Weld Material Research Articles

Effect of Ti content on weld formation and mechanical properties of welded joints of TA2/Q235 bimetallic sheets

Due to the issue of brittle Ti-Fe intermetallic compounds, a challenge for the welding of Ti/steel bimetallic sheets is presented. In this study, four types of multi-principal powders of Fe25-xCo25Ni25Cu25Tix were designed based on eutectic high-entropy alloys (HEAs), which were used as filler materials for laser welding of TA2/Q235 bimetallic sheets. The impact of Ti content in the filler powders on weld formation and mechanical properties was investigated. It is found that with an increase in the Ti content, the hardness values of the weld zones generally increased, whereas the tensile strengths decreased. The maximum tensile strength of ∼298.4 MPa was achieved in the joint using Fe20Co25Ni25Cu25Ti5 filler powders, in which the weld metal met the definition of an HEA.

The Use of Thermal Data for Quality Assurance in the Process of Continuous Ultrasonic Welding of Thermoplastic Composite Materials

Continuous ultrasonic welding (CUW) is a manufacturing process used to join thermoplastic composite materials using high-frequency ultrasonic vibrations. Under pressure and vibration, the welding material heats up, melts and the welding partners are joined while they are cooling down. The development of CUW is getting raised attention over the last decade since the use of thermoplastic composites (TCs) in the production industry and especially the aerospace sector demands for economic and fast joining techniques. In order to establish this welding technique in the industry it is necessary to develop methods which enable to do quality assurance on the produced welding seams. In the experiments described in this paper the potential of thermal measurements for the quality assurance of the ultrasonic welding of TCs is investigated. Different thermal systems are evaluated and it is described how the data of the most promising technique is further processed and fed to an artificial intelligence (AI) algorithm. The here trained networks are created to predict lab-shear-strength values and reach mean absolute error scores of below 1 MPa. The described investigations hint that thermography seem to be a valuable resource to make more reliable quality assurance in the process of CUW of TCs and therefore might help to establish the use of this welding technology further in the industry.

P‐99: A New Unit‐cell Type Fine Metal Mask for IT & Gen8.x AMOLED Applications

In this study, we explore the feasibility of employing a unit‐cell type fine metal mask (uc‐FMM) for IT and Gen8.x AMOLED applications, which currently represent the forefront of the OLED industry in the upcoming era. The conventional stick‐type fine metal mask (FMM) raised concerns about lateral wrinkling with increasing mask width, particularly affecting middle and large‐sized displays and the overall panel efficiency of glass design. Our focus lies in understanding the tension relationships within the mask and the open mask used as a sub‐frame for support. The tensions involved—T1 for the metal mask, T2 for the open mask, and T3 at the welding points—all play crucial roles. We utilized portable X‐ray diffraction (XRD) to measure these tensions accurately. Of particular significance is T3, which we analyzed in relation to welding morphology, welded adhesion, and material properties. By experimenting with different invar materials and welding lasers, we established quantitative relationships. Our findings strongly indicate that uc‐FMM presents a compelling and inevitable solution for the future of OLED technology.

Experimental investigation on microstructure, hardness and corrosion resistance of an electromagnetic welded titanium-stainless steel dissimilar materials

The electromagnetic welding (EMW), often known as magnetic pulse welding, is a solid-state welding technology that is used to join two different materials using high-velocity impact. In this study an attempt was made to join the Titanium(Ti)- Stainless Steel(SS 304) materials with the help of multi turn disc coil along with the field shaper. A comparative investigation was conducted on the joint’s microstructure, as well as its mechanical and corrosion properties. Inverted optical microscopy (OM) and x-ray diffraction (XRD) were used to do the microstructural characterization of the joint. The micro-Vickers hardness test was used to analyse the material’s mechanical properties. In addition, electrochemical experiments were run on the Ti-SS 304 EMW junction as well as the component materials to establish how resistant they were to corrosion. Using an electrochemical impedance analyzer, the levels of corrosion that were caused by the structures were measured while they were submerged in a solution of nitric acid at room temperature. The microstructural pictures revealed a wave-like pattern at the material’s interface, which is evidence of strong adhesion between the components. The micro vickers hardness of the joints was within the permitted range, as was the corrosion rate.

Research on the welding process of Q355ND thick plate with narrow gap double wire submerged arc welding

Abstract Aiming at the problems of low welding efficiency and unstable quality of thick plates of marine equipment in offshore deep-water areas represented by offshore wind power, the high-efficiency welding process of narrow-gap double-wire submerged arc welding of 30 mm thick Q355ND low alloy high-strength steel plate was developed by selecting the suitable welding material and welding process parameters. The results show that the welded joint has a beautiful appearance, well-fused sides, and no defects. The structure of the heat-affected zone of the joint is mainly composed of pro eutectoid ferrite, acicular ferrite, bainite, and a small amount of pearlite. The center of the seam is composed of a large amount of massive ferrite and a small amount of bainite. The average tensile strength of the joint reaches 536.5 Mpa, and the average impact energy of the weld center at -20°C reaches 48.4 J. The average impact energy of the heat-affected zone reaches 164 J. All physical and chemical performance tests meet the standard requirements. The development of welding processes has important practical significance for improving production efficiency and product quality. It will be widely used to construct offshore wind power towers, offshore platform jackets, and other offshore deep-water engineering equipment.

Research on the residual stress of stainless steel pipe after overlay repair

The weld overlays are widely used to repair metal butt welds or piping components by depositing weld metal on the outside surface of the welds and piping components. This paper presents the detailed residual stress distribution of girth weld in stainless steel pipe after butt welding and weld overlay repair by using finite element analysis. Two dimensional (2D) cross-section models, axisymmetric assumptions for piping girth welds are used to simulate the welding process in order to predict the residual stress distribution in the weld and base material. A project has been implemented to validate the analytical models used to perform welding residual stress analysis against measured residual stresses data in literature. It is found that the simulation results of butt welding are consistent with the experimental results in literature, which means that the analysis model and its results are accurate and reliable. A series of simulations are conducted to investigate the changing rules of influencing factors of overlay repair for stainless steel pipe. The results show that appropriate interpass temperature and heat input, increasing the thickness of overlay can effectively increase the range of compressive stress in pipe, so as to prevent and limit the generation and propagation of cracks. This research may provide an important support for the formulation of weld overlay repair standards in service.

Selected properties of X120Mn12 steel welded joints by means of the plasma-MAG hybrid method

The article describes properties of welds made of high wear resistance X120Mn12 steel obtained by the hybrid PTA-MAG (plasma transferred arc – metal active gas) method. The specimens were 8 mm thick rectangular (200 mm × 350 mm) sheets metal. The analyzed butt welds were made with the parameters selected according to the criterion of smallest cross-sectional area of welds and the narrowest HAZ (heat affected zone). The outcome of metallographic tests of weld, HAZ and parent material, hardness distribution and XRD (X-ray diffraction) patterns of selected areas are presented. The IIT (Instrumented Indentation Test) method was used to describe the distribution of mechanical properties shaped by thermal cycle annealing of the welding process. The investigation shows that the application of the PTA-MAG hybrid heat source for welding manganese steel enables the use of the filler material ER307 (AWS-A5.9). The hybrid PTA-MAG welding system has the relatively high potential to be an efficient alternative to welding standard processes for X120Mn12 steel due to the HAZ overheating limitation. The zone of high-risk weld cracking is the part of the HAZ close to the fusion area that has been reheated during weldment formation. Heat input about 0.6 kJ/mm is needed to provide full deep penetration butt weld without defects and with a vapor capillary of wide enough to cover the weld gap. The increase of hardness in the welded joint is smooth distributed and going up to 10% compared to the base material. The width of HAZ was <1 mm. Intensive carbides precipitation in HAZ has been avoided successfully.

Circular economy as applied to refractory materials.

The closed-loop economy concerning refractory materials is implemented through systematic involvement in post-operational usage in thermal, including metallurgical, units as secondary (by-product) raw materials. This is one of today's trends in resource and energy economics, reducing carbon footprint and CO2 emissions, decreasing waste with subsequent disposal in landfills. Purified scrap of refractory materials is used as supplementary materials in metallurgical processes, commonly referred to as scrap utilization when used as fluxes to adjust slag composition in metallurgical units, molded materials for welding in converters, refractory fillers in the production of unformed materi-als for sections lining working outside the aggressive influence of molten metal and slag, etc. For these purposes, the scrap is sorted into grades, crushed and screened, occasionally incorporating other products. Refractory scrap after ser-vice in metallurgical units usually has higher impurity content, higher porosity, and contains fragmented remnants of the refractory structure. Recycling refractory scrap may additionally involve technological methods for extracting impurities (enrichment) with subsequent use of the recyclate directly in refractory production, partially replacing primary raw materials. In this case, research work with involvement of qualified specialists and the entire body of knowledge in creating new refractory materials is necessary. Practice has shown that qualified involvement of recyclate in manufacturing processes of high-quality refractories is accompanied by solving non-standard tasks and requires a special approach, including the issue of removing introduced or formed foreign materials in refractory material during its operation. Enrichment is an effective direction for cleaning refractory scrap, extracting quality materials during processing of waste from mining enterprises, materials of technogenic origin to obtain recyclate of necessary quality. The enrichment technology is selected based on the set tasks. Recyclate quality for use alongside primary raw materials must guarantee refractory manufacturers meet the corresponding requirements of end-users. An original technology of recyclate enrichment during its selective grinding with product separation using air-gravitational and centrifugal-air classification has been developed

Circular economy as applied to refractory materials

The closed-loop economy concerning refractory materials is implemented through systematic involvement in post-operational usage in thermal, including metallurgical, units as secondary (by-product) raw materials. This is one of today's trends in resource and energy economics, reducing carbon footprint and CO2 emissions, decreasing waste with subsequent disposal in landfills. Purified scrap of refractory materials is used as supplementary materials in metallurgical processes, commonly referred to as scrap utilization when used as fluxes to adjust slag composition in metallurgical units, molded materials for welding in converters, refractory fillers in the production of unformed materi-als for sections lining working outside the aggressive influence of molten metal and slag, etc. For these purposes, the scrap is sorted into grades, crushed and screened, occasionally incorporating other products. Refractory scrap after ser-vice in metallurgical units usually has higher impurity content, higher porosity, and contains fragmented remnants of the refractory structure. Recycling refractory scrap may additionally involve technological methods for extracting impurities (enrichment) with subsequent use of the recyclate directly in refractory production, partially replacing primary raw materials. In this case, research work with involvement of qualified specialists and the entire body of knowledge in creating new refractory materials is necessary. Practice has shown that qualified involvement of recyclate in manufacturing processes of high-quality refractories is accompanied by solving non-standard tasks and requires a special approach, including the issue of removing introduced or formed foreign materials in refractory material during its operation. Enrichment is an effective direction for cleaning refractory scrap, extracting quality materials during processing of waste from mining enterprises, materials of technogenic origin to obtain recyclate of necessary quality. The enrichment technology is selected based on the set tasks. Recyclate quality for use alongside primary raw materials must guarantee refractory manufacturers meet the corresponding requirements of end-users. An original technology of recyclate enrichment during its selective grinding with product separation using air-gravitational and centrifugal-air classification has been developed

Study of The Microstructure and Mechanical Property Relationships of Gas Metal Arc Welded Dissimilar Protection 600T, DP450 and S275JR Steel Joints

The need for combining dissimilar materials is steadily increasing in the manufacturing industry, and the resulting products are expected to always have high performance. While there are various methods available for joining such material pairs, one of the commonly preferred techniques is fusion welding. In this study, three different steel materials (Protection 600T, DP450, and S275JR) were joined using gas metal arc welding (GMAW) in different combinations (similar/dissimilar). The microstructure and mechanical properties of the joints were evaluated. Tensile test, Vickers microhardness (HV 0.1), bending, Charpy V-notch impact testing, and microstructure examinations were conducted to analyze the weld and heat-affected zone. The tensile strengths of the base metal materials Protection 600T, DP450, and S275JR were found to be 1524.73 ± 18.7, 500.8 ± 10.4, and 508.5 ± 9.5 MPa, respectively. In welded samples of similar materials, the highest efficiency was found to be 103.05% for DP450/DP450, while in dissimilar welded joints, it was 105.5% for the DP450/S275JR pair. Hardness values for the base materials Protection 600T, DP450, and S275JR were measured as 526.5 ± 10.5, 153.8 ± 1.8, and 162.5 ± 5.2, respectively. In all welded samples, there was an increase in hardness in the weld zone (due to the welding wire) and the heat-affected zone (due to grain size refinement). While the impact energy values of similar material pairs were close to the base material impact energy values, the impact energy values of dissimilar material pairs varied according to the base materials. In addition, in joints made with similar materials, the bending force was close to the base materials, while a decrease in bending force was observed in joints formed with dissimilar materials. As a result, the welding of DP450 and S275JR materials was carried out efficiently. Protection 600T was welded with other materials, but its welding strength was limited to the strength of the material with low mechanical properties.

Comparison of fatigue crack growth design curves on GMAW and EBW joints of high strength steels

There is a growing demand in the industrial sector for the use of high-strength structural steels (HSSSs), which can achieve a significant weight reduction in structures. These structural steels are usually produced by quenching and tempering (Q + T) or thermomechanical treatment (TM), and their applications in welded structures pose several challenges for the users. In industrial practice, gas metal arc welding (GMAW) is basically the most commonly used fusion welding process, which has a relatively high heat input. However, at HSSSs, there is a need for low heat input but, at the same time, productive welding processes. High-energy density welding processes, e.g., electron beam welding (EBW), offer a unique opportunity to weld these steels. The widespread use of HSSSs is also hampered by the fact that the benefits of high strength can be exploited primarily under static loading. At the same time, different welded structures made of HSSSs are often subjected to cyclic loading, and possible weld defects and material discontinuities are major risks in this case. During our experiments, GMAW and autogenous EBW processes were applied to make welded joints from S960 Q + T and TM structural steels. The fatigue resistance of the welded joints was characterized by fatigue crack growth (FCG) tests, considering the increased crack sensitivity of HSSSs. A statistical approach was followed both in the design of the experiments and in the evaluation of their results. Based on the test results fatigue crack propagation design curves were determined for the investigated GMAW and EBW welded joints. The design curves were compared with each other, with design curves of lower strength material (S690QL) and with the recommended fatigue crack growth laws of BS 7910.

Study on the tensile properties and deformation mechanism of high-temperature resistant nitrogen-containing nickel-based welding material deposited metal

This article uses a new type of nitrogen-containing nickel-based flux cored welding wire as the experimental material to study the tensile properties and deformation mechanism of the deposited metal from room temperature to 900 °C. The results show that the tensile strength gradually decreases with the temperature. The plasticity gradually increases, but the lowest value appears at 700 °C, which is the phenomenon of intermediate temperature brittleness. M23C6 carbides begin to decompose at 700 °C. More carbonitrides are precipitated within the crystal with temperature. In the low-temperature zone (T ≤ 600 °C), the main deformation mechanism is the unit dislocation a/2<110> cutting precipitation phase. In the medium-temperature zone (600 °C < T ≤ 750 °C), initiation of Orowan bypass mechanism for dislocations. In the high-temperature zone (800 °C ≤ T ≤ 900 °C), the slip and climbing mechanism of dislocation is the main deformation mechanism.

Characterisation of a New Generation of AlMgZr and AlMgSc Filler Materials for Welding Metal–Ceramic Composites

When manufacturing the welded joints of components made of metal–ceramic composites of the Al-Si/SiC type, we encounter significant difficulties. This is related to the presence of a ceramic phase in the aluminium alloy matrix. The interaction between the molten metal matrix and the ceramic particles in the weld pool influences a complex of physicochemical phenomena resulting in, among other things, the structure of the welded joint. This is particularly true of the effect of the distribution of ceramic particles and their influence on the crystallisation process in the weld pool. An important issue is the influence of the reinforcing particles on the susceptibility of the aluminium matrix to both hot and cold cracking. The scope of the research included the development of the chemical composition of an additive material for the TIG welding of aluminium–ceramic composites. This material was made in the form of so-called sticks, cast from alloys containing elements such as magnesium, scandium or zirconium in addition to aluminium. The appropriate composition of the mass content of the individual components was intended to change the crystallisation mode of the weld pool and to obtain strengthening precipitates. The most favourable structure was obtained in the case of a modification of the AlMg5 alloy by the addition of scandium. Minor dispersions of Al3Sc became the nucleation pads of fine grains, which improved the mechanical properties of the alloy. Also, in the case of the addition of zirconium, the crystallisation shifted from dendritic to fine-grain growth. In this paper, the basic strength properties of the developed materials were tested and the most favourable chemical compositions of the filling materials were selected.

Corrosion behavior of austenitic stainless steel and nickel-based welded joints in underwater wet welding

Marine structures such as ports, bridges, pipelines, vessels, and platforms are an essential part of modern infrastructure, where the use of higher-strength steel provides savings in logistics and construction. However, the repair of higher-strength steels can be challenging, especially underwater. Wet shielded metal arc welding is the most widely used and least expensive method for underwater welding repairs, but is very susceptible to hydrogen-induced cracking. Thus, researchers and welding engineers aim to reduce the amount of hydrogen in the weld material. Recent success has been achieved through the use of austenitic welding consumables, such as austenitic stainless steel and nickel-based electrodes. The use of these consumables drastically reduces the amount of diffusible hydrogen in the weld metal. However, these austenitic materials usually have different corrosion potential as compared to the structural steel the weld beads are applied to. This creates the risk of severe galvanic corrosion. In the presented study, the corrosion behavior of welds created with austenitic stainless steel and nickel-based electrodes were studied. Samples were aged for 1.5 years in the Baltic Sea. Simultaneously, the effectiveness of corrosion protection systems such as coating and Impressed Current Cathodic Protection (ICCP) were evaluated. Localized corrosion occurred in the heat-affected zone when austenitic electrodes were used in the corrosive environment. The localized corrosion depth after 1.5 years in the Baltic Sea and in the salt spray layer was approximately 250 µm and 390 µm, respectively. The ICCP system and the use of a coating were effective in preventing localized corrosion. The low pitting corrosion density of 2.5 × 103 m−2 corresponds to grade A1 according to the standard and was found to be negligible as compared to the localized corrosion in the heat-affect zone.

Determination of optical properties of single crystal diamond substrates grown via welding-assisted microwave plasma enhanced chemical vapour deposition

Lab grown single crystal diamonds (SCDs) offer unrivalled hardness, a wide range of optical transparency, and supremely high thermal conductivity reliable materials to be a part of devices run at high frequency, temperature, and power. Effective synthesis techniques are essential in enhancing the potential applications of high-quality SCDs. This study aims to decrease the thermal contact resistance between diamond seeds and the molybdenum holder by utilizing welding material. Quality of grown diamond substrates (plates) were assessed by analysing optical properties through Raman, UV-Vis, and FT-IR spectroscopic methods. The findings revealed that the grown single-crystal diamonds have excellent transmittance (>70%) and absorption at 270 nm. Calculations also showed an average absorption coefficient of 1.1 cm−1, indicating the high quality of the grown SCDs with nitrogen impurities below 10 ppm. The absorption observed in the FTIR spectra, ranging from 1600 cm−1 to 2700 cm−1 with a peak at 2354.13 cm−1, is referred to as the “two phonon region,” which is a distinctive feature of the diamond phase.

Enhancement mechanism of shear properties for SiO2 ceramics by laser welding with Al2O3/SiO2 powder

The laser direct fusion welding of SiO2 ceramics was a global challenge in the manufacture of radome. The paper explored the laser direct fusion welding of SiO2 ceramics, investigated the influence of filling powder addition and welding material composition on the formation of weld. The findings revealed that the addition of welding material effectively addressed the issue of weld formation in laser direct fusion welding SiO2 ceramic. However, the abundance of internal bubbles within the weld emerged as a significant impediment to further enhancing weld strength. The addition of SiO2/Al2O3 mixed powder not only significantly reduced the quantity and size of internal bubbles within the weld but also generated the strengthening phase Al2SiO5, leading to a substantial increase in weld shear strength, reaching a maximum of 106 % of the base material. The research results provided a new solution for direct melting welding of ceramics.

Friction welding of UFG copper using the W2Mi prototype machine

When welding ultra-fine-grained metals using conventional methods, the microstructure in the joint area is degraded (mainly due to recrystallization) in the heat-affected zone and a significant deterioration of mechanical properties, including joint strength. The aim of the research presented in this article was to identify the possibility of obtaining joints with strength close to initial material using friction welding of metal materials with ultra-fine grain. For this purpose, UFG (ultra-fine-grained) material was produced from technically pure M1Ez4 copper using a hybrid SPD (severe plastic deformation) process. The welding process was carried out on a machine with a prototype design that allows minimizing the welding time, while generating high force. The process parameters used on the prototype machine resulted in an increase in the hardness of the material by 4% in the joint area. The strength of the joint compared to the base material decreased slightly by 2%. The tests carried out proved that, using appropriate process parameters, it is possible to obtain a UFG metal joint without a decrease in its mechanical strength.

Enhanced strength and ductility of aluminum alloy laser welded joints through Ca micro˗alloyed welding materials

Aluminum alloy is widely used in high˗speed train bodies. However, compared with the base material, the tensile strength and elongation of its laser welded joints are significantly reduced, which limits the lightweight application of the next generation of high˗speed trains. The research in this article indicates that laser welding with Ca micro˗alloyed 5356 filler metal has changed the mechanical properties and microstructure of the weld seam. Without the Ca in the filler metal, the strength and elongation of the laser welded joint are only 215.5 MPa and 3.1 %. When the Ca content in the filler metal reaches 0.04 wt%, the laser welded joint has high tensile strength and maximum elongation, which are 251.5 MPa and 9.7 %, respectively. As the Ca content increases, the grain size of the welded joint gradually decreases, and the limiting effect of Ca element on the growth of α˗Al grains is the main reason for grain refinement. In addition, the addition of Ca transforms the coarse Fe˗rich phase in the weld into a fine˗grained second phase, while promoting the formation of deformable nanoparticles γ˗Al12Mg17, leading to the accumulation of dislocations and successfully improving the strength and plasticity of laser welded joints. When the Ca content further increases, the second phase grows, and the tensile strength and plasticity of the joint slightly decrease, but are still higher than that of the joint without Ca.

A study on effect of laser overlay welding parameters of stainless steel 301 LN: tensile test, microstructure analysis and microhardness evaluation

This study investigates the effects of laser overlay welding parameters on the performance of stainless steel 301 LN. The correlation between welding conditions and material characteristics was explored through systematic experiments involving tensile testing, microstructure analysis and microhardness evaluation. The study reveals that optimizing welding parameters, such as laser power, laser speed and oscillation amplitude, significantly enhances both the mechanical strength and microstructural features of stainless steel 301 LN. The results show the maximum strength was achieved using a power of 3 kW, 2 m/min speed, oscillation amplitude of 1.5 mm and focal position of 6 mm. The microhardness results displayed a significant drop in the centre of the welded zone due to thermal dynamics. Additionally, the findings of fractography results highlighted how minimum and maximum welding parameters affect the fracture characteristics and integrity of welded joints. The study also revealed a complex range of microstructures, including skeletal, vermicular and lathy ferrite formations. The microstructural images provide valuable insights into the size and distribution of lathy ferrites, and the transformation of delta-ferrite to austenite, contributing to a comprehensive understanding of the welding process. Overall, this research contributes to the ongoing efforts to refine manufacturing processes and applications for stainless steel.

Two fatigue fracture modes at different temperatures of 10%Cr heat-resistant steel weldment filled with Ni-based alloy

9–12%Cr heat-resistant steels are widely used as ultra-supercritical thermal power generation components for their excellent high temperature performance and economic applicability. In order to overcome the problems of welding cracking and carbon migration of 9–12%Cr heat-resistant steels’ welded joints, Ni-based alloy welding materials are being more and more widely used. However, a very distinct interface will form between 9–12%Cr heat-resistant steels and Ni-based alloy welding materials due to their different chemical compositions and microstructures. In this work, the microstructure of the interfacial transition zone between a 10%Cr heat-resistant steel and Ni-based alloy welding material is investigated. The influence of temperatures on the fatigue behavior of the welded joint is studied. Two fatigue fracture modes at different temperatures are found, and the underlying mechanism of the different fracture modes are discussed in detail.