Steel Filler Research Articles

Microstructural Analysis on Ballistic Tested Armour Steel Joints Fabricated Using Low Hydrogen Ferritic Consumables for Capping Pass

Post impact microstructural characteristics of 7.62 armour pearcing incendiary bullet was studied on AISI 4340 multilayerd welded joints. The potential application of AISI 4340 steel is found in the construction of combat vehicles using welding process. The welded joints are expected to offer better ballistic resistance like unwelded parent metals in combat vehicles. The traditionally used austenitic stainless steel welding consumables and the transformation effects of the welding process result in inferior ballistic performance of AISI 4340 steel welded joints. Published information revealed that a few attempts were made to successfully resist the bullets at multi layered weld metals by depositing a hard-facing interlayer between traditionally used austenitic stainless steel filler metals and a austenitic stainless steel buttering layer in between the parent metal and the hard – facing interlayer. This paper reports the pre-impact and post-impact microstructural characteristics of multi layered sandwiched joints made of a austenitic stainless steel root, a chromium carbide hard – facing middle layer and a low hydrogen ferritic capping front layer. The effect of the low hydrogen ferritic front layer on the ballistic performance after impact is studied in detail.

Dissimilar Welding of Maraging Steel (250) and 13-8 Mo Stainless Steel by GTCAW, LBW and EBW Processes

The frequently used aerospace materials, i.e., ultra-high-strength maraging steel (250) and corrosion-resistant 13-8 Mo stainless steel in the solution-annealed and cold-worked condition, have been joined by three fusion welding processes, namely interpulse TIG welding, and high energy density fusion processes like electron beam welding (EBW) and laser beam welding (LBW). The interpulse TIG welding process was carried out by using W2 grade maraging steel filler wire. The dissimilar joints were welded by EBW and LBW processes without any filler wire. All the dissimilar welded joints were characterized by microstructural observations and validated by mechanical properties in the as-welded as well as precipitation-hardened conditions after welding. The weld microstructures and microhardness profiles were correlated to the tensile strength of weld. Electron beam welded joint with precipitation hardening after welding, i.e., soaking at 510 °C and subsequent air cooling, demonstrated the superior mechanical properties among all the welds.

Filler Metal Mixing Behaviour of 10 mm Thick Stainless Steel Butt-Joint Welds Produced with Laser-Arc Hybrid and Laser Cold-Wire Processes

In thick section laser welding, filler metal addition is usually required to improve joint fit-up tolerances or to control the chemical composition of the weld metal. With deep and narrow welds produced using an over-alloyed filler metal, it may be challenging to ensure that the filler metal and its elements are homogeneously mixed and evenly distributed throughout the fusion zone. Inhomogeneous filler metal mixing can cause unfavourable changes to weld metal chemistry and microstructure. Filler metal mixing behaviour in laser-arc hybrid and laser cold-wire welding is studied in this work. Welding tests were conducted on 10 mm thick butt-welded joints of AISI 316L austenitic stainless steel. An overmatching type 2205 duplex stainless steel filler wire was used to obtain a composition contrast between the base metal and filler metal. Energy dispersive spectroscopy (EDS) with chromium as the trace element was used for element mapping and stepwise characterization of the weld cross-section samples. Optical metallography was used to observe possible inhomogeneous filler metal mixing behaviour like local acute changes in macro- and microstructural features. The results showed a clear difference in filler metal mixing between the weld surface part (upper half) of the weld and the weld root part (lower half) in 10 mm thick welded cross-sections for closed root gap of I-groove welds or when the gap was only 0.4 mm. In narrow I-groove preparations, inhomogeneous mixing phenomena were more pronounced in laser cold-wire welds than in laser-arc hybrid welds. In both welding processes, a combination of trailing wire feeding and the use of a wider groove enabled filler metal to be introduced deeper into the bottom of the groove and improved mixing in the root portion of the welds.

Stability evaluation of laser-MAG hybrid welding process

This paper describes the laser-MAG hybrid welding of high-strength steel (HSS) formulated with 1.2 mm diameter austenitic stainless steel (ASS) filler wire. A high-speed camera and Hannover analyzers were used to obtain real-time images of droplets and electrical signals during the hybrid welding process. Image processing and mathematical statistics were performed to study how the ratio of laser power to arc power affected the weld morphology, droplet transfer characteristics, instantaneous current probability density. The welding stability was evaluated by using the variation rate of weld width as the main reference. This study provides the fundamentals necessary to select reasonable parameters to obtain better weld stability during the laser-MAG hybrid welding process. The results of this study show that both the laser power and arc power strongly influence both the penetration depth and the width of the weld during the laser-MAG hybrid welding process, respectively. The droplet transfer mode and the ratio of laser energy to arc energy are strongly affected by the distance between the laser and the arc in the laser-MAG hybrid welding process. The droplets have a negligible effect on the keyholes when the distance between the laser and arc is in the range of 2.5–3.5 mm. The welding current is 160 A, which is the critical current of short-circuiting transfer to globular transfer. The critical transition current of globular transfer and projected transfer was shown to occur at a welding current of 180 A. When the welding current is 206 A, the critical transition current of projected transfer and spray transfer is observed. When the welding current is 206–240 A, the fluctuation of the width of weld beam is not significant. When the droplet transfer mode is projected transfer, the welding stability is the best.

A Review of Application and Use of Dissimilar Metal Welding

Objective: This work aims to give a complete viewpoint of the nitty-gritty experiences with examinations and examination concerning novel weld joints. Methods/ Statistical Analysis: This ongoing exploration gives a whole review of metallurgical properties of various weld joints, push/strain of the weld and arrangement of joint disillusionment of unique joints. Findings: It has been evaluated that most of the disillusionment has been connected with austenitic treated steel filler metal joints. It has been found that the joint structure – groove point – and weld quality interrelationship is considered by various people to be an immense variable. Application/Improvements: The sort of weld metal is of absolute centrality from the scattering and warm limitation perspectives. Keywords: Dissimilar Metals, Steel, Welding

Hybrid laser arc welding of dissimilar TWIP and DP high strength steel weld

High manganese TWIP steels have a remarkable potential to produce impact resistant car body parts in the automotive industry. Hybrid laser arc welding (HLAW), i.e. simultaneous action of an arc and laser source, can be regarded as the most promising joining technique for such components due to, among other factors, the possibility to use filler metals to avoid improper microstructures and Mn chemical segregations in dissimilar welds of TWIP with other steel grades. In this regard, this work studies the influence of the main welding settings during HLAW of 1.4 mm thick TWIP and Dual Phase (DP) steel sheets used in the automotive industry, which were joined with the use of an austenitic steel filler. Quality of TWIP-DP welds was investigated based on welding parameters, tensile and hardness properties, and microstructures.TWIP and DP steel sheets can be properly joined with a linear heat input in the 50–75 kJ/m range. Welded samples exhibit an average tensile strength and elongation at fracture roughly of 650 MPa and 13%, respectively. These values are similar to those of DP steel, but significantly lower than TWIP steel. The tensile welded samples failed within the heat affected zone of DP steel, being weldments and TWIP steel more resistant. This work confirms that HLAW can be considered a promising solution to join vehicle components made of TWIP and DP sheets when fillers are needed.

Influences of Groove Angles and Filler Metals on 304L Stainless Steel to AISI 1040 Carbon Steel Dissimilar Joint by Gas Tungsten Arc Welding

Dissimilar joint commonly applied on pressure vessel application in power plan field as joining between the tank and the stanchion of pressure vessel. This paper presents the investigations carried out to study the influence of groove angles and filler metals on 304L Stainless Steel to AISI 1040 Carbon Steel dissimilar joints. Gas Tungsten Arc Welding with 120 A of current was used on this research, joined the two different metals. The 30°, 45°, and 60° were used in this welding as parameters of V-groove angles. ER 308L-16 filler metal of stainless steel and ER 70S-6 filler metal of carbon steel were used as filler metals. Tensile test was conducted to obtain tensile strength of joint and to analysis of the effect of the welding parameters to the mechanical properties. The highest tensile strength was obtained from the 60° groove angle using ER 308L-16 filler metal of 614.54 MPa. In the other hand, 45° groove angle using ER 70S-6 filler metal obtained the lowest tensile strength of 578.66 MPa. The joining process of dissimilar welding using ER 308L-16 filler metal, filler metal for stainless steel, has obtained the highest tensile strength with wider groove angle as well.

Effect Of Welding Speed On Weld Bead Geometry And Percentage Dilution In Gas Metal Arc Welding Of SS409L

Abstract Welding process parameters are the controlling factor for percentage dilution and weld bead geometry (bead width, bead height and penetration). Percentage dilution and weld bead geometry are very important factors to determine the quality of the joints. Present work aims to investigate the effect of welding speed (300, 400 and 500 mm/minute) on percentage dilution and weld bead geometry. Gas metal arc welding of ferritic stainless steel SS409L with austenitic stainless steel filler wire ER304L using pure argon gas has been done. The study of percentage dilution and weld bead geometry has been carried out. It has been found out that with increasing welding speed, bead width, bead height and penetration decreases but percentage dilution first increases with the welding speed parameter and then decreases with further increase in these values.

Fiber laser-MAG hybrid welding of DP/AISI 316 and TWIP/AISI 316 dissimilar weld

In this paper, TWinning-Induced Plasticity (TWIP), Dual Phase (DP) and austenitic stainless (AISI 316) steels were joined together by hybrid laser/arc welding with an austenitic steel filler. Microstructural and mechanical characterization of welded joints was carried out by optical microscopy, microhardness, tensile and bend tests. The heat affected zone (HAZ) at the TWIP side was fully austenitic and exhibited a grain coarsening; at the DP side, new martensite formed close to the fusion zone and other phase transformations occurred moving toward the base metal; at the AISI 316 side, stringers of untreated ferrite δ inside the austenitic matrix was observed. All the tensile welded specimens broke within austenitic stainless steel. TWIP/AISI 316 welds exhibited a greater tensile strength than DP/AISI 316 ones. The bending tests confirmed the ductility of both sorts of joints.

The influences of different filler metals on the microstructure of Invar Fe-36Ni alloy multi-layer multi-pass MIG welding

The Invar Fe-36Ni alloy plates are welded by multi-layer multi-pass MIG welding with two kinds of filler metals in this paper. The microstructure of the joints is studied using scanning electron microscopy, x ray diffraction, and energy dispersive x-ray spectroscopy. And the morphology and microstructure of the joints with two different filler metals are compared. Moreover, the element distributions at different location are discussed. The results indicate that there are no pores or crack defects on the surface of the weld seam. The sizes of the incomplete fusion, which occurred in the interior of weld seam, using stainless steel filler metal are much larger than that of using Invar M93 filler metal. The distributions of elements in the interlayer are homogeneous using two filler metals. However, the element distributions, which are perpendicular to the fusion line, are not uniform using steel filler metal. The experimental results illustrate that the M93 Invar welding filler is better than stainless steel filler metal for multi-pass welding process of Invar Fe-36Ni alloy.

Prediction of grain orientation in dissimilar metal weld using ultrasonic response of numerical simulation from deliberated scatterers

Ultrasonic nondestructive testing plays an important role in structural integrity monitoring of dissimilar metal weld (DMW) structures in pressure vessels and piping of nuclear power plants. Inspection of DMW components is too complicated due to its anisotropic behavior to ultrasonic beam propagation. Many researchers are working rigorously to model the grain orientation and ultrasonic beam skewing in DMW structures but still not completely resolved yet. This paper is intended to estimate the grain orientation with the help of numerical simulation for a given asymmetric DMW component with specified scatterers. The DMW is fabricated from austenite stainless steel and carbon steel base metals with austenite stainless steel filler metal using Gas Tungsten-Arc Welding. To study this research a finite element method (FEM) based numerical simulation has been used to exactly evaluate the grain structure. This model mainly depends on the elasticity matrix which is a function of the grain orientation and attenuation of ultrasonic energy of the weld. Iterative measurement of grain orientation using macrograph of the etched weldment with 5 × 5mm mesh size was carried out then the attenuated elasticity matrix was fed into the FEM COMSOL software model as input parameter. Result obtained from numerical simulation (time of flight and amplitude) are validated with the experimental result and good agreement (above 0.8 correlation coefficient) have been observed at higher iterations. This macro-graphic information based numerical model shows the potential to predict the grain orientation of DMW.

Microstructural Characterization and Mechanical Properties of TIG-Welded API 5L X60 HSLA Steel and AISI 310S Stainless Steel Dissimilar Joints

Dissimilar joining of API 5L X60 ferritic HSLA steel and AISI 310S austenitic stainless steel was conducted by tungsten inert gas (TIG) welding process using ERNiCr-3, ER310, ER2209, and ER309L filler metals. Microstructural characteristics and mechanical properties of the weldments were studied using optical and scanning electron microscopy, ferritometry, microhardness, tensile, and impact tests. The microstructure investigations revealed macro-segregation occurrence and formation of Type II boundaries at the interface of welds with API 5L X60 steel. In tension tests, the joints prepared by ER2209 filler metal showed the maximum yield and ultimate tensile strength values, and the failures were always obtained at the side of API 5L X60. The results of Charpy impact tests indicated that the maximum fracture energy is related to the weld made by ER2209 filler metal. At last, it was concluded that for the dissimilar welding between API 5L X60 and AISI 310S, the weld metal prepared by ER2209 duplex stainless steel filler metal offers the optimum properties at room temperature.

Effects of shielding gas composition on the welding stability, microstructure and mechanical properties in laser-arc hybrid welding of high nitrogen steel

This paper deals with laser-arc hybrid welding of high nitrogen stainless steel (HNS) with 1.2 mm diameter of austenitic stainless steel (ASS) filler wire. The welding was carried out with different shielding gas mixtures like 100%Ar, 95%Ar + 5%N2, 90%Ar + 10%N2, 94%Ar + 5%N2 + 1%O2 and 89%Ar + 10%N2 + 1%O2. The effects of shielding gas composition on the welding stability, microstructure and mechanical properties were analyzed. The results show that the weld seam forming and welding stability are improved when 1%O2 is added to the mixture of Ar + N2, and the nitrogen content in the weld increases significantly. The pore ratio is the lowest in 90%Ar + 10%N2 shielded weld, when 1%O2 is added to 90%Ar + 10%N2, the pore ratio increases slightly. The ferrite percentage is the lowest in 89%Ar + 10%N2 + 1%O2 shielded weld. The 89%Ar + 10%N2 + 1%O2 shielded welded joints feature better mechanical properties.

Microstructure and mechanical properties of similar and dissimilar metal gas tungsten constricted arc welds: Maraging steel to 13-8 Mo stainless steel

Abstract Maraging steel (250) and 13-8 Mo stainless steel plates were joined by gas tungsten constricted arc welding (GTCAW) process in similar and dissimilar metal combinations using 13-8 Mo stainless steel filler wire. The similar and dissimilar metal welds made in solutionized condition were subjected to standard post weld hardening treatments direct ageing at 485 °C, soaking for 3½ hours followed by air cooling (ageing treatment of maraging steel) and direct ageing at 510 °C, soaking for 4 h followed by air cooling (ageing treatment of 13-8 Mo stainless steel). The joint characterization studies include microstructure examination, microhardness survey across the weldments and transverse weld tensile test. Similar and dissimilar metal weldments responded to both the post weld ageing treatment. After post weld aging, increase in yield strength, UTS and slight reduction in % elongation of similar and dissimilar metal were observed. The observed tensile properties were correlated with microstructure and hardness distribution across the welds.

Investigation on the Effect of Activating Flux on Tungsten Inert Gas Welding of Austenitic Stainless Steel Using AC Polarity

Tungsten Inert Gas (TIG) welding is a popular joining process due to its inherent capability in producing superior quality welding in a wide range of materials. However, lower productivity of it paves the way for introduction of a number of variants of TIG welding, including Flux Bounded TIG (FB-TIG) welding and Activated TIG (A-TIG) welding. In this paper, variations of weld morphology and characteristics with heat input in AC A-TIG welding of both bead-on-plate and butt joining of 6mm thick 316L stainless steel plates using TiO 2 , Cr 2 O 3 and Fe 2 O 3 as activating flux and a stainless steel filler material are investigated. Results are also compared with that obtained in conventional TIG welding. Variations of various weld characteristics viz. depth of penetration, width of weld bead, reinforcement, Reinforcement Form Factor (RFF), and Penetration Shape Factor (PSF) against change in heat input are analyzed and compared. It is observed that TiO2 and Fe 2 O 3 fluxes effectively enhance the penetration due to increase in fluidity and wettability of molten metal and, at the same time, reduce the width of weld bead; whereas, Cr 2 O 3 flux gives inferior results as it reduces penetration instead of increasing it as compared to conventional TIG welding.

Construction of a short circuit frequency map to define GMAW-S parameters during WPSs development

Se construyó un mapa de frecuencias para GMAW-S usando un aporte clase AWS ER70S-6 y gas de protección 75%Ar-25%CO2. Este tipo de mapa es una herramienta para seleccionar corrientes y voltajes de soldeo con proceso GMAW-S con mayor estabilidad. El mapa se construyó analizando señales de voltaje y amperaje registradas durante la aplicación de soldaduras a 5000 muestras por segundo. Se definieron regiones de operación sobre los mapas basados en resultados de inspección visual de soldaduras sobre platina y ubicando los límites de inestabilidad. Se analizaron dos ejemplos de parámetros de calificación de soldaduras usados industrialmente (corriente y voltaje) dibujando los límites establecidos por el código AWS D1.1:2015 para estas variables esenciales (±7% en voltaje y ±10% en amperaje del PQR) en el mapa de frecuencias. Se mostró como estos límites pueden contener regiones de baja estabilidad asociada al “stubbing” contra el metal base y al no reinicio del arco.

Stress Corrosion Cracking Behaviour of Dissimilar Welding of AISI 310S Austenitic Stainless Steel to 2304 Duplex Stainless Steel

The influence of the weld metal chemistry on the stress corrosion cracking (SCC) susceptibility of dissimilar weldments between 310S austenitic stainless steel and 2304 duplex steels was investigated by constant load tests and microstructural examination. Two filler metals (E309L and E2209) were used to produce fusion zones of different chemical compositions. The SCC results showed that the heat affected zone (HAZ) on the 2304 base metal side of the weldments was the most susceptible region to SCC for both filler metals tested. The SCC results also showed that the weldments with 2209 duplex steel filler metal presented the best SCC resistance when compared to the weldments with E309L filler metal. The lower SCC resistance of the dissimilar joint with 309L austenitic steel filler metal may be attributed to (1) the presence of brittle chi/sigma phase in the HAZ on the 2304 base metal, which produced SC cracks in this region and (2) the presence of a semi-continuous delta-ferrite network in the fusion zone which favored the nucleation and propagation of SC cracks from the fusion zone to HAZ of the 2304 stainless steel. Thus, the SC cracks from the fusion zone associated with the SC cracks of 2304 HAZ decreased considerably the time-of-fracture on this region, where the fracture occurred. Although the dissimilar weldment with E2209 filler metal also presented SC cracks in the HAZ on the 2304 side, it did not present the delta ferrite network in the fusion zone due to its chemical composition. Fractography analyses showed that the mixed fracture mode was predominant for both filler metals used.

Effective Dispersion of Carbon Nanotube in Epoxy Grout for Structural Rehabilitation

The industry nowadays is incorporating the composite repair system for repairing pipelines rather than the conventional steel repair. The mechanism of this repair method usually consists of three components which are the composite wrapping, infill material and the adhesive. However, there has been very little research on the function of the infill in the repair mechanism. This work is concerning the enhancement of the performance or the strength properties of the infill material in pipeline repair by reinforcing the putty with carbon nanotubes (CNT). The enhancement of the performance of the infill has been carried out by dispersing the CNT into epoxy resin with a three roll mill. In the mechanical properties testing, it is found that the CNT is an effective material to improve the tensile strength of the epoxy grout. However, the CNT-modified samples in the compressive property test show a contrast to the tensile test. All the CNT-modified samples exhibit a lower compressive strength than the control sample and the milled down sample. In conclusion, CNT shows the potential to be a very good material to enhance the mechanical properties of epoxy grout, however, with this specific brand of epoxy grout that contains steel filler in the resin, the CNT only improve the tensile properties but the compressive properties of the epoxy grout has been compromised as compared to the control sample.

Development of copper coating technology on high strength low alloy steel filler wire for aerospace applications

0.3C-CrMoV(ESR) grade steel is considered as a potential candidate for realizing solid booster cases in aerospace applications due to its high strength coupled with toughness. To obtain the maximum weld efficiency, these steels are welded using filler wires of the same chemical composition. However, due to inherent corrosive nature, bare filler wires could not be stored for long time. To overcome this problem, a suitable coating technology using copper as coating material has been developed which provides uniform, adherent and thin coating on the wire and do not impair the required mechanical properties of weldment. In order to alleviate the gas pick-up issues associated with electro-plating technique and considering the product configuration, immersion coating technique was adopted. Process optimization to obtain a uniform and adherent coating on wire spools was carried out. Wires were also analysed for coating thickness, adhesion and gases (O, H, N). Coating has been observed to be adherent and gas content were found within the aerospace specification. Further, weldment realized using coated filler wire shows similar quality of weldments and properties as obtained through uncoated filler wire, confirming this process and coating can be adaptable for storage of filler wire.

Finite Element Simulation of Temperature Distribution, Distortion and Residual Stresses of Dissimilar Welded Joints

In our paper, Goldak’s single-ellipsoid model which gives the heat flux distribution for a moving heat source is presented. ANSYS APDL Code was written for carrying out thermal and structural simulation of the welding of a butt joint with heat inputs incorporated into each element. The welded structure is dissimilar butt joint, made with combination of IS2062 Steel and Inconel 718 using steel filler metals. The distribution of temperatures both with respect to spatial coordinates and time for the dissimilar weld plate structures during welding was simulated. The fusion and heat affected zones were identified. The consequences of the having distributed heat source, different inputs of heat energy and speeds of welding on changes in temperature were investigated. The results of thermal analysis have been picked up by structural analysis to determine the possible plate distortions. The patterns of Residual stresses have also been simulated.