scholarly journals COMPUTER ANALYSIS OF THE GMAW AND GMAW-CW WELDING THERMAL CYCLES

2015 ◽  
Vol 14 (2) ◽  
pp. 37
Author(s):  
E. A. M. Mendonça ◽  
E. M. Braga ◽  
A. S. A. Ferreira ◽  
R. R. Maciel ◽  
T. S. Cabral ◽  
...  
Keyword(s):  
Experimental Data ◽  
Heat Input ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Welding Parameters ◽  
Thermal Cycles ◽  
Complex Situation ◽  
Cold Wire ◽  
Metal Arc Welding ◽  
And Behavior

A novel process of welding GMAW-CW (Gas Metal Arc Welding-Cold Wire) had been developed with it resemblance to the GMAW (Gas Metal Arc Welding), the GMAW-CW has an additional wire fed into de weld pool, allowing better deposition rates, while maintaining weld characteristics. However, there is a more complex situation related to the HAZ (Heat Affected Zone) and weld geometry prediction than the GMAW conventional. The welding energy is a high metallurgical important parameter because together with the geometric characteristics of the gasket and the preheat level is decisive in thermal cycles imposed to the material, and therefore in the possible microstructural transformations and behavior of the joint. The behavior of representative curves of thermal cycling reflects important aspects regarding the conditions used in welding. Usually such factors as the type of process, use or non- pre or post- heating, heat input, multipass welding, are able to establish differences in the form of a heat cycle curve. In this work, it was applied the dual ellipsoidal model of heat input, adapted to the GMAW-CW and compared to the same model over the GMAW, using existing experimental data and predicting the HAZ dimensions in function of weld and welding parameters. The results found had less than 10% error from experimental data in a more refined version of the model, whereas the difficulties to predict cold wire addition influences were not trivial.

Effect of the Heat Input in the Transformation of Retained Austenite in Advanced Steels of Transformation Induced Plasticity (TRIP) Welded with Gas Metal Arc Welding

2013 ◽  
Vol 339 ◽  
pp. 700-705 ◽  
Author(s):  
Victor Lopez ◽  
Arturo Reyes ◽  
Patricia Zambrano
Keyword(s):  
Heat Input ◽  
Arc Welding ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Residual Austenite ◽  
Welding Parameters ◽  
Transformation Induced Plasticity ◽  
Metal Arc Welding

The effect of heat input on the transformation of retained austenite steels transformation induced plasticity (TRIP) was investigated in the heat affected zone (HAZ) of the Gas Metal Arc Welding GMAW process. The determination of retained austenite of the HAZ is important in optimizing the welding parameters when welding TRIP steels, because this will greatly influence the mechanical properties of the welding joint due to the transformation of residual austenite into martensite due to work hardening. Coupons were welded with high and low heat input for investigating the austenite transformation of the base metal due to heat applied by the welding process and was evaluated by optical microscopy and the method of X-Ray Diffraction (XRD). Data analyzed shows that the volume fraction of retained austenite in the HAZ increases with the heat input applied by the welding process, being greater as the heat input increase and decrease the cooling rate, this due to variation in the travel speed of the weld path.

Application of Thermal Analysis Tool for Girth Welding Procedure Qualification

2016 ◽  
Author(s):  
Aditya Dekhane ◽  
Alex Wang ◽  
Yong-Yi Wang ◽  
Marie Quintana
Keyword(s):  
Mechanical Properties ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Welding Parameters ◽  
Analysis Tool ◽  
Thermal Cycles ◽  
Cooling Rates ◽  
Metal Arc Welding ◽  
Girth Welding ◽  
Welding Procedure

The mechanical properties of welds are governed by the final microstructure that develops as an interaction between the chemical composition and cooling rates produced by welding thermal cycles. For welds in modern microalloyed thermomechanically controlled processed (TMCP) pipeline steels, the microstructure and mechanical properties can be extremely sensitive to cooling rates. The development and qualification of welding procedures to achieve targeted mechanical properties is often an iterative process. Accurate knowledge of welding thermal cycles and cooling rates as a function of welding parameters is valuable for optimization of welding process development. This paper covers the development, validation, and application of a girth welding thermal analysis tool. The core of the tool is a numerical model that has a two-dimensional, axi-symmetrical finite element procedure to simulate the transient heat transfer processes both in the weld metal and the heat affected zone (HAZ). The tool takes welding parameters, pipe and bevel geometry, and thermal properties as inputs and predicts thermal cycles and cooling rates in weld metal and HAZ. The comparison of thermal cycles between experimental measurements and the model predictions show the tool was robust and accurate. This tool is particularly effective in understanding the thermal history and resulting microstructure and mechanical properties of welds produced with high-productivity gas metal arc welding (GMAW), such as mechanized dual-torch pulsed gas metal arc welding (DT GMAW-P). The tool was used in optimization of development and qualification of welding procedures of a DT GMAW-P process under a tight time schedule. The actual welds were fabricated according to the optimized welding procedures followed by the mechanical testing of welds. Good agreement was found between the predicted tensile properties and those from experimental tests. The welding procedures were qualified within the tight time schedule by avoiding iterative trials, and reducing the cost associated with the making of trial welds and mechanical testing by approximately 50%. This tool has also been applied in the application of essential welding variables methodology (EWVM) for X80 and X70 linepipe steels [1, 2]. Future applications of the tools include the revamp of the approach to essential variables in welding procedure qualification. In particular, the parameters affecting cooling rates may be “bundled” together towards the one critical factor affecting weld properties, i.e., cooling rate. The individual parameters may be varied beyond the limits in the current codes and standards as long as their combined effects make the cooling rate stay within a narrow band. It is expected that the same framework of approaches to GMAW processes can be extended other welding processes, such as FCAW and SMAW.

scholarly journals Application of Cold Wire Gas Metal Arc Welding for Narrow Gap Welding (NGW) of High Strength Low Alloy Steel

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 335 ◽  
Author(s):  
Rafael Ribeiro ◽  
Paulo Assunção ◽  
Emanuel Dos Santos ◽  
Ademir Filho ◽  
Eduardo Braga ◽  
...  
Keyword(s):  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Parameters ◽  
Narrow Gap ◽  
Dynamic Features ◽  
Narrow Gap Welding ◽  
Cold Wire ◽  
Metal Arc Welding ◽  
Welding Processes

Narrow gap welding is a prevalent technique used to decrease the volume of molten metal and heat required to fill a joint. Consequently, deleterious effects such as distortion and residual stresses may be reduced. One of the fields where narrow groove welding is most employed is pipeline welding where misalignment, productivity and mechanical properties are critical to a successful final assemblage of pipes. This work reports the feasibility of joining pipe sections with 4 mm-wide narrow gaps machined from API X80 linepipe using cold wire gas metal arc welding. Joints were manufactured using the standard gas metal arc welding and the cold wire gas metal arc welding processes, where high speed imaging, and voltage and current monitoring were used to study the arc dynamic features. Standard metallographic procedures were used to study sidewall penetration, and the evolution of the heat affected zone during welding. It was found that cold wire injection stabilizes the arc wandering, decreasing sidewall penetration while almost doubling deposition. However, this also decreases penetration, and incomplete penetration was found in the cold wire specimens as a drawback. However, adjusting the groove geometry or changing the welding parameters would resolve this penetration issue.

An overview on the cold wire pulsed gas metal arc welding

2019 ◽  
Vol 64 (1) ◽  
pp. 123-140 ◽  
Author(s):  
R. A. Ribeiro ◽  
P. D. C. Assunção ◽  
E. B. F. Dos Santos ◽  
E. M. Braga ◽  
A. P. Gerlich
Keyword(s):  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Cold Wire ◽  
Metal Arc Welding

scholarly journals Effects of High Frequency Mechanical Impact on Fatigue Life of Semi-Automated Gas Metal Arc Welding (GTAW) of HSLA Butt Weld

2019 ◽  
Vol 269 ◽  
pp. 06002
Author(s):  
Salina Saidin ◽  
Dahia Andud ◽  
Yupiter H. P. Manurung ◽  
Muhd. Faiz Mat ◽  
Noridzwan Nordin ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Steel Structure ◽  
Welding Parameters ◽  
Butt Weld ◽  
Metal Arc Welding ◽  
Life Enhancement ◽  
Fatigue Life Enhancement

This paper deals with a comprehensive investigation of fatigue life enhancement on semiautomated Gas Metal Arc Welding (GTAW) butt weld joint which is found almost everywhere in Malaysia welding structure steel sectors. The selected material in this study was high strength low alloy steel S460G2+M commonly used extremely in steel structure due to its outstanding mechanical properties. In this investigation, the method for joining the butt weld was conducted by unprofessional welder using semi-automated GMAW. At first, suitable welding parameters were identified and formulated into welding procedure specification (WPS) qualification conforming to AWS D1.1 standard. The test specimens were prepared and tested to ensure the welding quality. Further, the HFMI using Pneumatic Impact Treatment (PIT) technique were applied at the weld toe of the butt weld as tool for fatigue life enhancement. To investigate the influence of HFMI/PIT on the fatigue strength, the specimens were undergone fatigue test using universal fatigue machine using a constant amplitude loading. Finally, the comparison of the fatigue strength of as welded and treated specimens to indicate the beneficial influence of the treatment. Yes, the conduction by unprofessional welder using semi-automatic GMAW, the findings showed the improvement of fatigue strength and slope of S-N curves. In addition, the fracture location of test specimen shows physically affected by shifting from critical weld transition to base metal. The tensile test and hardness value also showed a slight difference as compared to untreated specimens.

scholarly journals Influence of welding method on microstructural creation of welded joints  

2011 ◽  
Vol 57 (Special Issue) ◽  
pp. S50-S56 ◽  
Author(s):  
P. Čičo ◽  
D. Kalincová ◽  
M. Kotus
Keyword(s):  
Welded Joints ◽  
Arc Welding ◽  
Welded Joint ◽  
Gas Metal Arc Welding ◽  
Structural Phase ◽  
Welding Parameters ◽  
Welding Method ◽  
Welding Technology ◽  
Metal Arc Welding

This paper is focused on the analysis of the welding technology influence on the microstructure production and quality of the welded joint. Steel of class STN 41 1375 was selected for the experiment, the samples were welded by arc welding including two methods: a manual one by coated electrode and gas metal arc welding method. Macro and microstructural analyses of the experimental welded joints confirmed that the welding parameters affected the welded joint structure in terms of the grain size and character of the structural phase.

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