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Gas tungsten arc welding-tungsten inert gas (GTAW-TIG) is focused in literature as an alternative choice for joining high strength low alloy steels; this study is performed to compare the differences between gas metal arc welding-metal inert gas (GMAW-MIG) and GTAW welding processes. The aim of this study is to characterize microstructure of dissimilar transformation induced plasticity steels (TRIP) and martensitic welded joints by GMAW and GTAW welding processes. It was found that GMAW process lead to relatively high hardness in the HAZ of TRIP steel, indicating that the resultant microstructure was martensite. In the fusion zone (FZ), a mixture of phases consisting of bainite, ferrite and small areas of martensite were present. Similar phase’s mixtures were found in FZ of GTAW process. The presence of these mixtures of phases did not result in mechanical degradation when the GTAW samples were tested in lap shear tensile testing as the fracture occurred in the heat affected zone. In order to achieve light weight these result are benefits which is applied an autogenous process, where it was shown that without additional weight the out coming welding resulted in a high quality bead with homogeneous mechanical properties and a ductile morphology on the fracture surface. Scanning electron microscopy (SEM) was employed to obtain information about the specimens that provided evidence of ductile morphology.

Duplex stainless steels are commonly used for various applications owing to their superior corrosion resistance and/or strength. They have ferromagnetic behavior together with a good thermal conductivity and a lower thermal expansion as a result of higher ferrite content than austenitic steels. Their ferrite matrix suffers a decomposition process during aging in the temperature range 650-950° C producing precipitation of austenite, σ and χ, carbides and nitrides. These intermetallic phases are known to be deleterious for corrosion resistance and mechanical properties.In this work the effect of aging time during isothermal treatment at 850°C and 900°C on the microstructure of SAF 2205 Duplex Stainless Steels welded plates has been investigated. The aim of this work is to determine the morphology of σ phase, and perform a quantitative analysis of the precipitation process.Submerged Arc Welding is used for processing. It produces a high content of δ ferrite in the heat affected zone and low content of austenite in the weld. Microstructural examination shows that the σ phase precipitates at δ ferrite/γ interphases. Longer aging treatments give rise to an increase of volume fraction together with a coarser morphology.

Heat input during welding metal fusion generates different transformations, such as grain growth, hydrogen cracking, and the formation of brittle structures, generally associated with the heat-affected zone (HAZ). For this reason, it is very important to know the behavior of this area before welding. This paper presents a study of the thermal behavior and its effect on phase transformations in the HAZ, depending on cooling rates (0.1–200 ∘C/s) to obtain continuous cooling transformation (CCT) curves for an high-strength low-alloy (HSLA) steel. In order to determine the formed phases, optical microscopy and Vickers microhardness measurement were used. The experimental CCT curve was obtained from an HSLA steel, and the results showed that, with the used cooling conditions, the steel did not provide formation of brittle structures. Therefore, it is unlikely that welds made by submerged arc welding (SAW) may lead to hydrogen embrittlement in the HAZ, which is one of the biggest problems of cracking in gas conduction pipelines. In addition, with these results, it will be possible to control the microstructure to optimize the pipe fabrication with SAW process in industrial plants.

The aim of this investigation is to evaluate the distortions generated in welding unions of stainless steel 304 by effect of the welding temperature and the microestructural changes. The joint design is a 100 × 100 mm steel plate of 3 mm thickness. The plate was joined to a tube of 50 mm diameter and 2 mm thickness, which has a defined angular cut; therefore, the trajectory followed by the seam has an elliptic form. Temperature data acquisition was developed by type K thermocouples, placed in pairs at 0∘, 90∘, 180∘ and 270∘ along the welding trajectory and connected to a data acquisition device yo obtain the measures to generate time-temperature plots. The welding process was executed by a KUKA®; KR16 welding robot with an integrated GMAW (Gas metal arc welding) process where the input parameters of voltage, wire feed and travel speed are set to constant. The distortion of the work piece was measured using a laser scanning technique that generates a point cloud with the VXelements TM software for comparison between the pre and post-weld condition. Microstructural evaluation was performed on transversal sections of the seam, at the mentioned angles for correlation.

Automotive and aerospace industries are maintaining constant development and innovation, demanding for materials that can fulfill emissions, fuel efficiency, and security regulations. Recently, the interest in automotive applications of metal matrix composites (MMC) is increasing. MMC exhibits excellent mechanical properties such as wear and abrasion resistance, high strength, chemical stability, and dimensional stability to high temperatures. In order to join MMC, friction stir welding (FSW) appears as the most promising joining process compared with conventional fusion welding processes, mainly for the ability to join without compromising their ceramic reinforcements. The aim of this study was to evaluate the microstructural changes of diverse parameters of aluminum matrix reinforced with 20 % wt. Al/SiC composite was welded with different process parameters such as tool rotation speed and axial force using FSW. In order to determine the different microstructural zones characterization of the samples was carried out by optical microscopy (OM) and scanning electron microscopy (SEM). In addition, an evaluation of mechanical property such as microhardness of the different zones of the joint in the aluminum matrix composite samples was performed.

Manufacturing in almost all industries involves joining together many components. Welding is the most popular joining process, which is cost effective, reliable, and versatile. In the automobile industry, when welding is applied, distortion can occur and produce additional costs of rework. Distortion became a potential problem in this process, since the joint undergoes significant thermal expansion and contraction, longitudinal and transverse shrinkages and leads to a non-desired welded structure. Recently, the usage of more lighted alloys in automobile sector ensures the conductor’s safety and reduction of emission; stainless steels have been placed in this industry as a compelling alternative for some carbon steels.

Today, stainless steel is widely used in automotive industry due to its high impact resistance, corrosion resistance and light weight. This paper present the research carried out to study the differences between microstructure and mechanical properties of 409 and 308 stainless steel sheets, each joints by gas tungsten arc welding (GTAW). For each of weldments, detailed analysis was conducted on the chemical composition, microstructure characteristics and mechanical properties of base metal (BM), heat affected zone (HAZ) and fusion zone (FZ). Scanning electron microscopy (SEM) and optical microscopy were used to analyze microstructural changes and mechanical properties, including microhardness and tensile test. This study can be a practical guide in the selection of other materials in order to determine the important to use in structural automotive industry.

Environmental, concerns regarding reducing CO2 emissions and the drive of having better fuel economy have already enthused the car manufacturer to use the weight materials having better mechanical properties. Automotive industry has shown a great interest in Dual Phase steels due to the possibility of reducing weight of vehicles and increasing the passenger safety at a very competitive cost. Automotive applications unavoidably entail welding and joining in the manufacturing process and the fatigue resistance of welded joints due to the integrity and safety requirements. The variation of welding parameters (voltage, current and speed of welding) affects weld performance, mechanical, and metallurgical properties.The CMT (Cold Metal Transfer) braze welding is a relatively new technology that partially decouples the arc electrical transients from the filler wire feed rate. It allows reducing the heat required for welding and permits higher joining speeds.The aim of this work is to study the interfacial microstructures and intermetallic compounds produced by cold metal transfer welding of two plates of galvanized DP600 dual phase steel with CuSi3 as filler metal. The study was performed by applying a CMT braze welding with three different joining speeds. The welded microstructures and microhardness were determined and related to the welding process conditions.A small HAZ, constituted by martensite, bainite and coarse ferrite grains, has been highlighted. Furthermore, an intermetallic Fe-Si-Cu compound layer formed at the interface between steel and filler metal. The joining speed sways the size of ZTA since the heat input Q affects the phase transformation in the weld and heat affected zoneThis parameter also affects the thickness of the compound layer and the size of precipitates in the filler metal, likewise the mechanical characteristics. The fracture starts at the interface steel-copper where intermetallic compounds formed.