This paper deals with the investigation of the microstructure and hardness of steel samples cladded with satellite 6-WC composites by using gas tungsten arc welding ((GTAW)) process. For this purpose, steel samples were coated with unreinforced and reinforced stellite (by 20, 30 and 40 wt.% WC). The cladded samples were evaluated by metallographic studies, microhardness measurement and X-ray diffraction analysis. In order to reduce dilution and to increase the hardness, samples were coated by two layers of similar chemical composition. The results indicated that in samples cladded by reinforced stellite, with an increase in tungsten carbide content, the amount of hypoeutectic phase (g+ (g+WC)) increased. This is accompanied by an increase in hardness.

Purpose: Extent of an application and importance of a welding industry and economic opportunities of this industry need to develop appropriate strategies to pave the way for the economic growth as a strategic industry with sustainable competitive advantage. The high cost of the gas tungsten arc welding ((GTAW)) process in a welding industry due to the advantages of excellent welding quality and low complexity of this process requires management. Therefore, careful study and evaluation in the correct use of the (GTAW) process with financial resources seems to be very necessary. Modeling leads to efficient decision making along with competitive advantage in strategic planning. Today, by planning, sustainability goals and considerations can also be achieved in addition to achieving economic goals. Methodology: In this study, a linear programming model for the problem of minimizing the cost of the (GTAW) process according to different automatic or manual conditions is presented by a skilled welding operator. GAMS software is used to solve the problem and validate the proposed model. Finally, to evaluate the applicability of the model, four scenarios of the case study are solved and explained as well as sensitivity analysis. Findings: The results show that from an economic point of view, the proposed model can reduce costs and increase efficiency and customer satisfaction. The proposed approach leads to the improvement of the shielded tungsten arc welding process and the increase of management insight. Originality/Value: Mathematical cost modeling can provide a comprehensive analysis of management decisions. The cost minimization model helps managers to understand the cost structure and behavior. Considering the scope of welding application, minimizing the costs of this activity will lead to a reduction in the total cost of an industry.

This paper investigates the weldability of super-duplex steel hollow pipes, which are welded by gas tungsten arc welding ((GTAW)) process, using destructive and non-destructive tests. Non-destructive inspections were performed by visual inspection and radiography, which indicate the proper quality of the performed welds. Material analysis, metallographic, tensile and hardness tests have been performed for different welding positions. The effects of the welding position on the microstructure and mechanical properties of the welded specimens were investigated. The results of the metallographic test reveal the good balance between austenite-ferrite phases in the weld zone. According to materials analysis, chromium to nickel weight percent is higher at the 12 o’clock position. The hardness test results show that the average hardness is the same in different welding positions. The presented results indicate the good weldability of the super-duplex steel pipes fabricated by the (GTAW) process. The weldability assessment of the (GTAW) super-duplex steel hollow pipes using both destructive and non-destructive tests, at different welding positions, is an innovative research.

This work systematically explores the e ects of process parameters on the technological responses, including Tensile Force (TF) and the Average Micro-Hardness (AMH), in gas tungsten arc welding ((GTAW)) of titanium. process parameters are welding current (I), gas ow rate (F), and arc gap (G). The objective of this work is to improve tensile strength with respect to micro-hardness constraints. (GTAW) welding machine was utilized with the Box-Behnken matrix to conduct experimental trails. The nonlinear relationships between welding parameters and responses were developed using Response Surface Method (RSM). Subsequently, an optimization technique, entitled Desirability Approach (DA), was used to analyze the trade-o among the considered responses and to  nd the optimal parameters. Conformity test was carried out in order to evaluate the accuracy of optimal values. The results showed that welding current had the greatest in uence on the outputs among all factors. The measured improvements with optimal parameters of TF and AMH were approximately 4. 10% and 6. 12%, respectively, in comparison with the initial setting. The hybrid approach comprising RSM and DA was found an e ective method for obtaining signi cantly optimal values in (GTAW) processes.

In this study, Astsloy85Mo powder metallurgy steel specimens were surface melted using tungsten Inert gas (TIG) process. The effects of different parameters of the process on the microstructure, hardness, and wear resistance of the melted surfaces were studied using optical and scanning electron microscope equipped with EDS, Vickers hardness unit and pin on flat wear test machine. Surface melting resulted in structural refinement and the hardness of the melted layers reached to the values of up to 800 HV10, more than five times of that of the base PM steel which was about 150 HV10. Moreover, surface melting reduced the wear rate to 100 times lower than that of the base steel. It can be concluded that TIG can be used effectively for surface melting to improve the wear resistance of the Astaloy 85Mo powder metallurgy steel surface.

In this paper, the distribution of temperature and thermal cycle in gas tungsten arc welding of stainless steel 304 is studied. The welding operation was performed under different heat inputs of 540 and 782 kJ/mm on the plates with 2 mm thickness. The Abaqus software was employed for simulation. The volumetric heat distribution, according to the double ellipsoidal (Goldak) model, was considered as the heat source of the welding and DFLUX subroutine was coded by FORTRAN. The simulation results were compared with the Rosenthal and Adams models and experimental results. The simulation results with both heat inputs are well compatible with the cross section dimensions of the welds, while the Rosenthal model predicts a smaller welds’ pool size. The temperature-time curves obtained from the simulation and Rosenthal model have considerable differences but their predicted cooling time and rate in the temperature range of 800 to 500 ° c, especially in heat input of 782 kJ/mm, are close to each other (the difference is less than 7. 2%). The results also showed that the maximum temperature of the regions farther from the fusion boundary in Adams model is predicted higher than that of simulation and Rosenthal model, while the results of simulation and Rosenthal model are closer to each other.

Automobile designers are always looking for new technologies to reduce vehicle weight and manufacturing costs. An opportunity to meet these seemingly conflicting requirements is through the use of Tailor-Welded Blanks (TWBs). welding method and its parameters have an important effect on the formability and mechanical properties of TWBs. In this study, gas tungsten arc welding ((GTAW)) is used to join aluminum TWBs. Aluminum TWBs consist of 6061 aluminum sheets with different thicknesses of 1mm and 2mm. Main parameters of (GTAW) consist of welding current, shielding gas pressure, welding speed and diameter of filler material are investigated in the present study. Design of experiment based on the Tauguchi method is used to investigate the effect of each parameter and also parameters interaction. Erichsen formability test (out-of-plane forming test) is used for formability investigation of aluminum TWBs. Forming height of Erichsen test is used as a criterion to study the effect of (GTAW) parameters on the quality of aluminum TWBs. The obtained results indicate that shielding gas pressure and welding speed have the greatest impact on the formability of aluminum TWBs.

In this research, Ti-6Al-4V alloy sheet with a thickness of one millimeter with butt joint design was welded by tungsten-gas arc welding process using pulse current (PC(GTAW)) and using AMS 4954G filler metal. In this study, the effect of pulse system frequency on microstructure and mechanical properties was investigated by optical microscopy, Vickers hardness and tensile strength tests. In the non-frequency welding sample, due to the lack of pulse current and lower cooling rate of the molten pool, the formation of large amounts of soft phases of the Weidmann-Statten layer in the weld metal region is possible. Finally, in this method, the lowest average hardness of 341 Vickers was obtained. The experimental results showed that using pulsed current and increasing the pulse frequency up to 450 Hz increased the cooling rate of the molten pool, followed by increasing the amount of martensitic phase α 'in the form of a basket in the weld metal region and finally increasing the average microhardness in this region. In other words, using the maximum frequency led to a significant increase in hardness up to 367 Vickers in the weld zone. Finally, using the tensile strength test, it was shown that in all the samples, failure occurred from the base metal area, which was a very good phenomenon due to the proper welding quality of the samples.