Steel Dissimilar Weld Research Articles

Phase transformation effect on residual stress development in fusion welding of dissimilar stainless steels with different thickness

Phase transformation effect on residual stress development in fusion welding of dissimilar stainless steels with different thickness

Investigation on weld forming, microstructure and mechanical characteristics of dissimilar steel GTAW under novel composite magnetic field

During dissimilar steel welding, differences in magnetic permeability and thermophysical parameters between materials result in significant disparity in heat distribution on both sides of weld and poor weld formability. To solve the welding quality problems caused by significant disparity in heat distribution, a novel composite magnetic field consisting of longitudinal magnetic field (LMF) and cusp magnetic field (CMF) is applied to dissimilar steel welding. In this study, the influence of novel magnetic field on the mechanical characteristics, microstructure, and weld formation of dissimilar steel gas tungsten arc welding (GTAW) welds was investigated. It was found that arc deflection is influenced by both the material properties and LMF. When longitudinal exciting current (IL) was 0.5A, the weld melting zone tended to be symmetrical. On the premise that IL remained unchanged at 0.5A, as cusp exciting current (IC) increased from 0A to 5A: the weld fusion zone always remained symmetrical; The arc compression degree, weld penetration, melting area of weld and weld penetration/width ratio significantly increased, while the weld width progressively reduced; The heat-affected zone's (HAZ) width of the base metals and the mean grain size in the HAZ are significantly reduced; The mean microhardness of the weld metal (WM) and tensile properties are also significantly improved. The study results enrich the research foundation on heat input regulation in dissimilar steel GTAW, providing experimental evidence and theoretical support for resolving welding quality issues caused by welding conditions with different material properties.

Effect of groove angle on residual stress and deformation of super duplex stainless steel SAF 2507 and austenitic stainless steel 316L dissimilar plasma arc welding

AbstractPlasma arc welding of super duplex stainless steel SAF 2507 and austenitic stainless steel 316L was carried out by using V‐grooves with different groove angles. In order to predict the temperature distribution during the welding process, the Simufact Welding finite element software was used to establish an equivalent heat source to simulate the plasma arc welding process. The equivalent heat source consists of Goldak heat source and conical heat source. In mechanical simulation, the elastoplastic behavior with isotropic hardening is realized. The numerical results are in good agreement with the experimental results. The results show that with the increase of groove angle, the equivalent stress, transverse residual stress, longitudinal residual stress and overall deformation of SAF 2507/316L dissimilar steel welded joint decrease gradually, and the overall deformation of the joint increases gradually. The groove angle has little influence on the equivalent stress, transverse residual stress and overall deformation, but has great influence on the longitudinal residual stress and Z‐direction deformation. Comprehensive analysis of the stress and deformation results under four groove angles shows that the groove angle is too large or too small, which has a great influence on the stress and deformation of the weldment. The groove angle of 60° is better for SAF 2507/316L dissimilar steel welding.

Experimental and simulation analysis on the effect of vibratory stress relief on impact toughness of Q345/316 L dissimilar steel welded joints

Vibratory stress relief (VSR) is residual stress relieving technology with the characteristics of green, energy-saving, and environmentally friendly. In response to the lack of research on the impact toughness of dissimilar steel welded joints under VSR, In this study, the law of the impact toughness of Q345/316 L dissimilar steel welded joints under VSR treatment is studied. Firstly, a platform-type VSR system is used to perform VSR treatment on the Q345/316 L dissimilar steel welded specimens. Secondly, Charpy impact tests are conducted on the specimens before and after VSR treatment, and the fracture morphology of the Q345/316 L dissimilar steel welded joints is observed based on scanning electron microscopy. Then, a numerical model of Q345/316 L dissimilar steel welding is established using ABAQUS finite element software, and the effect of VSR on the residual stress is analyzed based on the Hole-drilling method. Finally, based on the fracture morphology and residual stress evolution law, the mechanism of improving the impact toughness of Q345/316 L dissimilar steel welded joints under VSR is analyzed. The results show that VSR can effectively improve the impact toughness of dissimilar steel welded joints. The impact toughness of the welded joints after VSR increased by 26.2% compared to the untreated specimens. The residual stress of the specimens generally decreases, and the stress concentration phenomenon is alleviated. The fracture morphology exhibits a significant increase in toughness and an overall reduction in residual stress levels. Based on the comprehensive analysis of fracture morphology and residual stress state, it can be concluded that the reduction and homogenization of residual stress are the main reasons for the improvement of impact toughness.

Insight into the galvanic corrosion behaviour of low alloy steel A508/309 L/308 L stainless steel dissimilar metal weld at different temperatures.

Galvanic corrosion is prevalent in many dissimilar metal welds (DMW) in-service applications. Nevertheless, there is a scarcity of systematic investigations regarding the effect of different temperature conditions on the galvanic corrosion behaviour of low alloy steel (LAS)/309 L/308 L stainless steel (SS) DMW making up the reactor pressure vessel (RPV). Relevant results of this study indicate that temperature significantly affects the galvanic corrosion behaviour of LAS A508/309 L/308 L SS in simulated primary water solution. The shutdown temperature condition showed a higher influence of galvanic corrosion than the operating temperature condition. The discrepancy is ascribed to the varying difference in corrosion potential between the dissimilar metals in both conditions, which are 357 mV vs. SCE and ⁓55 mV vs. SCE for shutdown and operating temperature conditions, respectively. The specially designed immersion test simulating the actual RPV in-service environment revealed that the galvanic interaction between the dissimilar metals at the interface region is greatly affected by the anode (LAS A508) to cathode (309 L/308 L SS) area ratio, with average corrosion exceeding 0.3 mm/y occurring when the actual anode to cathode area ratio exceeds 1:6000. Finally, from the morphological evolution results it is seen that galvanic corrosion develops along the weld fusion line interface, rather than in the depth direction of the LAS A508, which is conducive for the operational reliability of the RPV.

Evaluation of Corrosion Resistance of GTAW API 5L X60 Steel / 2205 Duplex Stainless Steel Dissimilar Welds Produced with Different Heat Inputs.

Evaluation of Corrosion Resistance of GTAW API 5L X60 Steel / 2205 Duplex Stainless Steel Dissimilar Welds Produced with Different Heat Inputs.

Characteristics and Weldability of Resistance Plug Welding of Dissimilar Steels

Characteristics and Weldability of Resistance Plug Welding of Dissimilar Steels

An experimental investigation on predicting the fracture toughness distributions in ferritic-austenitic stainless steel dissimilar metal welds from spherical indentation tests

This study provides an experimental investigation on predicting the fracture toughness distributions in dissimilar metal welds (DMWs) connecting the nozzle of reactor pressure vessel (made of low-alloy steel) and the safety end of pipes (made of stainless steel). Indentation energy to fracture model with three criteria (namely the critical stress, critical strain, and critical damage variable, CDV) and the energy release rate (ERR) model were introduced into fracture toughness predictions from spherical indentation tests (SITs). It was found that consistency of the fracture toughness KIC calculated from the repeated tests using the critical strain criterion and ERR model is even higher than that from mini-CTs, while high dispersion predictions were observed in critical stress criterion. Compared with the CDV criterion, the ERR model focuses on the dissipation energy required to form unit area “equivalent-crack” (i.e., the rate) rather than the whole indentation energy till a critical depth, and thus it is less affected by the absolute value of damage variations in three repeated SITs. Source of errors were first investigated through the damage developments in uniaxial tensile specimens manufactured from different zones of the DMWs, which proves the CDV varies from 0.1 to 0.25 and thus shall not be regarded as a constant. Then, SEM observations were conducted on both the fracture surfaces from mini-CTs and the section surfaces from SITs, indicating both the changes in fracture mechanism (from ductile dominated to the joint effort of ductile void developments and cleavage micro-crack propagations) and the existence of small initial voids from welding lead to the errors in damage-mechanics-based predictions.

Enhancement of the Microstructure and Mechanical Properties of 1020 Carbon Steel and AISI 304 Stainless Steel Dissimilar Weld Using Different Post-Weld Heat Treatments

In order to improve the microstructure and mechanical properties of gas metal arc dissimilar weldment of AISI 304 and 1020 carbon steel, different post-weld heat treatment (PWHT) processes including annealing, tempering and normalizing were performed. The post-tempered weldment exhibited improved grain refinement over the as-welded. The as-welded joint is characterized with the formation of hard martensitic phase and CrC precipitates while the post-weld heat treated (PWHTed) joints consist more of softer ferritic phase. The PWHTs resulted in the weldment hardness reduction with post-annealed demonstrating the least hardness. Only the post-tempered weldment demonstrated improved tensile strength (~5.2%) over the as-welded (421 MPa). All the PWHT processes resulted in improved elongation (i.e., ductility) and impact energies over the as-welded. While the entire PWHTed weldments demonstrated ductile fracture mode, the as-welded sample exhibited a combination of ductile and brittle fracture mode after the tensile test.

The technology of arc welding of dissimilar steels

Arc narrow gap welding of the 35L carbon cast steel (cast carbon steel J03502, grade 1) and the 110G13L high-manganese steel (austenitic manganese steel, ASTM A128) is performed using chromium-nickel-manganese wires in a shielding gas mixture (GOST R ISO 14175–2010 – M21). The welded samples are examined by different methods including optical metallography, hardness measurement, and mechanical tests. The weld metal structure along the weld height in the welded samples proves to be fairly uniform, namely austenite with ferrite inclusions. The experiment results show that the mechanical properties of the weld metal correspond to the intermediate values for the joined steels. The developed technology has made it possible to produce a welded joint with high mechanical properties and a ductile structure.

Structural Integrity Assessment of Inconel 617/P92 Steel Dissimilar Welds Produced Using the Shielded Metal Arc Welding Process

Structural Integrity Assessment of Inconel 617/P92 Steel Dissimilar Welds Produced Using the Shielded Metal Arc Welding Process

Microstructural and Performance Analysis of TP304H/T22 Dissimilar Steel Welded Joints.

In the power plant boiler industry, dissimilar steel welding is widely used in the connection of thermal power generation units. As an important component of the unit, research on the organizational properties of dissimilar steel welded joints has significant guidance for the life design of the joint. For the long-term service state of TP304H/T22 dissimilar steel welded joints, the microstructure's morphological evolution, the microhardness, and the tensile properties of tube samples were analyzed using tests and numerical simulations. The results show that the microstructure of each part of the welded joint was free of damaged features, such as a creep cavity and intergranular cracks. The microhardness of the weld was higher than that of the base metal. In the tensile test, the welded joints broke at the weld metal at room temperature and at the side of the TP304H base metal at a temperature of 550 °C. The tensile fracture morphology demonstrated a change from a ductile fracture to a hybrid fracture when the temperature rose. The fusion zone and base metal on the TP304H side were the stress concentration areas of the welded joint, which easily sprouted cracks. This study holds significant reference value in assessing the safety and reliability of dissimilar steel welded joints in superheater units.

Intelligent Testing and Analysis of Dissimilar Steel Welds for Industrial Throttle Flowmeter

The throttling flowmeter used in utility boilers has been used as a measuring instrument for a long time. However, its safety performance, such as welding, lacks enough attention. The manufacturing welds of the throttling flowmeter are welded with austenitic stainless steel and pearlitic heat-resistant steel. Cracks and other defects are generally found in the inspection and detection of the manufacturing welds of throttling flowmeters in service, which have serious potential accidents. To find out the relationship between weldingdissimilar steels and defects, the microhardness indentation method was used to measure the residual stress of welding. Combined with the self-developed calculation software of microscopic indentation residual stress distribution, we used the difference between the color of the indentation area and the surrounding area to quickly measure the indentation strain collected by the microscope using the computer image recognition algorithm, which greatly improved the accuracy and speed of the microscopic indentation residual stress test. The results show that the residual stress at the weld of dissimilar steel is relatively large, and the mechanical property test is generally unqualified. The microindentation residual stress analysis method based on computer image recognition is used to quickly, intuitively, and accurately reveal the direct relationship between the combination of dissimilar steel welding materials and the generation of cracks and other defects.

Structural integrity assessment of Inconel 617/P92 steel dissimilar welds for different groove geometry

The work is focused on examining the effect of the weld groove geometry on microstructure, mechanical behaviour, residual stresses and distortion of Alloy 617/P92 steel dissimilar metal weld (DMW) joints. Manual multi-pass tungsten inert gas welding with ERNiCrCoMo-1 filler was employed to fabricate the DMW for two different groove designs: Narrow V groove (NVG) and Double V groove (NVG). The microstructural examination suggested a heterogeneous microstructure evolution at the interface of the P92 steel and ERNiCrCoMo-1 weld, including the macrosegregation and element diffusion near the interface. The interface structure included the beach parallel to the fusion boundary at the P92 steel side, the peninsula connected to the fusion boundary and the island within the weld metal and partially melted zone along Alloy 617 fusion boundary. An uneven distribution of beach, peninsula and island structures along the fusion boundary of P92 steel was confirmed from optical and SEM images of interfaces. The major diffusion of the Fe from P92 steel to ERNiCrCoMo-1 weld and Cr, Co, Mo, and Ni from ERNiCrCoMo-1 weld to P92 steel were witnessed from SEM/EDS and EMPA map. The Mo-rich M6C and Cr-rich M23C6 phases were detected in inter-dendritic areas of the weld metal using the weld’s SEM/EDS, XRD and EPMA study, which formed due to the rejection of Mo from the core to inter-dendritic locations during solidification. The other phases detected in the ERNiCrCoMo-1 weld were Ni3(Al, Ti), Ti(C, N), Cr7C3 and Mo2C. A variation in the microstructure of weld metal from top to root and also along the transverse direction in terms of composition and dendritic structure and also due to the composition gradient between dendrite core and inter-dendritic areas, a significant variation in hardness of weld metal was observed from both top to root and also in the transverse direction. The peak hardness was measured in CGHAZ of P92 while the minimum was in ICHAZ of P92 steel. Tensile test studies of both NVG and DVG welds joint demonstrated that failure occurred at P92 steel in both, room-temperature and high-temperature tensile tests and ensured the welded joint’s applicability for advanced ultra-supercritical applications. However, the strength of the welded joint for both types of joints was measured as lower than the strength of the base metals. In Charpy impact testing of NVG and DVG welded joints, specimens failed in two parts with a small amount of plastic deformation and impact energy of 99 ± 4 J for the NVG welds joint and 91 ± 3 J for the DVG welded joint. The welded joint met the criteria for boiler applications in terms of impact energy (minimum 42 J as per European Standard EN ISO15614-1:2017 and 80 J as per fast breeder reactor application). In terms of microstructural and mechanical properties, both welded joints are acceptable. However, the DVG welded joint showed minimum distortion and residual stresses compared to the NVG welded joint.

Numerical simulation of the temperature field of T2 copper/304 steel dissimilar metal electron beam welding

ANSYS workbench finite element analysis software was adopted to simulate and study the thermal process of electron beam welding of T2 copper and 304 steel heterogeneous materials in this paper. A solid model was established according to the size of the specimens, and a double ellipsoidal moving heat source model of the temperature field of the specimens of the three-dimensional dynamic simulation was imposed. Copper and steel welding transient temperature field distribution pattern and molten pool morphology were studied, and the temperature field welding thermal cycle curve was analyzed. The results show that the peak temperature of the steel side is higher than the copper side, the morphology of the welding pool is basically biased toward the steel side, and the highest temperature during the welding process appears in the center of the weld on the steel side about 0.5 mm.

Parameter optimizations of GMAW process for dissimilar steel welding

Parameter optimizations of GMAW process for dissimilar steel welding

Type IV Damage Evolution during Creep of 316LN SS-P91 Steel Dissimilar Weld Joint

Type IV Damage Evolution during Creep of 316LN SS-P91 Steel Dissimilar Weld Joint

Unbalanced thermal field assisted thermo-compensated resistance brazing welding 6061 aluminum alloy to 304 stainless steel

The reliable Al/steel resultant welded joint with a large contact area was of great significance in electrolysis cells to produce aluminum. Herein, a large-area 6061 aluminum alloy/304 stainless steel dissimilar welds were successfully obtained by unbalanced thermal field assisted thermo-compensated resistance brazing welding(abbreviated as UTC-TC-RBW). In the present study, the heating distribution conditions of the joint were adjusted based on the introduction of the auxiliary welding current, forming an unbalanced temperature field. The whole welding temperature field of the joint was improved significantly with the increase of the auxiliary current, which promoted the interdiffusion of Al and Fe elements at the interface. Hence, the connection area between Al alloy and steel was increased gradually. The final interface between Al alloy and steel was changed to the Al(s.s) diffusion layer and Fe2Al5 layer. XRD results proved the presence of these phase compositions. When the auxiliary current was 0.3 kA, the maximum thickness of the Al(s.s) diffusion layer and Fe2Al5 layer reached 5.25 μm and 0.86 μm. The final load of the obtained joint with the auxiliary current of 0.3 kA was the maximum and reached 1789.7N, which was approximately 3 times that of the joints without auxiliary current.

An incremental indentation energy method in predicting uniaxial tensile properties of ferritic-austenitic dissimilar metal welds from spherical indentation tests

Based on the expanding cavity model and energy analysis, an analytical derivation was first conducted to develop a correlation between the increment of elastic and plastic portions of external work and the von Mises stress-strain increment, yielding an incremental indentation energy method (IIEM) to determine the stress-strain relationship from spherical indentation tests (SITs). The IIEM has two potential approaches in determining the proportional limit, one from indentation plastic zone radius rp measurements and the other from trial-and-error. Through an application of digital image correlation on the various zones of ferritic (SA508Gr.3Cl.1) to austenitic stainless steel (316L) dissimilar metal welds (DMWs), it was found that the rp measurements is capable for the two bases, but failed in the other six zones due to the inhomogeneous characteristic of DMWs. In this case, the mean strain development of indentation plastic zone was extensively investigated through systematic finite element analysis to establish an IIEM independent of rp measurements. Solidarity of the IIEM was verified through experiments on the eight representative zones of DMWs, and compared with its previous counterpart (the empirically concluded Kwon method). It was found that the IIEM can restrain errors caused by the compensation effect in reverse predictions, leading to more accurate strength predictions (with a maximum error 9.85%). This study is expected to provide a convenient and reliable approach for predicting the uniaxial tensile properties from SITs, especially when the rp measurement is not applicable.

Microstructure and Properties of Press-Bonded Dissimilar Stainless Steel and Mild Carbon Steel Ingots

Dissimilar steel welds between stainless and mild steels are necessary for the efficient utilization of stainless steels in construction. In the present work, a dissimilar large-sized steel ingot was fabricated by press bonding a Q235 steel to a SUS 304 steel at 1100–500 °C. The microstructure of bonded interfaces has been characterized by scanning electron microscopy, electron probe microanalysis, and transmission electron microscopy, together with tensile tests to evaluate the bonding strength. It has been demonstrated that a strong-bonded, high-quality, dissimilar steel ingot could be fabricated by press bonding. The (Fe, Cr)3C carbide is present in the narrow zone of diffusion-bonded stainless steel and mild steel. Interestingly, the maximum hardness is not too high to make the transition zone brittle but enough to constrain the narrow soft ferrite during tensile and fatigue tests, causing the final fracture to occur in the mild steel region rather than the bonding interface.