scholarly journals Strain effect on microstructural properties of SUS 304L joint by PAW+GTAW

Author(s):  
Wang Juan ◽  
Li Yajiang ◽  
Wang Qi ◽  
Liu Kun ◽  
Li Hang

AbstractJIS SUS 304L stainless steel was joined by a combination welding process of plasma arc welding and gas tungsten arc welding (PAW+GTAW). Then pre-strain treatment on 304L welded joint of 9 % was carried out using uniaxial quasi-static tensile at room temperature. Effect of strain on microstructure evolution in joint was analyzed by field emission scanning electron microscope (FESEM) and on mechanical properties was also studied. The results indicated that the pre-strain rate of 304L joint showed inhomogeneity including 3 % in the weld metal and 13 % in the heat-affected zone (HAZ), which induced martensitic transformation occurring in HAZ. Tensile strength of the joint increased from 700 MPa as welded to 804 MPa after pre-strain treatment at room temperature, and it reached 1700 MPa from 1480 MPa as welded at low temperature of −196 °C. Impact energy in the HAZ was the least among the whole 304L weld, but it was still 94 J at −196 °C after pre-strain. The fracture morphology showed large numbered of cleavage steps with elongated parabolic dimples.

2021 ◽  
Author(s):  
Juan Wang ◽  
Yajiang Li ◽  
Qi Wang ◽  
Kun Liu ◽  
Hang Li

Abstract 304L stainless steel was joined by a combination welding process of plasma arc welding and gas tungsten arc welding (PAW + GTAW). Then pre-strain treatment on 304L welded joint by 9% was carried out using uniaxial static tensile at room temperature. Effect of strain on microstructure evolution in joint was analyzed by field emission scanning electron microscope (FESEM) and on mechanical properties was also studied. The results indicated that the strain rate of 304L joint showed inhomogeneity including 3% in the weld metal and 13% in the heat affected zone (HAZ), which induced martensitic transformation occurring in HAZ. Tensile strength of the joint increased from 700MPa as welded to 804MPa after strain at room temperature and it reached 1700MPa from 1480MPa at low temperature of -196℃. Impact toughness in HAZ was the least among the whole joint, but it was still 94J at -196℃after strain. The fracture surface showed large numbered of cleavage steps with elongated parabolic dimples.


Author(s):  
Hanmant Virbhadra Shete ◽  
Sanket Dattatraya Gite

Gas metal arc welding (GMAW) is the leading process in the development of arc welding process for higher productivity and quality. In this study, the effect of process parameters of argon gas welding on the strength of T type welded joint of AISI 310 stainless steel is analyzed. The Taguchi technique is used to develop the experimental matrix and tensile strength of the welded joint is measured using experimental method and finite element method. Optimization of input parameter is performed for the maximum tensile strength of welded joint using ANOVA. The results showed that welding speed is the most significant factor affecting the tensile strength followed by voltage in argon gas metal arc welding (AGMAW) process. Argon gas welding process performance with regard to the tensile strength is optimized at voltage: 18.5 V, wire feed speed: 63 m/min and welding speed: 0.36 m/min.


Author(s):  
Cole Homer ◽  
Epstein Seymour ◽  
Peace Jon

Fabrication and repair of aluminum components and structures commonly involves the use of electric arc welding. The interaction of the arc and the metal being welded generates ultraviolet radiation, metallic oxides, fumes, and gases. Aluminum is seldom used as the pure metal but is often alloyed with other metals to improve strength and other physical properties. Therefore, the exact composition of any emissions will depend on the welding process and the particular aluminum alloy being welded. To quantify such emissions, The Aluminum Association sponsored several studies to characterize arc welding emissions by the gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) processes for various combinations of base and filler alloys. In all cases, the tests were conducted under conditions that could be found in a production weld shop without forced ventilation. The concentrations of each analyte that a welder could be exposed to were greatly affected by the welding process, the composition of the base and filler alloys, the position of the welder, and the welding helmet. The results obtained can be used by employers to identify and control potential hazards associated with the welding of aluminum alloys and can provide the basis for hazard communication to employees involved in the welding of these alloys.


Author(s):  
Sorush Niknamian

Nowadays, welding of dissimilar metals has become significant. In this process, a number of parameters including but not limited to type of electrode, amount of current, preheating temperature, and welding rate, that are essential to be taken into account. For welding of dissimilar metals, various methods are exploited including shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW). The stimulus for studying welding of 304L stainless steel to pure copper originates from difficulties in joining copper parts of           water-circulating molds to their steel part. In this study, the welding is performed on plates of steel and copper using SMAW, GTAW and combined SMAW+GTAW welding methods with    EL-CuMn2, ENiCrMo-6 and ER70S-4 electrodes. In order to investigate the microstructure and corrosion resistance behavior of welds, the samples were characterized using microstructural study and polarization test. It was observed that among all four welding methods, only combined SMAW+GTAW welding process resulted in successful joint between 304L stainless steel and copper. Both obtained joints possess suitable microstructure and corrosion resistance.


2016 ◽  
Vol 852 ◽  
pp. 349-354 ◽  
Author(s):  
R. Devanathan ◽  
Sanjivi Arul ◽  
T. Venkatamuni ◽  
D. Yuvarajan ◽  
D. Christopher Selvam

The consequence of sub-zero treatment on the mechanical properties of welded AA6082-T6 by Gas Tungsten Arc Welding (GTAW) which in turn softens the heat concentrated welded region owing to dissolution of the strengthening precipitates. The sub-zero i.e. Shallow Cryogenic Treatment (SCT) is carried out on GTAW welded plate having a thickness of 6 mm at -77°C by varying the electrode travel speed and sub-zero treatment periods. Welded region of AA6082 were tested for hardness and microstructure by adapting three different conditions such as welded, post weld artificial aging with and without sub-zero treatment. Result revealed that the amount of softening in the welded region is indirectly proportional to electrode travel speed during welding process. It is also observed that the post weld SCT with artificial aging has increased the micro hardness values on the welded region as a consequence of the reactivation in the sequence of precipitation.


1999 ◽  
Author(s):  
Shaobin Zhang ◽  
YuMing Zhang

Abstract Stability of the keyhole plays a fundamental role in producing quality welds in keyhole plasma arc welding. Currently, keyhole size is assumed to be a measurement of its stability. To verify this idea, keyhole and weld pool were simultaneously imaged from the opposite side of the welding torch. Experimental results revealed that the width of the keyhole was not correlative with the stability of the keyhole: as long as the keyhole mode was maintained, the width remained constant despite the changes in the welding current and speed. However, it can be used to estimate the lower limit of the pool width for preventing keyhole collapse. Also, the upper limit of the pool width for preventing burn-through is approximately fixed for given applications. Hence, in this study, pool width, its upper limit, and keyhole width were used to determine the margins of the process from collapse and burn-through. To measure the state of the stability of the keyhole process, the stability distance and stability factor were proposed. Based on the imaging system used, the state of the stability can be monitored in real-time.


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