Influence of Multi-layer and Multi-pass TIG Welding Process on the High Strength Weld Metal Microstructure and Toughness

2017 ◽  
Vol 53 (18) ◽  
pp. 106 ◽  
Author(s):  
Xingna PENG
Keyword(s):  
Weld Metal ◽  
Welding Process ◽  
High Strength ◽  
Tig Welding ◽  
Weld Metal Microstructure ◽  
Metal Microstructure

Tensile and Toughness Properties of Pipeline Girth Welds

2006 ◽  
Author(s):  
J. A. Gianetto ◽  
J. T. Bowker ◽  
R. Bouchard ◽  
D. V. Dorling ◽  
D. Horsley
Keyword(s):  
Weld Metal ◽  
Welding Process ◽  
Strain Curve ◽  
High Strength ◽  
Primary Objective ◽  
Stress Strain ◽  
Line Pipe ◽  
Arc Welding Process ◽  
Girth Welds ◽  
Metal Microstructure

The primary objective of this study was to develop a better understanding of all-weld-metal tensile testing using both round and strip tensile specimens in order to establish the variation of weld metal strength with respect to test specimen through-thickness position as well as the location around the circumference of a given girth weld. Results from a series of high strength pipeline girth welds have shown that there can be considerable differences in measured engineering 0.2% offset and 0.5% extension yield strengths using round and strip tensile specimens. To determine whether or not the specimen type influenced the observed stress-strain behaviour a series of tests were conducted on high strength X70, X80 and X100 line pipe steels and two double joint welds produced in X70 linepipe using a double-submerged-arc welding process. These results confirmed that the same form of stress-strain curve is obtained with both round and strip tensile specimens, although with the narrowest strip specimen slightly higher strengths were observed for the X70 and X100 linepipe steels. For the double joint welds the discontinuous stress-strain curves were observed for both the round and modified strip specimens. Tests conducted on the rolled X100 mechanized girth welds established that the round bar tensile specimens exhibited higher strength than the strip specimens. In addition, the trends for the split-strip specimens, which consistently exhibit lower strength for the specimen towards the OD and higher for the mid-thickness positioned specimen has also been confirmed. This further substantiates the through-thickness strength variation that has been observed in other X100 narrow gap welds. A second objective of this study was to provide an evaluation of the weld metal toughness and to characterize the weld metal microstructure for the series of mechanized girth welds examined.

Effect of Ti on the Microstructures and Toughness of TMCP-600 Steel Weld Metals

2013 ◽  
Vol 746 ◽  
pp. 462-466
Author(s):  
Jin Hyun Koh ◽  
Bok Su Jang
Keyword(s):  
Weld Metal ◽  
Impact Energy ◽  
Acicular Ferrite ◽  
Gas Metal Arc Welding ◽  
Control Process ◽  
High Strength ◽  
Weld Metal Microstructure ◽  
Metal Microstructure ◽  
The Impact ◽  
Ti Content

The Ti addition effect on the characteristics of weld metal, such as impact energy, microstructure and nonmetallic inclusions, was investigated to develop a suitable gas metal arc welding wire for the high strength of TMCP (Thermo Mechanical Control Process)-600 steel. The fraction of acicular ferrite which was known to be a favorable weld metal microstructure for toughness was increased with Ti content from 0.002% to 0.025%, The impact energy of weld metal was increased whereas the ductile to brittle transition temperature was decreased with increasing Ti content. The size of nonmetallic inclusion was decreased while the density of inclusions was decreased with increasing Ti content. It was found that Ti content on the weld metal toughness had a plus effect by increasing the fraction of acicular ferrite in the weld metal microstructure.

Microstructural Design for High Strength Steel Welds: The Concept of Duplex Microstructure

2005 ◽  
Author(s):  
Stephen Liu
Keyword(s):  
Weld Metal ◽  
High Strength Steel ◽  
Lath Martensite ◽  
High Strength ◽  
Low Carbon ◽  
Duplex Microstructure ◽  
Weld Metal Microstructure ◽  
Steel Welds ◽  
Metal Microstructure ◽  
Welding Processes

In the past three decades, Colorado School of Mines researchers have investigated flux-related welding processes for pipeline applications and systematically characterized the fundamental behavior of welding fluxes. They also established the relationships between flux ingredients, weld metal microstructure, and weld joint mechanical properties. These studies clarified for high strength steel welds the importance of the bimodal nature of weld metal inclusions, related to weld metal transformations. As strength and toughness levels of the steels continue to increase, new generations of consumables must be developed. Two novel consumables design concepts are being investigated at the CSM. The first one is based on a duplex microstructure consisted of lath martensite and ferrite, and the second is based on low carbon, high alloy martensite.

Double Jointing Technology for Strain-Based Design (SBD) Pipelines

2016 ◽  
Author(s):  
Neerav Verma ◽  
Doug P. Fairchild ◽  
Andrew J. Wasson ◽  
Timothy D. Anderson ◽  
Fredrick F. Noecker
Keyword(s):  
Welding Process ◽  
Cost Savings ◽  
High Strength ◽  
High Productivity ◽  
Weld Properties ◽  
Weld Metal Microstructure ◽  
Welding Consumable ◽  
Metal Microstructure ◽  
Longitudinal Strains ◽  
Submerged Arc

Pipelines may experience significant longitudinal strains when subjected to large ground motions, such as seismic activity, landslides, etc. For these conditions, a strain-based design (SBD) approach can be used. The use of higher strength steels (like X80) for SBD approach can enable significant construction cost savings. Costs can be further reduced through the use of a double jointing process in order to reduce the amount of field welding. However, it is challenging to achieve adequate girth weld properties for SBD scenarios involving higher strength steels by using conventional double jointing processes such as submerged arc welding (SAW). Acicular ferrite interspersed in martensite (AFIM) has been previously identified as an advantageous high strength weld metal microstructure that can be applied in field pipeline construction. In this paper, a double jointing technology for X70+ SBD applications will be discussed. Excellent strength and toughness properties were achieved in double joint welds by using an optimized AFIM welding technology that included a tailored welding consumable wire and a high productivity GMAW-P weld process. Welding procedures are discussed along with mechanical properties achieved. Productivity comparisons suggest that a fully optimized GMAW-P welding process in the 1G-rolled welding position can have productivity comparable to a conventional SAW double jointing process.

Steam Generator Grade P91 Steel Components Creep-Assessment By Test After Extended Service

2021 ◽  
Author(s):  
Ottaviano Grisolia ◽  
Lorenzo Scano ◽  
Francesco Piccini ◽  
Antonietta Lo Conte ◽  
Massimiliano De Agostinis ◽  
...  
Keyword(s):  
High Temperature ◽  
Weld Metal ◽  
Steam Generator ◽  
Microstructure Evolution ◽  
Creep Strength ◽  
Operation Temperature ◽  
Creep Analysis ◽  
Creep Cavitation ◽  
Weld Metal Microstructure ◽  
Metal Microstructure

Abstract Previous study carried out creep analysis for steam generator high-temperature-section two components, outflow tubing and manifold of the superheater harp: they may have been critical because of the long continued service (109,000 hours or twelve years) and loading conditions, including maximum operation temperature (565°C) and applied stress (65 MPa). Metallographic methods by replica had showed no evidence of the creep cavitation in all the positions considered for both tubing and manifold. In particular, they had not found any cavitation or phases affecting creep strength of the material in the base, HAZ and weld metal microstructure. Now, present study carries out investigation for the two components based on the next plant outage outcome, after further 20,000-hours service. Both metallographic methods and hardness measurements’ results would compare with previous ones providing microstructure evolution in the period.

Effect of Environment on Sn Whisker Growth during Welding of Electronic Wires

2015 ◽  
Vol 1110 ◽  
pp. 235-240 ◽  
Author(s):  
Tomomi Sakakida ◽  
Tatsuo Kubouchi ◽  
Yasuyuki Miyano ◽  
Mamoru Takahashi ◽  
Osamu Kamiya
Keyword(s):  
Energy Balance ◽  
Weld Metal ◽  
Whisker Growth ◽  
Weld Zone ◽  
Electrolytic Capacitor ◽  
Sn Whisker ◽  
Sn Whiskers ◽  
Weld Metal Microstructure ◽  
Short Circuits ◽  
Metal Microstructure

In Pb-free Al-Sn welding of electrolytic parts, single-crystal Sn whiskers easily form and can cause problems such as short circuits. Here we report that the growth of Sn whiskers in the weld zone of Al electrolytic condenser leads was suppressed in a vacuum environment. We examined the effect of the environment and weld metal microstructure in order to understand how to control and prevent whisker growth. In vacuum, the weld zone did not form whiskers after more than 100 h, whereas in air, whiskers grew within several hours. This suggests that whiskers require oxygen to form. The growth can be explained by the energy balance between the potential energy of the weld metal and the surface energy of the whisker. Our results will contribute to developing techniques for suppressing the formation of Sn whiskers during the percussion welding of Al electrolytic capacitor leads.

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