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1

Analysis of weld bead characteristics on GMAW by changing wire electrode geometry

Sripriyan K., Ramu M.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 78, nr 2

49--58

EN

Purpose: Welding is one of the important processes for the manufacture of a wide variety of products. Most of the manufactured products have to be produced by welding due to its greater productivity and economical viability. Still quality has to be enhanced in the products. To attain the perfect quality in weld a new attempt has been tried out while existing process are being optimized. In this direction, the conventional Gas Metal Arc Welding (GMAW) has been developed to encourage high welding performance variant. Influence of changing filler metal geometry is one of the ways to improve the capability of giving high deposition rate and penetration. Accordingly, a flat wire arc welding system has been developed and weld bead characteristic has been investigated. The overall results show that, the proposed technique of changing wire electrode geometry can be used effectively to improve the weld bead characteristics. In this article, how does a change in electrode geometry contribute to the weld quality in manufacturing industries, is well- verified by experimental results, which are also explored here.

2

The influence of welding heat input on the microstructure of joints of S1100QL steel in one-pass welding

Nowacki J., Sajek A., Matkowski P.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 4

777--783

EN

Microstructure transformations of a welded joint of the of quenched and tempered advanced high-strength S1100QL steel in relation to the heat input and its effect on the strength of the joint. The gas metal arc welding method was used with varying values of the heat input in the range from 5.5 to 7.1 kJ/cm. Metallographic examination, hardness, impact strength, and tensile strength tests were carried out. Innovative methodology of welding impact test using drop tower impact resistance tester, has been applied. Joints with strength higher than that of welded steel were created. The amount of heat input necessary to produce joints of S1100QL steel whose strength would be higher than that of parent material was determined. The advantages of using S1100QL steel were indicated and a method of one-pass welding that allows for production of joints of optimum strength parameters with the use of mismatched filler metals was presented. As the result of detailed weld cracking dynamics analysis of the S1100QL steel the course of joint deformation was determined as a function of time, loading force and impact energy. It was found that the dynamically loaded samples welded with lower heat input display higher limit of elasticity, which is manifested by higher loading forces and longer deformation time.

3

The role of shielding gas on mechanical, metallurgical and corrosion properties of corten steel welded joints of Railway Coaches using GMAW

John B., Paulraj S., Mathew J.

Advances in Science and Technology. Research Journal

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2016

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Vol. 10, nr 32

156--168

EN

This analysis lays emphasis on finding a suitable combination of shielding gas for welding underframe members such as sole bar of Railway Coaches made of corten steel; for improved mechanical, metallurgical and corrosion properties of welds using copper coated solid MIG/MAG welding filler wire size 1.2 mm conforming to AWS/SFA 5.18 ER 70 S in Semi-automatic GMAW process. Solid filler wire is preferred by welders due to less fumes, practically no slag and easy manipulation of welding torch with smooth wire flow during corrosion repair attention, when compared to Flux cored wire. Three joints using Gas metal arc welding (GMAW) with shielding gases viz., Pure CO2, (80% Ar – 20% CO2 ) and (90% Ar – 10% CO2 ) were made from test pieces cut from Sole bar material of Railway Coach. Study of Mechanical properties such as tensile strength, hardness and toughness revealed that welded joint made using shielding gas (80% Ar – 20% CO2 ) has better Mechanical properties compared to the other two shielding gases and comparable to that of Parent metal. Type of Shielding gas used has influence on the chemical composition and macro & micro structures. The Tafel extrapolation study of freshly ground samples in 3.5% NaCl solution revealed that the welded joint made using shielding gas (80% Ar – 20% CO2 ) has also better corrosion resistance which is comparable to the Parent metal as well as similar commercial steels.

4

Wpływ sposobu napawania rur kotłowych na mikrostrukturę i skład chemiczny napoin

Rozmus-Górnikowska M., Blicharski M., Kusiński J., Kusiński L., Marszycki M.

Inżynieria Materiałowa

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2014

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Vol. 35, nr 1

31--34

PL

Celem pracy była ocena wpływu metody napawania Inconelem 625 rur kotłowych ze stali P235GH i 16Mo3 na mikrostrukturę i skład chemiczny podłoża i napoiny. Badania prowadzono na odcinkach rur kotłowych napawanych stopem niklu Inconel 625 przez czterech różnych producentów stosujących różne metody napawania: CMT, GMAW i GTAW. Wykazano, że bez względu na metodę napawania otrzymane napoiny składają się z następujących stref mikrostruktury: strefy przetopionej, strefy częściowego wymieszania oraz strefy wpływy ciepła (rys. 3). W strefie przetopionej i częściowego wymieszania obserwuje się zwiększoną zawartość Fe (rys. 4). Największą zawartością Fe przy powierzchni powłoki charakteryzują się napoiny, które mają najmniej równomierną powierzchnię wtopienia oraz najmniej gładką powierzchnię zewnętrzną. Przy najmniejszym kącie pochylenia ściegu zawartość Fe zmniejsza się najszybciej w miarę oddalania się od powierzchni wtopienia w kierunku powierzchni napoiny (rys. 6).

EN

The aim of this work was to identify the impact of the cladding method of boiler pipes from P235GH and 16Mo3 steels on the microstructure and chemical composition of substrates and coatings. The investigations were carried out on boiler pipes cladded with Inconel 625. The pipes were cladded in various conditions (CMT, GMAW and GTAW) and were delivered by different suppliers. It has been shown that regardless of the cladding method, the overlays consist of the following microstructural zones: fusion zone, partially mixed zone and heat affected zone (Fig. 3). An increased concentration of Fe was observed in the fusion zone as well as in the partially mixed zone (Fig. 4). The overlays with the least uniform fusion zone and the highest surface roughness were characterized by the highest concentration of Fe. The concentration of Fe in the overlay with the smallest bead slope decreased the quickest (Fig. 6).

5

Detection of short circuit in pulse gas metal arc welding process

Yarlagadda P. K. D. V., Praveen P., Madasu V. K., Rhee S.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 1

328-332

EN

Purpose: The paper discusses several methods of detecting occurrence of short circuit and short circuit severity in pulse gas metal arc welding process (GMAW-P). Design/methodology/approach: Welding experiments with different values of pulsing parameter and simultaneous recording of high speed camera pictures and welding signals (such as current and voltage) were used to identify the occurrence of short circuit and its severity in GMAW-P process. The investigation is based on the measurement of welding signals specifically current and voltage signals and their synchronization with high speed camera to investigate the short circuit phenomenon in GMAW-P process. Findings: The results reveal that short circuit can be detected using signal processing techniques and its severity can be predicted by using statistical models and artificial intelligence techniques in GMAW-P process. Research limitations/implications: Several factors are responsible for short circuit occurrence in GMAW-P process. The results show that voltage and current signal carry rich information about the metal transfer and especially short circuit occurrence in GMAW-P process. Hence it's possible to detect short circuit occurrence in GMAW-P process. Future work should concentrate on development of advance techniques to improve reliability of techniques mentioned in this paper for short circuit detection and prediction in GMAW-P process. Originality/value: For achieving atomization of the welding processes, implementation of real time monitoring of weld quality is essential. Specifically for GMAW-P process which is widely used for light weight metal which is widely gaining popularity in manufacturing industry. However, in case of GMAW-P process hardly any attempt is made to analyse techniques to detect and predict occurrence of short circuit. This paper analyses different techniques that can be employed for real time monitoring and prediction of short circuit and its severity in the GMAW-P process.

6

Mechanizm przechodzenia metalu w przestrzeni łukowej podczas spawania łukowego elektrodą topliwą w osłonach gazowych

Górecki J., Kolasa A.

Prace Naukowe Politechniki Warszawskiej. Mechanika

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2006

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z. 215

111-121

PL

Jednym a podstawowych zjawisk występujących w wiekszości metod spawania łukowego jest przechodzenie metalu w łuku ze stapiającej sie elektrody do jeziorka płynnego metalu. Niniejsze opracowanie opisuje sposoby przechodzenia metalu w łuku, podczas spawania elektrodą topliwą w osłonach gazowych. Przedstawiono najczęściej cytowane w literaturze naukowej i technicznej teorie opisujące mechanizm przechodzenia metalu w łuku spawalniczym. Przedstawiono także wybrane procesy spawania pozwalające na sterowanie procesem przejścia metalu w łuku spawalniczym.

EN

Since the introduction to industry the gas metal are welding process in the late 1940s, it has became one of the most important welding processes which often constitutes a major fraction of the product cost of large structures. It is now used in joining most commercial alloys. There are various modes of metal transfer in gas metal arc welding such as globular, repelled globular, projected spray, streaming, and rotating transfer. These transfer modes show different arc stabilities, weld pool penetrations, spatter production, porosity formation and level of gas entrapment. Mode of metal transfer depends on many operational varaibles such as welding current, voltage, electrode, extension, electrode diameter and polarity or kind of shielding gas. With many factors influencing metal transfer, theoretical models such as the static force balance theory and the pinch instability theory have been proposed to explain the metal transfer phenomenon. Some processes of controlled metal transfer mode are also described.