scholarly journals Effect of Current on Mechanical Properties and Microstructure of Aluminum 6061 with Gas Tungsten Arc Welding Process

Kapal ◽  
2020 ◽  
Vol 17 (3) ◽  
pp. 107-113
Author(s):  
Tarmizi Tarmizi ◽  
Kevin Daniel Sianturi ◽  
Irfan Irfan

Aluminum 6061 is an aluminum alloy that is widely used in various industrial fields, which heat treatable. However, it can be joined using a welding process. Aluminum joining using the Gas Tungsten Arc Welding (GTAW) process has become the option to produce good quality joints. This research aims to get optimum welding parameters by knowing the mechanical properties and microstructure of the welding results. The GTAW process uses a 25-volt voltage, Argon protective gas flow rate of 15 liters per minute with filler rod ER 5356 with 2.4 mm diameter and electrodes tungsten 2.4 mm in diameter. This process uses a single V butt joint and groove angle of 60° with variations in the current of 100, 110 and 120 A. The results indicate that specimens with a variety of current of 110 A give better results in the absence of defects, have a tensile strength of 152 MPa, and get a hardness value of 87.55 HV, which is the highest compared to the other two specimens. Whereas specimens with the current variation of 100 and 120 A have defects in the weld area. The optimum parameters of the 6061 aluminum GTAW process with a thickness of 6 mm using a current of 110 A bring on better outcomes and mechanical properties than the use of currents of 100 and 120 A.

Teknik ◽  
2021 ◽  
Vol 42 (1) ◽  
pp. 20-28
Author(s):  
Tarmizi Tarmizi ◽  
Yudha Bakti Nugraha ◽  
Irfan Irfan

The welding use correct process parameters will produce joint with optimum in mechanical properties. The current is a very important process parameter in welding. Gas Tungsten Arc Welding process carbon steel A53 Gr B uses current variations can be an option to get the best quality joints. The purpose of this research is to get optimum mechanical properties and microstructure by varying the current. The experimental method uses GTAW process by varying current in welding A 53 Gr B using a single V butt joint and a 5G welding position, the Argon protective gas flow rate of 15 liters per minute with filler rod ER 70 S-6. This process also uses 11-13 Volt voltage with DCEN polarity and current 70, 90, and 110A. Based on ASME Section IX, the test results show that the specimen with a current of 90A gives optimum results with a tensile strength of 480 MPa and a hardness value of 190 HV, whereas specimens with welding current of 70A bring incomplete penetration defects in the weld area. The use of welding current 90A in this research provides welding results with better mechanical properties and microstructure compared to the use of currents of 70 and 110A


Author(s):  
Rishi Pamnani ◽  
M Vasudevan ◽  
P Vasantharaja ◽  
T Jayakumar

DMR249A steel is indigenously developed high strength low alloy (HSLA) steel. The steel is being used for construction of Indian Aircraft Carrier and other new ships under construction at various ship yards in India. In order to enhance the depth of penetration (DOP) achievable in a single pass for gas tungsten arc welding (GTAW) process, activated fluxes were developed for the steel. The process is called activated flux gas tungsten arc welding (A-GTAW). Design of experiments (DOE) approach was employed using response surface methodology (RSM) and Taguchi technique to optimize the welding parameters for achieving maximum DOP in a single pass. Design matrix was generated using DOE techniques and bead on plate experiments were carried out to generate data for influence of welding process variables on DOP. The input variables considered were current, torch speed, and arc gap. The DOP was considered as response variable. The equations correlating DOP with the process parameters were developed for both the optimization techniques. The identified optimum process parameters were validated by carrying out bead on plate experiments. The RMS error of the predicted and measured DOP values for the validation experiments of the RSM (D-optimal) and Taguchi optimization technique was found to be 0.575 and 0.860, respectively. Thus, RSM (D-optimal) was observed to predict optimized welding process parameters for achieving maximum DOP with better accuracy during A-GTAW process.


Author(s):  
Jonathan K. Tatman ◽  
Steven L. McCracken ◽  
Trevor G. Hicks

Predicting weld dilution for machine gas tungsten arc welding (GTAW) is a challenge due to the number of variables associated with the welding process. Proper heat input and power ratio controls are critical in many welding applications to control weld dilution, such as for dissimilar metal welds where low weld dilution is necessary to prevent solidification cracking or for cladding where weld dilution is minimized to maintain corrosion resistance of the clad material. This paper discusses the preliminary development and validation of improved weld dilution, heat input, and power ratio equations for the GTAW process. The new equations incorporate power added for the hot wire GTAW process, filler metal material properties, and the heat used to melt the filler metal when added to the GTAW process. The weld dilution equation was validated by comparing calculated dilution values to measured values from bead-on-plate weld trials performed on a variety of filler metals and substrates. Results of the testing and validation along with limitations of the new equations are discussed.


2020 ◽  
Vol 26 (4) ◽  
pp. 426-431
Author(s):  
Wei LI ◽  
Gaochong LV ◽  
Qiang WANG ◽  
Songtao HUANG

To resolve the problem of grain coarsening occurring in the fusion zone and the heat-affected zone during conventional gas tungsten arc welding(C-GTAW) welded titanium alloy, which severely restricts the improvement of weld mechanical properties, welding experiments on Ti-6Al-4V titanium alloy by adopting ultra-high frequency pulse gas tungsten arc welding (UHFP-GTAW) technique were carried out to study arc characteristics and weld bead microstructure. Combined with image processing technique, arc shapes during welding process were observed by high-speed camera. Meanwhile the average arc pressure under various welding parameters were obtained by adopting pressure measuring equipment with high-precision. In addition, the metallographic samples of the weld cross section were prepared for observing weld bead geometry and microstructure of the fusion zone. The experimental results show that, compared with C-GTAW, UHFP-GTAW process provides larger arc energy density and higher proportion of arc core region to the whole arc area. Moreover, UHFP-GTAW process has the obviously effect on grain refinement, which can decrease the grain size of the fusion zone. The results also revealed that a significant increase of arc pressure while increasing pulse frequency of UHFP-GTAW, which could improve the depth-to-width ratio of weld beads.


Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4016
Author(s):  
Qian Wang ◽  
Junqi Shen ◽  
Shengsun Hu ◽  
Guancheng Zhao ◽  
Jie Zhou

High-quality joining of dissimilar alloys between Fe-36Ni alloy and 304L stainless steel is essential in the manufacturing of LNG tanker. In this study, lap joints of Fe-36Ni and 304L dissimilar alloys were fabricated by a pulsed gas tungsten arc welding (P-GTAW) process. The effects of low-frequency pulse on the appearance, microstructure and mechanical properties of the Fe-36Ni/304L lap joints was investigated. With the increase of frequency, the feature sizes of α (the transition angle of the upper surface of Fe-36Ni to the surface of the weld bead) and R (shortest distance between weld root and weld surface) exhibited downtrend and uptrend, respectively, while La (the maximum weld width of lower sheet) and P (the maximum weld penetration of lower sheet) changed in a smaller range. Fusion zone (FZ) is mainly composed of γ phase and M23C6 during solidification, and M23C6 particles are distributed on the grain boundaries of the cells, which reduced the mechanical properties of joint. The average hardness between 110 HV1 and 136 HV1 is lower than that of the base metals. Fractures of all joints located at the Fe-36Ni side near the weld, and a dimple fracture in all samples indicated a ductile fracture. This study found that the heat input values remain 198.86 J mm−1 and increased pulse frequency can improve the maximum tensile force. The average maximum tensile force of the lap weld is 11.95 kN when pulsed frequency is 15 Hz.


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