Titanium is one of the most important microalloy elements of high strength low-alloy steels used in gas transmission industry. In this paper, titanium nano -oxide and titanium nano- carbide were added to two separate samples in the binding point. Then the Shielded metal arc welding (SMAW) was performed on high-strength low alloy (HSLA) steel with high grade of X-65 according to the special welding method of the National Iranian Gas Company. The results show that the percentage of titanium in both nano-alloy samples has been increased compared to the microalloy. The percentage of titanium in the sample of titanium carbide nanoparticles has increased more than that of titanium oxide nanoparticles. The charpy test results show that in the sample containing titanium oxide nanoparticles compared to the sample containing titanium carbide nanoparticles, has been increased by 70%. Also, the final strength (sample containing titanium carbide nanoparticles compared to the sample containing titanium oxide nanoparticles) has been increased by 40%.

In this article the effects of carburizing heat treatment on girth weld with containing titanium oxide and titanium carbide nanoparticles (X-65 grade of gas pipeline) is evaluated. The charpy results show that in the carburized sample containing titanium oxide and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium carbide and titanium carbide nanoparticles), has been respectively increased by 6% and 42%. Also, the ultimate strength carburized sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium oxide and titanium carbide nanoparticles) has been respectively increased by 20% and 28%. The results show that the fatigue life in both carburized nano-alloy samples has been increased. The fatigue life in the carburized sample of titanium carbide nanoparticles has increased more than that of titanium oxide nanoparticles. The fatigue test results show that in the carburized sample containing titanium carbide nanoparticles compared to the tempered sample containing titanium oxide nanoparticles, fatigue life (150-N force) has been increased by 20%. In this loading the fatigue life (tempered sample containing titanium carbide nanoparticles compared to the no heat treatment sample) has been increased by 31%. The results show that the residual stress in both carburized nano-alloy samples has been decreased The hole drilling strain gage results show that in the tempered sample containing titanium oxide oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium oxide nanoparticles and titanium carbide nanoparticles), hoop residual stresses has been respectively decreased by 9% and 6%.

The effects of tempering heat treatment on girth weld containing titanium oxide and titanium carbide nanoparticles (X-65 grade of the gas pipeline) were evaluated. The Charpy results show that it has been respectively increased by 26% and 15% in the tempered sample containing titanium oxide and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium carbide and titanium carbide nanoparticles). Also, the ultimate strength tempered sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (containing titanium oxide and titanium carbide nanoparticles) has been respectively decreased by 6% and 4%. The results show that the fatigue life in both tempered nano-alloy samples has been increased. The fatigue life in the tempered sample of titanium carbide nanoparticles has increased more than the fatigue life in titanium oxide nanoparticles. The fatigue test results show that in the tempered sample containing titanium carbide nanoparticles compared to the tempered sample containing titanium oxide nanoparticles, fatigue life (150-N force) has been increased by 30%. In this loading, the fatigue life (tempered sample containing titanium carbide nanoparticles compared to the no heat treatment sample) has been increased by 19%. The hole drilling strain gage results show that in the tempered sample containing titanium oxide nanoparticles and titanium carbide nanoparticles, hoop residual stresses have been respectively decreased by 48% and 45% compared to the no heat treatment sample (containing titanium oxide and titanium carbide nanoparticles).

Titanium is one of the most important microalloy elements used in the gas transmission industry. In this paper, titanium nano-oxide and titanium nano-carbide were added to two separate samples. Then the shielded metal arc welding (SMAW) was performed on high-strength low alloy steel according to welding procedure specification of the national Iranian gas company. The effects of annealing heat treatment on girth weld with containing titanium oxide and titanium carbide nanoparticles (X-65 grade of gas transmission pipeline) were evaluated. The Charpy test results show that in the annealed sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the no heat treatment sample (Containing titanium carbide nanoparticles and titanium carbide nanoparticles), energy absorbed has been respectively increased by %13 and %9. Also, the ultimate strength of the annealed sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the non-heat treated sample has been respectively decreased by %8 and %3. The fatigue life in both annealed nano-alloy samples has been increased. Also, the fatigue life in the annealed sample of titanium carbide nanoparticles has increased more than fatigue life in the titanium oxide nanoparticles. The fatigue life (Annealed sample containing titanium carbide nanoparticles compared to the no heat treatment sample) has been increased by %16. The hole drilling strain gage results show that in the annealed sample containing titanium oxide nanoparticles and titanium carbide nanoparticles compared to the non-heat treated sample, hoop residual stresses has been respectively decreased by %31 and %19.

This paper reports an investigation carried out to determine the effect of aluminum oxide Nano-particles coated with manganese on the microstructure and mechanical properties of single-pass butt joint of low carbon steel plates of 6.0 mm thicknesses using gas metal arc welding process. After selecting appropriate welding parameters and adding 0.25 gr and 0.5 gr of Nano-particles into the joint line and carrying out the welding, the samples were prepared for micro hardness and tensile tests. Furthermore, the sample with optimum Nano-particles having the highest ultimate tensile strength and without having any visible and metallurgical defects in the microstructure was selected for further investigation.  Subsequently, microstructures of the weld without and with optimum Nano-particles were studied using optical microscopy and scanning electron microscopy (SEM) and the fractured surface of the weld obtained from tensile testing was investigated for the samples without Nano particles and the optimum sample with Nano materials were studied. The results show that Nano-particles added to the weld pool penetrated into the weld zone and helped in formation of acicular ferrite in the microstructure. Based on the results obtained, ultimate tensile strength and percentage of elongation of samples without Nano-particles and with optimum Nano-particles were increased from 387 MPa and 6.8% to 408 MPa and 13.6%, respectively. In addition, the average hardness of the weld metal without Nano-particles and with optimum Nano-particles were increased from 158 VHN to 172 VHN respectively

One of the quality characteristics of welded joints in gas metal arc welding (GMAW) is weld height (WH). This paper highlights an experimental study carried out to develop a model using artificial neural network (ANN), to predict WH in GMAW in the presence of TiO2 nano-particles. For developing the model, the arc voltage, welding current, welding speed, percentage of Ar in Ar-CO2 mixture and thickness of TiO2 nano-particles were considered as input parameters and WBH as the response. A Doehlert design matrix was employed in the experiments to generate experimental data. The ANN model was developed and validated by conducting five extra runs. The remarkable outcome of this study is the mechanism of arc constriction due to interacting effects between welding input parameters and TiO2 nano-particles. Moreover, the results showed that increasing thickness of TiO2 nano-particles up to almost 0.9 mm increased weld height whereas, its further increase up to 1.0 mm, decreased weld height subsequently. In fact, this variation in weld height could be due to thermal dissociation of TiO2 nano-particles and CO2 releasing oxygen onto weld pool surface, which influenced its surface tension and consequently, changed direction of the Marangoni convection of fluid flow in weld pool and as a result, affected WH. For ANN technique, MSEtrain=0.0066, MSEvalidation=0.0063 and MSEtest=0.0093. Finally, it is to be concluded that ANN is an accurate technique for predicting weld height.

In this paper a new attempt is made by optimization of welding parameters in welded butt joint the Hybrid LM25 Aluminium Metal Matrix Nano Composite Cylindrical Rod Samples. Here Hybrid LM25 Aluminium metal matrix nano composite (AMMNC) is made by using stir casting method. Here Base metal LM25 Aluminium alloy is adding the reinforcing matrix as 2% of nano Silicon carbide particles along with 3% of nano alumina for producing Hybrid AMMNC Samples. Joining of this Hybrid AMMNC samples are done by using TIG welding, due to its low cost and good quality of welds among arc welding processes these reinforcements are dispersed as nano particles to get a benefit of enhancing in their strength. While joining of hybrid AMMNC cylindrical rod butt joint by using TIG welding process. To optimize the TIG welding parameters such as Welding pulse current, Arc voltage and Shielding gas flow rate experiment is designed using One-Factor Multilevel-Categorical Factor technique. By conducting the experiment, effect of welding parameters such as welding pulse current, Arc Voltage and shielding gas flow rate on weld centre micro hardness is evaluated. Regression equation is developed using Design-Expert version 11 statistical software to predict the weld centre micro hardness. Correlation co-efficient (r2) showed 0.95 and error % showed less than 5% which means the regression equations are developed in the most consistent. Empirical model is developed to optimize the pulsed current parameters of welding is also performed using Design Expert - statistical software. Optimized values for pulse on welding time, arc voltage and shielding gas flow rates are 120A, 21V and 12 l/m respectively. Optimized predicted value of weld centre micro hardness has been observed as 100HV. Trial runs are performed for optimized PCTIG welding condition to check the consistency of the model, which resulted only 5% of deviation between experimental values and predicted values. It shows the optimized welding pulsed current, Arc Voltage and Shielding gas flow rate parameters resulted in higher micro hardness value which implies that strength of the weld is increased with respect to optimize welding parameters. In addition to investigate the temperature distribution in optimized Hardness value of welded AMMNC sample. Then heat fusion in the size and distribution of heat source, the travel speed, the heat conduction in the welding direction and the surface heat loss during welding are considered. A numerical scheme is developed to solve the three dimensional problem. With the help of a mathematical model, the effect of welding parameters such as heat input of the weld, preheating of the work piece and moving velocity of heat source on weld penetration in welded AMMNC cylindrical rod samples are discussed. The steady-state temperature profiles of the welded AMMNC samples are solved by finite difference method. In addition, a thermal experiment such as Heat Flux Differential Scanning Calorimeter Experiment is conducted to verify the theoretical results and Numerical results in ANSYS software. The predicted values from the proposed model are compared with the experimental data of optimized welded AMMNC samples.

This paper reports the applicability of fuzzy logig (FL) to predict the hardness of melt zone (HMZ) during the gas metal arc welding (GMAW) process, which is affected by the combined effect of ZrO2 nano-particles and welding input parameters. The arc voltage, welding current, welding speed, stick-out, and ZrO2 nano-particles were used as the input parameters and HMZ as the response to develop FL model. The predicted results from FL were compared with the experimental data. The most important input parameter affecting the HMZs was the addition of ZrO2 nanoparticle coatings with a thickness of 1 mm, which increased the hardness from 78 to 84 HRB. The correlation factor value obtained was 99.98% between the measured and predicted values of HMZ. The results showed that FL is an accurate and reliable technique for predicting HMZ because of its low error rate. Also, the presence of ZrO2 nano-particles in the weld pool has increased the penetration up to 2 times.

The main aim of this experiment is to investigate the effects of Nano-size Al2O3 on the mechanical properties and microstructure of multi-passes friction stir welding of Al 2024 lap joint. Nano particles were added into the joint line. A combination of rotational speed and travelling speeds were performed. Optical microscopy and scanning electron microscope were used to investigate the microstructure and fracture surface of samples respectively. Optimum condition (sample) was selected due to highest ultimate tensile strength (UTS). It was seen that sample which included Nano particles and fabricated by 1400 rev/min rotational speed and 16 mm/min travelling speed in second pass of continues welding had improvement in UTS in comparison to one pass welded sample of particle free and after that increasing the number of passes reduce the UTS. The average micro hardness of the sample which was particle rich were increased in comparison to particle free sample in nugget zone. Increasing the number of passes was not effect average micro hardness in nugget zone significantly. Grain sizes were reduced by 2 passes welding and after that no significant reduction has been seen.

The purpose of this study was to examine the effect of adding Nano particles such as Nano Carbon Tube during Friction Stir Welding (FSW) on dissimilar Al alloy joints. More specifically, both FSW and Friction Stir Processing (FSP) were performed simultaneously to investigate the effect of adding Nano particles on mechanical properties and microstructure of the weld zone for joining AA5754-H22 and AA6063-T4aluminum alloys. Reliability of the joints was tested by non-destructive tests such as visual inspection, ultrasonic, and radiography. The global mechanical behaviors of dissimilar welds were similar to that of the base material. Important losses in ductility were also reported for dissimilar welds. Microstructural evaluation of fractured surfaces indicated that ductile fracture was the major mechanism of similar and dissimilar welds. We expected that the locks for dislocation moving would improve the mechanical properties of the weld zone. Also, the friction coefficient in the two-passes welded sample was about 30% lower than the friction coefficient of the base metal. On the bases of the wear resistance of hardness and the coefficient of friction, it was concluded that the wear resistance of the surface Nano-composite produced had also increased in the stir zone.