Showing papers on "Filler metal published in 2022"

Microstructure and mechanical properties of gas metal arc welded CoCrFeMnNi joints using a 410 stainless steel filler metal

Abstract: The use of filler materials during fusion-based welding processes is widely used to regulate and modify the composition of the welded joints aiming at producing a desired microstructure and/or achieving an improvement in its mechanical performance. Welding of high entropy alloys is still a new topic and the impact of different filler materials on the microstructure and mechanical properties is yet unknown. In this work, gas metal arc welding of the CoCrFeMnNi high entropy alloy using 410 stainless steel as a filler wire was performed. The microstructural evolution of the welded joints was evaluated by optical microscopy, scanning electron microscopy aided by electron backscattered diffraction, high energy synchrotron X-ray diffraction and thermodynamic calculations. Meanwhile, the mechanical behavior of the welded joint, as well as the local mechanical response were investigated with microhardness mapping measurements and with non-contact digital image correlation during tensile loading to failure. The weld thermal cycle promoted solid state reactions in the heat affected zone (recovery, recrystallization and grain growth), which impacted the microhardness across the joint. The role of the 410 stainless steel filler material in the solidification path experienced by the fusion zone was evaluated using Scheil-Gulliver calculations, and a good agreement with the experimentally observed phases was observed. Despite the addition of the 410 stainless steel filler was not conducive to an increase in the fusion zone hardness, the associated bead reinforcement promoted an improvement in both the yield and tensile strengths of the joint compared to a similar weld obtained without filler material (355 vs 284 MPa and 641 vs 519 MPa, respectively). This allows to infer that the addition of filler materials for welding high entropy alloys is a viable method for the widespread use of these novel materials. In this work, by coupling microstructure and mechanical property characterization, a correlation between the processing conditions, microstructure and mechanical properties was obtained providing a wider basis for promoting the application of gas metal arc welding of high entropy alloys for industrial applications. • Gas metal arc welding using 410 stainless steel filler wire to join a CoCrFeMnNi high entropy alloy was performed. • Recrystallization followed by grain growth were the primary causes behind heat affected zone softening. • Existing phases predicted by thermodynamic calculations were in good agreement with those observed at the fusion zone. • Stress concentration at the weld toe is a dominant factor contributing to failure of welded joints. • Suitability of using filler materials for joining CoCrFeMnNi high entropy alloys is demonstrated.

Porosity, microstructure and mechanical property of welded joints produced by different laser welding processes in selective laser melting AlSi10Mg alloys

Abstract: The welding process has been recently introduced to join of the materials fabricated by powder bed fusion (PBF) additive manufacturing (AM) to meet the requirement for the large parts and their repair in service. However, one of the main issues is the high susceptibility to the hydrogen pores occurred during fusion welding of the PBF aluminum (Al) alloys. Autogenous laser welding of a selective laser melting (SLM) AlSi10Mg alloy was firstly carried out in comparison with the casting AlSi10Mg alloy to examine the hydrogen pore characteristics. Single-pass welding with filler powders and laser melting deposition (LMD) welding were then performed on SLM AlSi10Mg alloys to reduce the hydrogen pores. The porosity, microstructure, microhardness and tensile property of the welded joints were investigated. As a result, a high susceptibility to hydrogen pores of SLM AlSi10Mg alloys is occurred in the weld metal (WM) of the welded joint produced by autogenous laser welding and single-pass laser welding due to the high hydrogen content pre-existing in the base metal (BM). However, LMD welding has been shown to effectively reduce the pore size and the porosity generated in the WM of SLM AlSi10Mg alloys. The laser welding of SLM AlSi10Mg alloys produces lower hardness and ultimate tensile strength (UTS) than that of the BM. However, the LMD welding of SLM AlSi10Mg alloys achieves higher hardness and UTS than those of the autogenous laser welding and single-pass laser welding, which is attributed to the refined microstructures and the reduced hydrogen pores in the WM.

Experimental Investigation of Effect of Welding Parameters on Surface Roughness, Micro-Hardness and Tensile Strength of AISI 316L Stainless Steel Welded joints using 308L Filler Material by TIG Welding

Abstract: Tungsten inert gas (TIG) welding is type of arc welding with area of applications in food industry, pharmaceutical industry, chemical plants, marine, aerospace, medical devices, and implants, etc. TIG welding process involve several parameters. Many parameters are controllable by the operator, and these parameters have a direct or indirect impact on the microstructure and mechanical properties of the joints. In the present study, three TIG welding parameters, arc current, voltage, and shielding gas flow rate, were changed up to three levels and their effects on surface roughness, hardness and tensile strength were investigated. Experiments were carried out on a 3 mm thick plate of austenitic stainless steel AISI 316L utilizing a TIG welding equipment and were designed according to Taguchi L9 orthogonal array (OA). ER308L was used as filler material. Results were analyzed using signal to noise S/N ratio and analysis of variance. It was observed that, for optimization of each response, arc current is the most influential factor. Minimum surface roughness was achieved at parametric combination of current 125 A, voltage 18 V and gas flow rate 12 L/min. Maximum hardness was achieved at parametric combination of current 125 A, voltage 20 V and gas flow rate 9 L/min. Maximum tensile strength was achieved at parametric combination of current 100 A, voltage 18 V and gas flow rate 6 L/min.

Advanced High-Strength Steels for Automotive Applications: Arc and Laser Welding Process, Properties, and Challenges

Abstract: In recent years, the demand for advanced high-strength steel (AHSS) has increased to improve the durability and service life of steel structures. The development of these steels involves innovative processing technologies and steel alloy design concepts. Joining these steels is predominantly conducted by following fusion welding techniques, such as gas metal arc welding, tungsten inert gas welding, and laser welding. These fusion welding techniques often lead to a loss of mechanical properties due to the weld thermal cycles in the heat-affected zone (HAZ) and the deposited filler wire chemistry. This review paper elucidates the current studies on the state-of-the-art of weldability on AHSS, with ultimate strength levels above 800 MPa. The effects of alloy designs on the HAZ softening, microstructure evolution, and the mechanical properties of the weld joints corresponding to different welding techniques and filler wire chemistry are discussed. More specifically, the fusion welding techniques used for the welding of AHSS were summarized. This review article gives an insight into the issues while selecting a particular fusion welding technique for the welding of AHSS.

The effect mechanism of Zn, Ni and Mn solute elements on the WC/Cu-based filler metal interfacial properties: First-principles calculations and experiments

Abstract: In this work, the first-principles calculation was performed to investigate the effect mechanism of Zn, Ni and Mn solute elements on the WC/Cu-based filler metal interfacial properties, and the CuZnNiMn filler metal was designed, the diffusion behavior of interface elements was verified by experiments. Firstly, Zn, Ni and Mn element doping WC/Cu interface models were established respectively. The effect natures of alloying elements on the interfacial properties were explored by adhesive strength and interfacial electronic structure. The results show that Zn element slightly aggregate into the Cu matrix interior after full relaxation, which has little effect on the interface structure, but it can lower the melting point and optimize the properties of Cu-based filler metals. Ni, Mn elements tend to segregate toward the interface and form strong covalent bonds and metallic bonds with W atoms, which can significantly improve the interfacial bonding strength of WC/Cu. The Energy Dispersive Spectroscopy (EDS) analysis of the WC/CuZnNiMn interface region proves that the diffusion effect of Zn in the interface is not obvious, while the Ni and Mn elements strongly diffuse into the WC particle, which has a positive effect on the metallurgical bonding of the brazed joint.

Penetration Estimation of GTAW with C-Type Filler by Net Heat Input Ratio

Abstract: This study proposes a novel method to estimate the weld penetration in gas tungsten arc welding (GTAW) with filler metal. So far, there is no standard parameter available to accurately estimate penetration in GTAW with filler metal. Until now, the penetration could be estimated by heat input only in GTAW with and without filler metal. But in this study, it was revealed that the conventional heat input could not accurately estimate the penetration in GTAW with filler metal. Therefore, the new concept of net heat input ratio (NHIR), which is a ratio of net heat input to the bead cross-sectional area, was developed to accurately estimate the penetration in GTAW with filler metal. Using a C-type filler metal during GTAW, the NHIR was calculated for various welding conditions. The results showed that the NHIR was proportional to the welding current and voltage and inversely proportional to the welding speed and filler feed speed. Even though the NHIR was the same, the penetration increased as the welding current became higher. Four linear equations between NHIR and penetration were obtained from the experimental results for four levels of welding currents. By applying the concept of NHIR, the penetration could be estimated for any welding current.

Comparison of fatigue performance of TC4 titanium alloy welded by electron beam welding and laser welding with filler wire

Abstract: This research compared high-cycle fatigue (HCF) performances of joints of Ti–6Al–4V titanium (TC4) alloy with the thickness of 30 mm welded by vacuum electron beam welding (EBW) and laser welding with filler wire (LWFW) (hereinafter referred to as EBW and LWFW joints). Under test conditions, the fatigue strength of the LWFW joint is only 65% that of the EBW joint. Based on analysis, the main reason is that a larger microhardness gradient is present in the LWFW joint. The average microhardness of the weld metal (WM) of the LWFW joint is 41 HV lower than that of base metal (BM). A lot of punctate β phases in the WM of the LWFW joint may be an important reason for its softening. The research results provide data supports for the application of the EBW and LWFW of Ti alloy in the field of aviation manufacturing.

Effect of single alloying element (Ti, Nb, V, Cu) on microstructure and mechanical properties of dissimilar TiAl/Ni-based superalloy laser joints

Abstract: Dissimilar welding of TiAl-based alloy and Ni-based superalloy with different single alloying element (Ti, Nb, V, Cu) was performed by laser. Detailed effects of alloying element on microstructural characterization and mechanical properties of the joints were investigated. The results showed that laser welding of TiAl/Ni-based superalloy was not achieved by using Ti filler metal. The large number of Ni0.35Al0.30Ti0.35 brittle phases in the joint was the main factor of affecting the weldability of joint. Laser welding was not achieved a better connection by using Nb filler metal, and macrocracks existed in the weld, which mainly attributed to the formation of AlNbNi, AlNbNi2 and Cr2Nb intermetallics. The dissimilar metals was successfully welded by using V filler metal, and (V,Cr) solid solution and (V,Cr)/AlNi2Ti eutectic phase were formed in the weld zone. The average tensile strength of the joint was 140 MPa and the joint fracture occurred on Ni-based superalloy side, owing to the fine (V,Cr)/AlNi2Ti eutectic phase. The dissimilar metals was successfully welded by using Cu filler metal, and Cu solid solution and Al(Ni,Cu)2Ti/Cr eutectic phase were formed in the weld zone. The average tensile strength of the joint was 155 MPa and the joint fracture occurred on TiAl alloy side where more AlCuTi and AlCu2Ti formation has.

Effect of single alloying element (Ti, Nb, V, Cu) on microstructure and mechanical properties of dissimilar TiAl/Ni-based superalloy laser joints

Abstract: Dissimilar welding of TiAl-based alloy and Ni-based superalloy with different single alloying element (Ti, Nb, V, Cu) was performed by laser. Detailed effects of alloying element on microstructural characterization and mechanical properties of the joints were investigated. The results showed that laser welding of TiAl/Ni-based superalloy was not achieved by using Ti filler metal. The large number of Ni0.35Al0.30Ti0.35 brittle phases in the joint was the main factor of affecting the weldability of joint. Laser welding was not achieved a better connection by using Nb filler metal, and macrocracks existed in the weld, which mainly attributed to the formation of AlNbNi, AlNbNi2 and Cr2Nb intermetallics. The dissimilar metals was successfully welded by using V filler metal, and (V,Cr) solid solution and (V,Cr)/AlNi2Ti eutectic phase were formed in the weld zone. The average tensile strength of the joint was 140 MPa and the joint fracture occurred on Ni-based superalloy side, owing to the fine (V,Cr)/AlNi2Ti eutectic phase. The dissimilar metals was successfully welded by using Cu filler metal, and Cu solid solution and Al(Ni,Cu)2Ti/Cr eutectic phase were formed in the weld zone. The average tensile strength of the joint was 155 MPa and the joint fracture occurred on TiAl alloy side where more AlCuTi and AlCu2Ti formation has.

Experimental and theoretical study on air reaction wetting and brazing of Si3N4 ceramic by Ag-CuO filler metal: Performance and interfacial behavior

Abstract: Reactive air brazing of Si3N4 ceramic was successfully achieved by using Ag-CuO filler metal. The effects of CuO content on the wettability of Ag-CuO/Si3N4 system and the shear strength of Si3N4/Si3N4 joint were investigated, and meanwhile the interfacial behavior was analyzed and discussed. Moreover, the work of adhesion, interfacial energy, and electronic properties of Ag/Si3N4, Ag/CuO and Ag/SiO2 interfaces were evaluated by first-principles calculations. The Ag-CuO/Si3N4 system transforms from no-wetting into wetting due to the oxidation of Si3N4 substrate and the formation of SiO2 layer on the substrate surface. The maximum average joint shear strength of over 50 MPa is obtained as the CuO content is 8 at.%. Compared with the Ag(111)/Si3N4(0001) interface, the Ag(110)/CuO(001) and Ag(110)/SiO2(001) interfaces show stronger interfacial bonding due to the formation of Ag-O ionic bond, indicating that the addition of CuO and the formation of SiO2 contribute to the enhancement of interfacial bonding.

Effect of the thermal field on the microstructure of dissimilar welded joints between TWIP steel and 2205 duplex stainless steel

Abstract: This study reported a theoretical-experimental analysis of dissimilar metals duplex stainless steel (DSS) grade 2205 and twinning induced plasticity (TWIP) steel joined. Welded joints were performed in autogenous mode and using filler metal (ER2209) by the pulsed gas tungsten arc welding (GTAW-P) process. Critical weld regions were characterized metallographically using LOM and SEM. Microstructural changes such as the morphology and contents of ferritic and austenitic phases were correlated to the temperature ranges estimated numerically by a finite element (FE) model, which considered the variation of the percentage dilution in the fusion zone (FZ). The average variation between experimental and numerical results was up to 6.75%. SEM chemical analysis and line scanning analysis corroborated the diffusion of Al, Mn, Cr and Ni in the FZ of the autogenous joint. Small concentration gradients promoted a homogenous chemical composition of the ferritic and austenitic phases in the filler metal joint. The FZ exhibited an austenitic phase coarsening due to the elevated temperatures (1506°C–1803 °C, DSS 2205 side). Wetting problems were observed in both weldments producing prominent interfaces between the welded metal (WM) and the heat-affected zone (HAZ). Other weld defects such as underfilling, undercuts and lack of fusion were also detected. When a high TWIP steel volume was melted (filler metal joint), WM hardness increased compared to the autogenous joint. The hardness increment (2–5% in the DSS 2205) combined with the lack of fusion brought about the failure of the filler metal joint during the bend test.

Characteristics of laser-offset-TIG hybrid welding of AZ31Mg alloy with 6061Al alloy via Zn filler

Abstract: • This work proposed a laser-offset-TIG hybrid welding method to join Mg-Al dissimilar metals, the joint strength is 1.3 times higher than that with normal laser-TIG hybrid welding. • The laser-offset-TIG hybrid heat source can not only promote the wettability of filler metal , but also inhibit the formation of brittle Mg-Zn IMCs . • The attraction effect of the laser to arc is conducive to reducing the heat input on Mg base metal. This work proposed a laser-offset-TIG hybrid welding method to join AZ31 Mg alloy to 6061 Al alloy with Zn filler in lap configuration. Through the lateral offset of laser and arc, the wettability of filler metal was improved, and the amount of intermetallic compounds (IMCs) was well controlled. The spread width of filler metal increases from 2.13 mm to 3.49 mm and the reaction depth decreases from 0.91 mm to 0.66 mm as the offset distance increases from 0 mm to 2 mm. The major phases formed in joint are Al solid solution, MgZn 2 IMCs, Zn solid solution and Mg 32 (Al,Zn) 49 ternary IMCs. At the appropriate offset distance of 2 mm, the coarse MgZn 2 grains in fusion zone are refined to (Al)+(Zn)+MgZn 2 eutectic, and the brittle Mg 32 (Al,Zn) 49 ternary IMCs in weld corner are eliminated. The maximum joint strength is 1190 N/cm, which is 1.3 times higher than that with normal laser-TIG hybrid welding.

Comparative study of laser swelding-brazing of aluminum alloy to galvanized steel butted joints using five different filler wires

Abstract: The purpose of this paper is to provide the gist for the selection of filler wire during the laser welding-brazing of Al to steel. A comprehensive comparison of laser welding-brazing 5052 aluminum alloy to unbeveled galvanized steel using pure Al, AlSi5, AlMg5, AlCu6, and ZnAl2 filler wires were conducted with varied laser beam offset. The comparison was carried out in terms of weld formation, interfacial microstructures, and mechanical properties. The results show that the fluidity of liquid filler is Pure Al AlMg5 > AlCu6 > ZnAl2 > pure Al. The fracture of the joints all occurred at the brittle intermetallic layers when five different filler wires were used.

Comparative study of laser swelding-brazing of aluminum alloy to galvanized steel butted joints using five different filler wires

Abstract: The purpose of this paper is to provide the gist for the selection of filler wire during the laser welding-brazing of Al to steel. A comprehensive comparison of laser welding-brazing 5052 aluminum alloy to unbeveled galvanized steel using pure Al, AlSi5, AlMg5, AlCu6, and ZnAl2 filler wires were conducted with varied laser beam offset. The comparison was carried out in terms of weld formation, interfacial microstructures, and mechanical properties. The results show that the fluidity of liquid filler is Pure Al < AlSi5 < AlMg5 < AlCu6 < ZnAl2. Too small or too large fluidity will lead to poor weld formation. The interfacial intermetallic compound consisted of layered Fe2Al5 and scattered FeAl3 when pure Al, AlMg5, and AlCu6 filler wires were used. When pure Al filler wire was used, cracks were most likely to occur in the reaction layer. The other four filler wire all improved the crack resistance. The thickness of the reaction layer significantly decreased when AlSi5 filler wire was used. Si element was found as a solid solution in the reaction layer to form Fe2(Al, Si)5 and Fe(Al, Si)3. A large amount of FeZn10 was mixed between Fe2(Al, Zn)5 when using ZnAl2 filler wire. The order of maximum tensile strength of the joints using different filler wires was AlSi5 > AlMg5 > AlCu6 > ZnAl2 > pure Al. The fracture of the joints all occurred at the brittle intermetallic layers when five different filler wires were used.

Ultra-Narrow Gap Fiber Laser Conduction Welding Technology for 304 Stainless Steel Thick Plates and the Mechanical Properties of Welding Joints

Abstract: The application of thick metal plates is increasing, and the welding problem is becoming more and more prominent. Narrow gap laser welding is one of the important methods, and it is also a research hotspot. The stainless steel thick plates were welded using the ultra-narrow gap fiber laser conduction welding with filler wire. Results show that the ranges of technological parameters for the achievement of the weld seam with no defects are smaller when the gap width is comparatively larger. Using the optimized technological parameters, the butt welding with no defects on the 3 mm gap between two 304 stainless steel plates with 60 mm thickness was achieved through the filling 20 times. This welding method of 304 metal with large thickness is rare in the literature. The tensile strength of the welding joint can be up to 87% of that of the base metal, and the micro-hardness and yield strength of the joint are comparable with those of the base metal.