tech Publications, Switzerland. Source


Liu J.,AMR Engineering AS | Marimuthu G.S.,Norwegian University of Science and Technology | Moe P.T.,Norwegian University of Science and Technology
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2013

Shielded Active Gas Forge Welding is a high speed welding method for joining inter alia steel pipeline and casing. The process consists of a heating step, in which the bevels of the sections to be joined are heated locally to temperatures exceeding 1000 °C, and a subsequent forging step in which joining takes place by the application of a high axial force. In order to make possible cost-effective welding qualification and research a small scale forge welding machine has been developed. Down-scaling of the forge welding process should be carefully assessed in order to establish the limits of the process. In this paper two aspects of the forge welding process have been studied in detail by the use of finite element modeling and experiments: a) coupled thermal and electro-magnetic modeling of heating and b) coupled thermo-mechanical modeling of forging. Special attention is given to the study of the limits of buckling of the pipe wall during forging. A high thermal gradient in the axial direction in the pipe wall facilitates local plastic deformation during forging and proper fusion of welds. For elongated temperature fields buckling is more likely to occur since the effective stiffness of the wall section is reduced. The limits of buckling depend on the wall thickness and diameter of section to be joined. While the forge welding process works very well for virtually all types of full scale pipeline and casing sections, buckling has been observed when joining very thin-walled small scale pipes. For welding of stainless steel small scale pipes local heating proves challenging. These challenges may be overcome by innovative welding machine design, and by carefully assessing welding process limitations. Certain physical limitations must still be considered. Copyright © 2013 by ASME. Source


Marimuthu G.S.,Norwegian University of Science and Technology | Moe P.T.,Norwegian University of Science and Technology | Salberg B.,AMR Engineering AS | Audestad J.I.,AMR Engineering AS
Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE | Year: 2012

A state-of-the-art small-scale solid state forge welding machine has been fabricated for checking weldability by Shielded Active Gas Forge Welding (SAG-FW) of tubular products applicable predominantly for, but not limited to offshore Industries. Effective, fast and inexpensive welding and testing of joints make this small-scale method suitable for evaluating weldability of a material before starting regular qualification and fabrication in a full-scale welding machine normally located in spool base or offshore. The small-scale machine provides a complete package for pre-qualification studies, including assessment of welding conditions, material flow behavior, heat treatment options. However, there are considerable challenges relating to application of international standards of testing as well as interpretation and use of results in the context of large-scale welding. In this paper results from small-scale welding and weld characterization of an API 5L X65 quality are presented. First, a detailed test plan for analyzing the weld is outlined. This procedure is subsequently applied for checking the welds to be produced in the full-scale machine. Short-comings in using the small-scale process as well as the possible remedies are discussed in detail. Copyright © 2012 by ASME. Source

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