Mild Steel Joints Research Articles

Numerical analysis of butt and lap welded titanium reinforced mild steel joints

Abstract Gas Metal Arc Welding involves complex Multiphysics. The application of numerical modelling helps to understand aspects of the complex phenomena that occur in typical welding processes. In this study, a three-dimensional transient thermal analysis was carried out on both butt and lap joint welded titanium reinforced mild steel sheets using ANSYS Mechanical. A modified Gaussian Equation was adopted to simulate the GMAW transient heat source. The temperature distribution across the weld zones of the butt and lap joints were obtained from the numerical analysis. The same analysis was also carried out for unreinforced butt and lap joints. The temperature history of both the reinforced and unreinforced butt and lap joints were compared and correlated with the microstructural evolution observed across the various weld zones. The weld pool geometries of both reinforced and unreinforced butt and lap joints were estimated from the numerical analysis. These geometries were compared with the weld pool dimensions obtained from experimental data. The temperature history obtained for the reinforced and unreinforced butt and lap joints correlated well with the microstructural evolution across the zones. It was also estimated that the peak temperatures of the reinforced butt joints were higher than those of the unreinforced butt joints indicating that the titanium reinforcement could have induced a slower cooling rate. The estimated weld pool geometries of the lap joints obtained from the numerical analysis were in good agreement with experimental data with less than 10% relative error for both reinforced and unreinforced lap joints. The numerically obtained depth of penetration of the butt joint agreed with experimental results with less than 10% relative error. The modified Gaussian equation used to simulate the transient heat source was shown to be capable of predicting temperature histories and weld geometries of reinforced steel sheets to an acceptable degree.

Characterization of tool wear in similar and dissimilar joints of MS and SS using EAFSW

Abstract Friction Stir Welding (FSW) faces many issues while joining high strength material. In this study an external secondary heat source from a DC source kept at 4 V supply has been used to in between the tool and the workpiece to give an external heat source to FSW and use the method as Electrically Assisted Friction Stir Welding (EAFSW) process. This study represents analysis of mechanical properties of Mild steel (MS) and Stainless-Steel (SS) joint, made by both FSW and EAFSW. An effect of the secondary heat source of electric energy on the mechanical property of the joint and to the tool wear while joining similar and dissimilar material of MS and SS has also been studied. The study represented the effect of the addition of a secondary heat source of an electric current heating to FSW and the impact of various process parameters like tool rpm and feed on the tool wear. The results have been shown to express an expected tool life of WC tool material for joining mild steel and stainless steel. Th experimentation has proved the suitability of Tungsten Carbide as tool material for joining high strength material such as MS and SS. It has also been observed that with suitable utilization of process parameters and secondary heat sources, the heat at the nugget zone increases causing better mixing of the nugget zone. Due to a generation of higher heat at the nugget zone, less tangential and radial load occurs at the tool pin resulting less tool wear and better tool life.

Study of mechanical properties of mild steel joint made by electrically assisted friction stir welding using DC and AC

Abstract Hybrid Friction Stir Welding (FSW) has the ability to join high meting point materials, it can also increase the joint efficiency and reduce the tool wear. Generally, in the hybrid FSW, the work pieces to be welded are preheated, post heated or additional heat is provided with some external sources. Different techniques are being studied upon to heat the work pieces. Use of Plasma, Induction, Ultrasonic Vibration, Electric Assistance, etc., are few of the techniques. In the present study, mechanical properties of welded joints using conventional FSW have compared with that of Electrically Assisted Friction Stir Welding (EAFSW) with two different approaches. In the first case, a Direct Current has been used to preheat the carbon steel plates (CS to IS2062 Gr B). In the other case, an alternating current has been used to preheat the plates. The hardness, ultimate tensile strength and weld efficiency of the welded joints were found out for the above-mentioned cases and a comparative study of the mechanical properties have been done. It has been observed that with DC in EAFSW, better joint efficiency has been observed whereas, with AC uniform hardness, in both advancing and retreating side of the joint, has been concluded.

Effect of adding TiO2 nanoparticles on the impact toughness for welding joints of mild steel

ABSTRACT The application of nanotechnology in the welding process has great importance in developing the mechanical properties of welding joints. The aim of this paper was to investigated the effect of addition titanium dioxide nanoparticles(TiO2) to welding joints by using cold spary technique and study the possibility of improving the impact toughness of the welding joint and increase its operation life. Three weight fraction are used of TiO2 (0.75%, 1.5%, and 2%).The results showed there are improvements in the Impact toughness of welded joints with an increase of TiO2 concentrations. The average Impact toughness for the welded sample without TiO2 was (162.4 J), while the average Impact toughness for the welded sample with (1.5) % TiO2 NPs. was (231.2 J) at increasing ratio of (42.36 %) due to the good toughness properties of TiO2 that increase the toughness of welding zone. The Microstructure image by SEM showed that the addition of TiO2 decreases the grain size in the welding zone and makes it more homogeneous, which gives it more toughness. The EDS analysis shows that increase TiO2 NPs leads to increase the amount of Ti and decrease the amount of Mn, and Si.

Microstructure and Mechanical Properties of Low-Carbon Q235 Steel Welded Using Friction Stir Welding

This study focuses on the microstructure and mechanical properties of the joints of Q235 mild steel, which was formed by the friction stir welding (FSW). The results indicated that, after the FSW, the heat-affected zone (HAZ) of the retreating side (HAZRS) and the HAZ of the advancing side (HAZAS) recovered under the influence of the heating cycle. The transformation of the phases in the thermo-mechanically affected zone (TMAZ) of the retreating side (TMAZRS), the stir zone (SZ) and the TMAZ of the advancing side (TMAZAS) generated the pearlite and acicular ferrite. The continuous dynamic recrystallization occurred in all the three zones, whereas the grains were refined. The SZ mainly consisted of D1, D2 and F shear textures, while the TMAZAS was made up of only the F shear texture. The fine-grained structure, pearlite and the acicular ferrite improved the hardness and tensile strength of the joint. Its ultimate tensile strength was 479 MPa, which was 1.3% higher than that of the base metal. However, the uniform elongation was 16%, which showed a decrease of 33%. The fracture was a ductile fracture with the appearance of dimples. Besides, the joints of the FSW showed an excellent bending performance.

Optimization of Gas Metal Arc Welding (GMAW) Parameters for Minimum Distortion of T Welded Joints of A36 Mild Steel by Taguchi Method

In this study, the GMAW parameters for welding of A36 mild steel have been investigated to get the minimum of distortion. The type of welded joint used was square groove T-joint fillet weld with filler wire ER70S-6. The welding current and the welding speed were selected as input parameters while the response used was distortion (longitudinal bending distortion and angular distortion). Taguchi method was used to determine optimal welding parameters which the minimum distortion. Design of experiment was set two factors with three level in each factor and three replication, so the L9 Taguchi’s orthogonal array was applied. The minimum conditions were determined using S/N ratio with a quality character of smaller is better (SB). In addition, to determine the significance of the welding parameters used ANOVA. The results show that the welding current of 170 A and the welding speed of 4.0 mm/s were obtained as the minimum of longitudinal bending distortion and angular distortion. Based on analysis of variance, the welding current was a parameter that greatly affects the longitudinal bending distortion with the percentage contribution of 64.36% while angular distortion was strongly influenced by welding speed parameter with the percentage contribution of 53.38%.

Experimental Study Improving The Friction in The Surface of Cold Form Steel Connections Using Adhesive

The purpose of this study is to test the strength of light steel joints using screws and the addition of adhesives to the surface of the joint. The addition of adhesive is done to increase the frictional force on the surface of the joint. The study was carried out experimentally by giving axial tensile strength to the specimens. The specimen is a mild steel connection made from a lip channel profile that is connected back to back with 2 screws and has 2 variables, namely adhesive and without adhesive. Each variable has 3 samples. The experimental results show that the addition of adhesives to the joint system is proven to increase friction. This shows that the joints that use adhesives have a greater strength of 17.20% than the joints without adhesives. The mechanism of collapse of the joint using adhesive starts from the collapse in the friction plane, then the screw undergoes tilting and subsequently experiences a collapse in the fused plane. From the results of this study it was concluded that the use of adhesives can be used as an alternative to increase the frictional force on the surface of the mild steel joints.

Neutron diffraction bulk texture study with impact property correlation of electron beam welded dissimilar Fe-7%Al alloy to steel joints

Present work focused on the crystallographic bulk texture study of dissimilar Fe-7percentage Al alloy to mild steel joints by electron beam welding using time-of-flight neutron diffraction technique. Textural properties directly correlated with V-notch Charpy impact study. Different processing conditions like the use of beam oscillation and by changing welding speed on texture change and its impact on the performance of the joint was evaluated. Neutron diffraction was performed using general material diffractometer beamline at ISIS neutron radiation source. Texture analysis and their variation obtained in terms of pole-figures, inverse pole figures and orientation distribution functions (ODFs). Beam oscillation shows a uniform and ordered textured grains in both fusion zone (FZ) and heat-affected zone (HAZ) due to more heat mixing that reduced unidirectional solidification gradient. ODF study reveals more gamma fibre components in both FZ and HAZ compared to its non-oscillating counterparts and higher welding speed joints, which predominantly shows more Goss, rotated Goss and cube/alpha fibre components. Charpy impact strength shows approximately 60% improvement in value for the joints, which was prepared by using beam oscillation whereas 20% reduction for higher welding speed condition. Also, X-ray tomography study of Charpy broke sample showed very lesser and shallow cracks and in smaller volume percentage of 0.45 compared to joints produced by the non-oscillating beam showing maximum value of 2.99%.

Effect of graphene oxide and reduced graphene oxide nanosheets on the microstructure and mechanical properties of mild steel jointing by flux-cored arc welding

The effect of graphene oxide (GO) and reduced graphene oxide (RGO) nanosheets on the microstructure and mechanical properties of welded joints of mild steel was evaluated by flux-cored arc welding. GO was synthesized by the Hummer's method and was reduced under hydrothermal conditions at a pressure of 1.1 MPa at 180°C for 12 h. 1, 3, and 10 mg/mL paste fillers were used in GO and RGO, and applied to the weld notch. The results clearly showed that by increasing the concentration of RGO up to 10 mg/mL, the tensile strength and hardness of the weld metal were improved by approximately 20.5% and 38.4%, respectively, because the coarse grains were changed into fine domains. The domain of the nanosheets cluster was 19.85 × 10−9 m. Specifically, the RGO nanosheets contributed to modifying the mechanical properties of the welded steel, likely due to dislocation pinning.

A study of spot weld pull-out failure (PF) mechanism under different loading conditions for stainless steel and mild steel joints

ABSTRACTSpot weld pull-out failures (PFs) on mild steel and stainless steel joints were investigated under different loading conditions using lap-shear test, cross-tension (KSII) test and coach-peel test. Regardless of the joint type, joints tested with lap-shear test showed the highest weld strength followed by KSII and coach-peel tests, respectively, for the same welding current. Analyses with experimental samples and finite element analysis showed that PFs due to different loading conditions were governed by either tensile stress, shear stress or bending stress. The tendency to fail via weld PF increased from welds tested with KSII test, coach-peel test and lap-shear test for similar steel joints within a range of welding currents. This study also showed that the weld diameters for PF depend on the joint type as well as loading conditions and did not conform to the recommended weld diameters by the automotive standards.

A Review on Comparison of Mechanical Properties of Dissimilar Steels Welded By TIG and MIG

In this review the study will be carried out on comparison of Mechanical Properties like Hardness and Strength of joints welded by TIG and MIG processes. Welding of dissimilar steels has became most common process now days in wide applications in industries. The Stainless Steel and Mild Steel joints have more applications in structural industries which provide good combination of Mechanical Properties like strength, Corrosion resistance etc. Selections of welding process for different material are difficult because of their physical and chemical properties. To obtain good quality of weld, it is necessary to select proper welding technique according to the materials selected for welding

Influence of activating flux tungsten inert gas welding on mechanical and metallurgical properties of the mild steel

Mild steels have versatile application in various structural design like in steel frame buildings, pipelines, railway wagons etc. Tungsten inert gas (TIG) welding is common to use this kind of materials. However, less depth of penetration in single weld pass make it time consuming and less productive during fabrication of thick sections (usually >3 mm). Activating flux tungsten inert gas (A-TIG) welding is growing as solution for less penetration. Successful implementation of the A-TIG welding process on mild steel could reduce the fabrication cost drastically. Therefore, in the current work, efforts are made to develop the weld joint using suitable processes/approaches. In view of above, weld joints of mild steel were developed using conventional TIG welding process and activating flux tungsten inert gas welding process. The weld joints were characterized in respect of weld bead geometry, angular distortion, microstructure, hardness distribution, tensile properties, and the impact toughness. Results have been discussed in light of microstructure study and mechanical behaviour of the weld joints.

The pores formation mechanism in the laser-MIG hybrid welded joint of mild steel

The purpose of the present study is to investigate pores formation mechanism in the laser-MIG hybrid welded joint of 20 mm thick mild steel. The microstructure and energy dispersive spectroscopy (EDS) of the welding joint are analyzed to verify the pores mechanism. Experimental results show that a well-formed weld bead can be obtained in the backing welding using a wide range of the process parameters. Besides, pores in the laser-MIG hybrid welded joints can be divided into two types, metallurgical pores, and process pores. The small, regular circle shaped metallurgical pores are generally concentrated in the upper part of the weld bead, which is mainly caused by insufficient pre-weld cleaning. In contrast, large, irregular shaped process pores are generally concentrated in the bottom of the weld bead, which is caused by the instability of the keyhole because of unreasonable welding parameters.

Effect of welding parameters on mechanical and microstructural properties of GMAW and SMAW mild steel joints

ABSTRACT This work describes welding of the sheets with different thickness values and then characterizing the mechanical and microstructural properties for two different types of welding i.e. GMAW and SMAW. The joints are devised in such pattern that the effect of sheet thickness and welding current on these properties can be easily assessed. Initial microstructural studies are carried out with high-resolution optical microscopy and SEM. These images are then processed in ImageJ software to analyze various properties of different phases involved. Mechanical properties like the tensile strength, microhardness, impact energy or toughness are also measured and correlated with the microstructures and welding parameters. The main aim of this project is to design new set of welding parameters for structural steels that are used widely in different construction works and industries. Optimizing the results and choosing the best possible way to get superior properties are the key points.

Microstructure and mechanical properties of TIG welded-brazed AZ61 Mg alloy and mild steel joints with and without interlayer

In this paper, the effects of Zn foil on the wetting ability, microstructure and mechanical properties of Mg-steel joints were investigated. TIG welding-brazing technology was performed to achieve the joining of Mg alloy and steel. The main results are shown as follows. With the applying of Zn foil, the wetting property of molten metal on solid steel plate was improved and the contact angle of Mg-steel joint decreased at the same time. The width of weld seam increased under the influence of Zn interlayer. A 2 μm thick Fe–Al reaction layer formed at the interfacial area of joint gained by directly welding of Mg-steel. However, an Mg–Zn reaction layer with the thickness of 10 μm occurred with the applying of Zn interlayer, which is the key to achieve reliable joining of Mg-steel. And the thickness of Mg–Zn layer increased with the increase of current. For the traditional TIG welded Mg-steel joint, the maximum tensile shear load is only 158 N mm−1. With the applying of Zn foil, the maximum tensile shear load of Mg-steel joint increased to 211 N mm−1 and fracture location was at the fusion area.

Retraction Note to: Effect of Process Parameters on Tensile Strength of 1018 Mild Steel Joints Fabricated by Microwave Welding

The Editor has retracted this article (1) because concerns have been raised regarding some of the figures. Figure 3 part B appears to be a copy of Figure 3 part A, with some alterations.

Nonuniformity in Mechanical Properties of Linear Friction Welded Mild Steel Joint

Mild steel was successfully joined by linear friction welding. Grain size at peripheral region was coarser than that at the other zones of the weld interface, which had no significant effect on microhardness. The local tensile properties were considerably decreased when oxides or lack of bonding appeared at the interface. Ductile fracture dominated the fracture mode for all joints. Variation in local tensile properties could be relieved under a medium friction pressure, a relatively high amplitude with a sufficient friction time. It was attributed to the facts that plastic metal layer of joint became uniform to some extent and interfacial defects were eliminated. The standard deviation of plastic metal layer thickness (χp) could be used to describe the combined effects of welding parameters on joint integral performance. It was found that the standard deviation of plastic metal layer thickness showed a strong inverse correlation with the joint integral performance. Well-formed and defect-free joints exhibiting 90% of the base metal tensile strength could be produced when processing at a frequency of 20 Hz with a friction pressure of 103 MPa or 155 MPa, an amplitude of 2.5 mm and a friction time of at least 4 s.

Effect of GMAW-brazing and Cold Metal Transfer Welding Techniques on the corrosion behaviour of Aluminium-Steel lap joints

Abstract Dissimilar metal welds of steel and aluminium find major application in automotive sector as it makes the vehicles fuel efficient. But a major concern in the Al-steel joints is the microstructural in-homogeneities in the weld zone due to the low solid solubility issues between steel and Aluminium alloy and large differences in their thermal and electrochemical properties. The durability of such welds in service environment is still an issue to be resolved. Hence the main aim of this study is to compare the corrosion behaviour of H32 5052 Aluminium-galvanized mild steel joints welded by Gas metal arc welding-brazing (GMAW-brazing) and Cold metal transfer (CMT) techniques as a function of welding parameters viz., weld speed and wire feed rate. Lap joints were fabricated using Al-5%Si filler wire, followed by the microstructural characterization using Scanning electron microscopy, hardness measurement by nano-indentor and phase analysis by X-ray diffraction technique. Corrosion testing was done on the joints following ASTM G 67-04. The results establish the effect of welding parameters on the microstructure and the corrosion behaviour of the welds. A thick Al-Fe-Si intermetallic compound (IMC) layer was formed at the weld bead-mild steel interface with Zinc entrapping in the foot region of both welds. The composition of this layer was confirmed by EDAX and XRD results. In both the cases, it had shown a severe impact on the intergranular corrosion behaviour of the welds. The results have also shown an increase in the thickness of the intermetallic layer with increase in the heat input, enhancing the galvanic and intergranular corrosion rate.

Effects of Quenchants on Impact Strength of Single-Vee Butt Welded Joint of Mild Steel

The effects of quenching medium on the impact behaviour of mild steel welded joints were investigated, single – vee butt welded joint was employed in welding the samples. The welding was carried out at 100A and at a terminal voltage of 140V (14kW), using gauge 8 coated electrode (4mm size) throughout the welding processes. Four (4) quenching media were employed which are Brine solution (0.1 Molar concentration), two (2) Litres of water, two (2) Litres of diesel oil and abundant air. 8mm thick mild steel bars were used for the heat treatment process at variable annealed temperature steps of 2000C – 4000C – 6000C. The Izod impact machine was employed in carrying out the Impact Test. The results obtained from the test carried out show that quenching in brine solution gives least average impact strength while normalized in air gives highest average impact strength and is the mildest of all the quenchants. The overall results show that air was the best medium for quenching welded mild steel followed by diesel oil, then water and lastly brine solution for quenching welded parts or components under influence of impact or sudden loading. The results will enable engineers, welding personnel and roadside welders select the best and most economic quenchant that will be best suitable for quenching welded components or parts made of mild steel subjected to impact or shocking loading.

Fatigue Strength Assessment of Welded Mild Steel Joints Containing Bulk Imperfections

This work investigates the effect of gas pores, as bulk imperfections, on the fatigue strength of welded mild steel joints. Two test series containing different butt joint geometries and weld process parameters are included in order to achieve two variable types of pore sizes. Based on the √area-parameter by Murakami, the test series can be grouped into imperfections exhibiting √area < 1000 µm and √area > 1000 µm. Fatigue tests at a load stress ratio of R = 0.1 are performed, which act as comparison for the subsequent fatigue estimation. To assess the fatigue resistance, the approaches by Murakami, De Kazinczy, and Mitchell are utilized, which highlight certain differences in the applicability depending on the imperfection size. It is found that, on one hand, Murakami’s approach is well suitable for both small and large gas pores depending on the applied model parameters. On the other hand, the fatigue concepts by De Kazinczy and Mitchell are preferably practicable for large defects with √area > 1000 µm. In addition, the method by Mitchell incorporates the stress concentration factor of the imperfection, which can be numerically computed considering the size, shape, and location of the gas pore, as presented in this paper.