Steel Dissimilar Weld Research Articles

The influence of laser welding configuration on the properties of dissimilar stainless steel welds

Laser beam welding of dissimilar ferritic/martensitic stainless steels was performed in constrained butt joint configuration with the objective of identifying the influence of the melting ratio between the two base metals on the ultimate shear strength of the welds. Based on a full factorial design, experiments demonstrated that varying the incidence angle up to 45° and offsetting the focal position with respect to the materials’ interface within the limits imposed by the laser spot diameter are a reliable method to control the melting ratio and maintaining the expected resistance length at the material interface. The weld configuration parameters were correlated by means of the analysis of variance (ANOVA) method with shear resistance length and the melting ratio: the incidence of surface cracks can be significantly reduced increasing the ferritic steel area, involved in the formation of seam, over 60 % of the whole melt zone. Push-out tests performed on the specimens revealed that such a configuration has beneficial aspects on the ultimate shear strength of the seam meaning that the prevailing effect is the decreased brittleness of the weld by decreasing its carbon content under 0.5 % in weight.

Stress Corrosion Cracking Behavior in the Transition Region of Alloy 182/Low-Alloy Reactor Pressure Vessel Steel Dissimilar Metal Weld Joints in Light Water Reactor Environments

The stress corrosion cracking (SCC) behavior perpendicular to the fusion line in the transition region between the alloy 182 nickel-base weld metal and the adjacent low-alloy reactor pressure vessel (RPV) steel of simulated dissimilar metal weld joints was investigated under boiling-water reactor normal-water chemistry conditions at different stress intensities and chloride concentrations. A special emphasis was placed on the question whether a fast growing interdendritic SCC crack in the highly susceptible alloy 182 weld metal can easily cross the fusion line and significantly propagate into the adjacent low-alloy RPV steel. Cessation of interdendritic stress corrosion crack growth was observed in high-purity or sulfate-containing oxygenated water under periodical partial unloading or constant loading conditions with stress intensity factors below 60 MPa·m1/2 for those parts of the crack front that reached the fusion line. In chloride containing water, on the other hand, the interdendritic stress corrosi...

A study on the control of melting ratio to increase mechanical properties of laser welded joints between AISI 440C and AISI 430F

Abstract Laser beam welding of dissimilar AISI 440C and AISI 430F stainless steels was investigated in a circular constrained configuration. The beam incidence angle and the offset of the focusing position respect to the contact point between the two materials were used as main control parameters to vary the melting ratio inside the seam. The objective of the study is twofold: to avoid surface microcracks related to the high percentage of carbon of the martensitic steel and to enhance the shear strength of the weld by making it less brittle. To reach this scope the effects of incidence angle and offset on weld bead geometry and melting ratio were studied by means of metallographic analyses, microstructure and microhardness characterization. As last step, the weld mechanical strength was tested by tensile-shear stress test on the whole seam. Experiments demonstrated that varying incidence angle and offsetting the focal position is a reliable method to modify the melting ratio and maintaining the expected resistance length at the material interface, as well. It was found that increasing the percentage of ferritic steel into the joint has beneficial effects on the weld quality and on the shear resistance. The critical carbon content determining the mechanical properties in the fusion zone can be calculated by taking into account the melting ratio.

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF THE WELDING JOINT OF A NEW CORROSION- RESISTING NICKEL-BASED ALLOY AND 304 AUSTENITIC STAINLESS STEEL

With the fast development of industry, a serious global problem, pollution, becomes more apparent. A large number of wastewater is discharged, causing the environment pollution. Supercritical water oxidation(SCWO) becomes the most effective method to treat the wastewater within recent years, but the material used in the equipment plays a key role in restricting the application of the SCWO process. Currently, during the SCWO wastewater treatment process, 304 austenitic stainless steel, alloy 625, P91 and P92 steels are the mainly preheater and reactor materials. In order to reduce the serious corrosion and improve economic efficiency of the materials for this process, a new corrosion resistant Ni-based alloy(called X-2# alloy) has been developed with an aim of replacing the previous ones. In particular, it is highly important to the related behavior of this new alloy welding with the original SCWO. Therefore, the microstructure and mechanical properties of the welding joint of the new alloy and304 austenitic stainless steel with manual argon arc welding were investigated. The microstructure and fracture morphologies of the welding joint were analyzed through OM, SEM and EDS, and the detailed analysis of the micro- hardness, tensile strength and other mechanical properties were performed. The results demonstrated that the parent material with the typical 40~65 mm grains size is helpful for dissimilar steel welding, and the microstructurein fusion zone of X-2# side does not show welding defects. However, some ferrites are further formed near the fusion zone of 304 stainless steel sides. There are Cr-rich and Ni-poor distributions in the ferrites. The grain grows seriously in both the areas near the remelt zone and 304 stainless steel side of heat affected zones(HAZs), which affect heavily the performance of welding joint. In addition, the results also uncover that the Vickers-hardness is the minimum in the HAZ. At room temperature, the fracture location of the tensile tests of X-2#/304 is in the welding seam, whereas at 500 ℃ the corresponding position is in the 304 matrix. Due to the strengthening effects of Al, W and Mo elements, the high temperature mechanical properties of X-2# alloy have been found to be even better than those of the 304 austenitic stainless steel.

Review of Research Progress on Aluminum–Steel Dissimilar Welding

This paper presents a review of research progress on aluminum–steel dissimilar welding. Current issues and recent developments in improving the intermetallic compound layer of weld joint are critically assessed. Several welding factors that improve joint quality, such as welding method, weld and material preparations, as well as welding parameters, are also discussed. This study also examines recent developments in hybrid welding techniques and proposes a preheating method to enhance the weld joints of aluminum–steel dissimilar welding.

Selection of shielding gas for mechanized arc welding of dissimilar steels

Selection of shielding gas for mechanized arc welding of dissimilar steels

In-situ investigation of thermal aging effect on oxide formation in Ni-base alloy/low alloy steel dissimilar metal weld interfaces

The thermal aging effect on the formation of oxide films at the interfaces of nickel-base alloy/low alloy steel dissimilar metal welds has been analyzed by in-situ Raman spectroscopy. Experimental conditions were controlled so as to simulate a pressurized water reactor primary water condition, with in-situ spectra recorded at 300°C for 50h. The results indicate the formation of Cr2O3, Fe3O4, and FeCr2O3 in as-welded samples, whereas thermal aging is found to form NiCr2O4 and NiFe2O4. In this study, therefore, it is determined that the thermal aging creates a susceptibility to stress corrosion cracking that is not present in the as-welded sample.

A Study on the Effect of the Interpass Temperatures in Properties and Microstructures of the Alloy 625 Dissimilar Fusion Zone

The purpose of this study is to evaluate the effectiveness in the contribution of the interpass welding in the microstructures and properties of the dissimilar fusion zones produced with an alloy 625 and API 5L X65 steel pipes. Three multipass welded joints with v-groove, were made under the same welding parameters, therefore, changing only the interpass temperatures at: 150°C, 250°C and 450°C. The microstructural characterization was performed using the light microscopy and the scanning electron microscopy (SEM). The hardness test, charpy-V impact test and the transverse tensile test were conducted according to specific standards. The results have shown that all ruptures in the tensile tests occurred in the base metal. Both yield strengths and ultimate tensile strengths, have dropped to the 450°C interpass temperature. It was also observed a slight drop in the hardness with increasing interpass temperature. The Charpy-V impact test results showed no significant differences among the interpass temperatures. These said results indicated that the maximum interpass temperature for the alloy 625/X65 steel dissimilar welding is limited by the steel properties.

Study on microstructure and mechanical characteristics of low-carbon steel and ferritic stainless steel joints

In this work, examinations on the microstructure and mechanical properties of plain carbon steel and AISI 430 ferritic stainless steel dissimilar welds are carried out. Welding is conducted in both autogenous and using ER309L austenitic filler rod conditions through gas tungsten arc welding process. The results indicate that fully-ferritic and duplex ferritic–martensitic microstructures are formed for autogenous and filler-added welds, respectively. Carbide precipitation and formation of martensite at ferrite grain boundaries (intergranular martensite) as well as grain growth occur in the heat affected zone (HAZ) of AISI 430 steel. It is found that weld heat input can strongly affect grain growth phenomenon along with the amount and the composition of carbides and intergranular martensite. Acquired mechanical characteristics of weld in the case of using filler metal are significantly higher than those of autogenous one. Accordingly, ultimate tensile strength (UTS), hardness, and absorbed energy during tensile test of weld metal are increased from 662MPa to 910MPa, 140Hv to 385Hv, and 53.6Jm−3 to 79Jm−3, respectively by filler metal addition. From fracture surfaces, predominantly ductile fracture is observed in the specimen welded with filler metal while mainly cleavage fracture occurs in the autogenous weld metal.

In situ Raman spectroscopic analysis of surface oxide films on Ni-base alloy/low alloy steel dissimilar metal weld interfaces in high-temperature water

In situ Raman spectroscopy has been applied to analyze the surface oxide films formed on dissimilar metal weld (DMW) interfaces of nickel-base alloy/low alloy steel under hydrogenated high-temperature water condition. For the analysis of the oxide films under high temperature/pressure aqueous conditions, an in situ Raman spectroscopy system was developed by constructing a hydrothermal cell where the entire optics including the excitation laser and the Raman light collection system were located at the nearest position to the specimen by means of immersion optics. In situ Raman spectra of the DMW interfaces were collected in hydrogenated water condition at different temperatures up to 300°C. The measured in situ Raman spectra showed peaks of Cr2O3, NiCr2O4 and Fe3O4 at the DMW interface. It is considered that differences in the oxide chemistry originated from the chemical element distribution inside of the DMW interface region.

High temperature tensile test and creep rupture strength prediction of T92/Super304H dissimilar steel weld joints

After short term tensile test at 823–923 K, microstructure, fractography and fracture mechanism of the T92/Super304H dissimilar steel weld joints were studied. In the high temperature tensile process, the fracture location of all joints is in the T92 base metal; however, the fracture mechanism of these joints changes from a normal mode to a shear mode with the increase of the temperature. Moreover, an equation of the creep rupture strength related to the short term tensile strength of the joints was firstly derived in terms of the Goldenberg model. And then the creep rupture strength of the joints was obtained, = 42·7 MPa.

English

Aluminum-stainless steel dissimilar welding processes yield unwanted disadvantages in the weld joint due to the large difference between the aluminum-stainless steel sheets’ melting points and the nearly zero solid solubility between these two metals. Aluminum AA6061 and stainless steel SUS304 were lap-welded by using Metal Inert Gas (MIG) welding with aluminum filler ER5356 (Group 1) and stainless steel filler ER308LSi (Group 2). The effects of the welding voltage and type of filler metals used on the weld joints were studied. The welding voltage had a significant effect on the welding process, as higher voltage resulted in poorer appearance of the weld joint and led to defects for both groups, such as porosity and incomplete fusion. The microstructure for Group 1 joints shows enrichment of Si particles, which benefited the joint properties as it increased the strength of the metal. The stainless steel substrates that spread into the aluminum side are much greater in volume for Group 1 than for Group 2 joints. Meanwhile, the microstructure of Group 2 joints (using ER308LSi filler) consists of chromium carbide precipitation which yields a high hardness value, but a brittle structure. The hardness values of the welded seams in Group 1 and Group 2 range from 60 to 100 HV and 160 to 230 HV, respectively. The fracture in the tensile test yielded the highest tensile strength of 104.4 MPa with aluminum fillers. The tensile strength of Group 1 joints ranging from 47.8 to 104.4 MPa was collectively higher than Group 2 joints, between 20.24 to 61.76 MPa. Based on the investigation throughout this study, it can be concluded that the welding voltage of 18 V and aluminum filler ER5356 is the optimum filler in joining the dissimilar metals aluminum AA6061 and stainless steel SUS 304.

Designing of CK45 carbon steel and AISI 304 stainless steel dissimilar welds

Gas tungsten arc welding of CK45 and AISI304 stainless steel was performed through preparation of different types of samples using ER308L and ERNi-1 wires. Welded samples were studied by different techniques including optical metallography, scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction, hardness measurements and impact test. It was observed that in the buttered specimen, the structure of the weld metal was completely austenitic while the microstructure of unbuttered sample was duplex ferritic-austenitic. M23C6-type carbides were observed within the weld metal of both as-weld specimen types. Effects of different post-weld heat treatments (PWHTs) were investigated. The experimented results concluded that simultaneous grain growth and carbides precipitation were competitive during PWHT. Also, there were not any indication related to sigma-phase in as-welded and PWHTed specimens due to their lower Cr/Ni ratios and insufficient preservation times.

Study of Multi Pass Welding Temperature Distribution in Dissimilar Steels

An efficient structure design using welding of dissimilar steels is a common strategy in the process and construction industries. This study investigates the temperature distribution in the HAZ due to multi pass welding of an austenitic stainless steel SUS316 pipe to carbon steel S610 plate. A nonlinear transient thermal FE analysis is performed using ANSYS software. An APDL (ANSYS Parametric Design Language) program is developed to define moving double ellipsoidal heat source model, nonlinear thermal properties and thermal boundary conditions. Addition of filler metal is simulated using element death and birth technique. Transient effect of heat and cooling slopes during welding are studied. The present work offers a basis for future prediction of welding residual stresses and distortions in joint between pipe and plate.

Finite Element Modeling of the Inertia Friction Welding of Dissimilar High-Strength Steels

Finite element (FE) process modeling of inertia friction welding between dissimilar high-strength steels, AerMet® 100 and SCMV, has been carried out using the DEFORM™-2D (v10.0) software. This model was validated against experimental data collected for a test weld performed between the materials; this included process data such as upset and rotational velocities as well as thermal data collected during the process using embedded thermocouples. The as-welded hoop residual stress from the FE model was also compared with experimental measurements taken on the welded component using synchrotron X-ray and neutron diffraction techniques. The modeling work considered the solid-state phase transformations which occur in the steels, and the trends in the residual stress data were well replicated by the model.

Influence of Weld Parameter on Penstock Joint of B610CF-16MnR Steel

Weld parameter is an important factor affecting micrographic structure and mechanical properties of weld joints. It was investigated by metallographic experiments and mechanical property experiments for the influence of weld heat input on dissimilar steel weld joint of penstock using B610CF and 16MnR steel in water conservancy and hydropower engineering using shielded metal arc welding method and mixed active gas arc welding method. Metallographic experimental results show that in weld metal with the increase of weld heat input the quantity of bainite decreases and crystalline grain is larger when using the same welding method; but in both B610CF and 16MnR steel heat affected zone, there is no distinct difference in microstructure. Mechanical property experimental results show that in weld metal with the increase of weld heat input the impact toughness decreases when using the same welding method, but in both B610CF and 16MnR heat affected zone, there is less difference in impact toughness; and there is no distinct difference in tensile strength and plasticity of weld joint. So moderate weld heat input is recommended.

Laser beam welding of dissimilar ferritic/martensitic stainless steels in a butt joint configuration

This paper investigates laser beam welding of dissimilar AISI430F and AISI440C stainless steels. A combined welding and pre-and-postweld treatment technique was developed and used successfully to avoid micro-crack formation. This paper also examined the effects of laser welding parameters and line energy on weld bead geometry and tried to obtain an optimized laser-welded joint using a full factorial design of experiment technique. The models developed were used to find optimal parameters for the desired geometric criteria. All the bead characteristics varied positively as laser power increased or welding speed decreased. Penetration size factor decreased rapidly due to keyhole formation for line energy input in the range of 15–20kJ/m. Laser power of 790–810W and welding speed of 3.6–4.0m/min were the optimal parameters providing an excellent welded component. Whatever the optimization criteria, beam incident angle was around its limiting value of 15° to achieve optimal geometrical features of the weld.

Austenitic and ferritic stainless steel dissimilar weld metal evaluation for the applications as-coating in the petroleum processing equipment

The current study presents some fundamental observations on the effects of the welding heat input in the chemical composition, microstructure, hardness and petroleum corrosion resistance of the fusion zone, formed by the AWS E309MoL austenitic stainless steel covered electrode and the AISI 410S ferritic stainless steel, being a dissimilar welding procedure. Such welding configurations are widely used as an overlay of equipment in the petroleum and gas industries. The welds were performed with the application of three different levels in heat inputs (6, 9 and 12kJ/cm). Samples of the weld metals were conventionally prepared for the microstructural characterization by light microscopy and scanning electron microscopy. A corrosion test with samples immersed in heavy oil heated at 300°C, was carried out for a period of 60h. The corrosion rate was determined by the weight loss given after the aforesaid test. The fusion zone microstructure has a typical δ-ferrite acicular morphology, from which the level of δ-ferrite was duly altered with the increases of the welding heat input, due to the variations in the composition of the weld metal caused by dilution. It was also concluded that the chemical composition and the weld metal microstructure had a slight influence in the material’s corrosion rate. As a matter of fact, the corrosion rate of the weld metals evaluated herein, was considered satisfactory with few variations between the welding heat inputs duly applied.

Effects of Activating Flux on Inconel 718 Alloy and AISI 304 Stainless Steel Dissimilar TIG Welds

The purpose of this work is to investigate the effects of activating flux on the penetration, depth-to-width ratio (DWR), angular distortion and hardness of Inconel 718 alloy and AISI 304 stainless steel (SS) dissimilar welds in the tungsten inert gas (TIG) welding process. In the activated TIG (A-TIG) process, the single component fluxes such as SiO2, NiO, MoO3 and MoS2 and the mixed component fluxes that using 50 % of each single component flux to create six new mixtures were used in the experiment. The experimental results showed that the A-TIG welds coated with 100% SiO2 flux was provided with best DWR of dissimilar welds. In addition, the experimental procedure of A-TIG welding process not only produced a significant increase in penetration and DWR of weld bead, but also improved the angular distortion and hardness of Inconel 718 alloy and AISI 304 SS dissimilar welds.

High-temperature short-term tensile test and creep rupture strength prediction of the T92/TP347H dissimilar steel weld joints

After short-term tensile test at 848–923K, microstructures, fractographies and fractural mechanisms of the T92/TP347H dissimilar steel weld joints were studied. An equation of the creep rupture strength related to the short-term tensile strength of the joints was firstly derived based on the Goldenberg model [1]. In the high-temperature tensile process, the fracture location of the joints is all in the T92 side fine grained heat affected zone (FGHAZ); however, the fracture mechanism of the joints is changed from a mixed mode (normal plus shear) to a shear mode as the testing temperature risen, which was explained in terms of the stress tri-axiality theory. Moreover, an equation of the creep rupture strength of the weld joints was derived, and then the creep rupture strength of the joints was doped out, σ105873=49.0MPa. It indicates that the joints have a high reliability when used in the USC power units.