Weld Heat Research Articles

A CRITIC-BPNN APPROACH TO FRICTION STIR WELDING PARAMETRIC SELECTION AND PREDICTION USING AA6082-T6 MATERIAL

The uncontrolled friction stir welding heat generation impacts the quality of welds. However, the intuition and experience of the engineer fail to regulate the effects of excessive heat generation on the weld quality and research has not addressed this aspect yet. This paper fills the gap by introducing an integrated CRITIC-BPNN (CRiteria Importance Through Intercriteria Correlation-Back Propagation Neural Network) method to investigate the selection and optimisation characteristics of the friction stir welding process for AA6082-T6 material. In this study, two major performance characteristics i.e. ultimate tensile strength (UTS) and percentage elongation (%EL), were chosen for analysis. The input parameters for the machining were the tool rotational speed, welding speed, tool pin profile and tool shoulder diameter. For the back propagation neural network model, a four-layer network with sigmoid hidden neurons and output neurons was selected. The weight estimates of the friction stir welding parameters are determined by the CRITIC method. For further weight determination between the nodes and edges of the neural networks, the Poisson distribution model was introduced. This stochastic-based method was used to calculate the weights at the edges, between the inputs, hidden layers and outputs of the neural network. The forward pass and backward passes are then used for updating and error minimisation. The welding speed has the highest weight with a contribution of 49.72% using the CRITIC method, implying that welding speed is the best and most influential parameter of the friction stir welding process. For the 4-1-2 neural network architecture, the values of the ultimate tensile strength and percentage elongation at the optimal thresholds are 0.6457 and 0.6019, respectively, for the first forward pass and 0.6123 and 0.6356, respectively, for the second forward pass. The predicted tensile strength is 320.64 MPa and the prediction for the percentage elongation is 18.83%. The results obtained from the proposed method could be useful for planning purposes during the friction welding process.

Influence of heat input and heat exchange coefficient on temperature and stress field of a X80 steel pipeline repair-weld root pass of a type-B sleeve

Abstract The formation of the type-B sleeve repaisring root pass seriously affects the quality of in-service repair of B-type sleeve. Therefore, it is necessary to systematically study the temperature field, stress field, and deformation field of type-B sleeve repairing root pass. In this paper, a double ellipsoid heat source model is developed to investigate the weld temperature, residual stress, and deformation field characteristics in the type-B sleeve repairing root pass. The results show that the heat exchange coefficient of the inner wall of the pipeline has a relatively small impact on the penetration depth, residual stress, and deformation of type-B sleeve repairing root pass, and the weld heat input has a significant impact on the penetration depth, residual stress, and deformation of type-B sleeve repairing root pass. In a whole, when the heat input of the repairing root pass is around 0.9 KJ mm−1, a well-formed repairing root pass with moderate residual stress and minimal deformation can be obtained.

Microstructure and Corrosion Behaviors of Gas Tungsten Arc Welds for Borated Stainless Steel Using Various Filler Metals

In this study, the microstructure and corrosion behavior of gas tungsten arc (GTA) welds of borated stainless steel (BSS) with a boron content of 1.62 wt.% were investigated using various filler metals. The filler metals used in this study were 308L, 309L, and 310 without the B component. A small amount of the B component was observed in the weld metal (WM) of all specimens, even though none of the filler wires contained boron. This result was caused by the dilution of the B component from the BM into the WM by the welding heat. The segregation of boron in the WM resulted in Cr-depleted areas, which negatively affected the corrosion resistance of the welded specimens. The corrosion resistance of 308L WM with the highest fraction of B components was the most deteriorated, whereas 309L WM with the lowest boron content exhibited the best corrosion resistance. Using a filler metal without the B component is expected to effectively improve the weldability and corrosion resistance of BSS; however, it can also reduce the neutron absorption capacity. Therefore, for BSS to be used as a spent nuclear fuel storage container material, the boron content of the filler metal must be carefully considered. This study provides a foundation for research aimed at improving the development and applicability of filler metals in borated stainless steel and makes it competitive for application in fourth-generation nuclear power systems.

Effect of Post Weld Heat Treatment on Microstructure and Creep Property of the TLP Bonded Ni-Based Superalloy

Effect of Post Weld Heat Treatment on Microstructure and Creep Property of the TLP Bonded Ni-Based Superalloy

Numerical Analysis of Welding Heat Source Temperature Field

Numerical Analysis of Welding Heat Source Temperature Field

Dimensional Analysis and Validity of Uniaxial Residual Stress Distribution for Welded Box Sections

This paper investigates the residual stresses induced by metal inert/active gas (MIG/MAG) welding in normal strength steel box sections, focusing on the validity of uniaxial residual stress assumption. Advanced manufacturing simulations are conducted using deterministic uncoupled transient thermomechanical analysis with a double-ellipsoidal heat source model, employing 8-node solid elements and material models calibrated for extreme temperatures per EN 1993-1-2. A comprehensive parametric analysis investigates the effects of primary welding variables, such as heat source power and welding speed, alongside geometric parameters of the heat source model using random Latin hypercube sampling technique in the analyzed parameter set. The relationship between the size and shape of the characteristic isotherms, i.e., the aspect ratio and the Rosenthal number, underscores that the analyzed welding heat sources are in the fast regime with the validity of uniaxial residual stresses based on the analytical assumption (minimal values are AR = 9.94 and Ro = 30.47). The validity and limitations of uniaxial residual stress assumptions for 59 welded and 51 heated box sections are critically evaluated by using the finite element model-based stress triaxiality parameter. Results confirm that longitudinal residual stresses dominate typical MIG/MAG welding applications, supporting the application of uniaxial residual stress models in advanced structural design by neglecting in-plane and through-thickness residual stresses. Conversely, three-dimensional residual stress state dominates under conditions such as preheating or thermal straightening.

Characterization of microstructure and mechanical performance in fiber laser welded modified 9Cr–1Mo steel for power plant applications

The current study involved butt welding 9Cr–1Mo creep strength enhanced ferritic steel, which is microalloyed with vanadium, niobium, and molybdenum, utilizing a fiber laser welding process. The main contribution is the successful application of fiber laser welding to achieve full penetration welds with minimized heat-affected zone. This study aims to assess the room temperature microstructural features and mechanical attributes of fully penetrated fiber laser welds, with an emphasis on their applicability in power plant settings. A key finding is the attainment of complete penetration welds with a notably low heat input of 75 J/mm, accompanied by a minimum top bead width of 1.2 mm and a minimal heat-affected zone measuring 0.363 mm in width. The development of an untempered lath martensite structure, accompanied by the total dissolution of precipitates resulting from the autogenous characteristics of laser welding, has demonstrated an average hardness of 502 HV0.3 within the fusion zone. The process of post weld heat treatment has led to the formation of M23C6 and MX-type precipitates, resulting in a hardness value of 252 HV0.3 and a notable decrease in internal grain strain. The evaluation of root and face bend tests demonstrated outstanding ductility in the weld joints, confirming their structural integrity. The specimens, both as-welded and post-weld tempered, demonstrated average tensile strength and impact toughness values of 773.6 MPa and 64.66 J, as well as 661 MPa and 104.33 J, respectively. These results exceed the minimum specified criteria of 585 MPa and 47 J necessary for use in power plants.

Integrated Prediction of Gas Metal Arc Welding Multi-Layer Welding Heat Cycle, Ferrite Fraction, and Joint Hardness of X80 Pipeline Steel

X80 pipeline steel is widely used in oil and gas pipelines because of its excellent strength, toughness, and corrosion resistance. It is welded via gas metal arc welding (GMAW), risking high cold crack sensitivities. There is a certain relationship between the joint hardness and cold crack sensitivity of welded joints; thus, predicting the joint hardness is necessary. Considering the inefficiency of welding experiments and the complexity of welding parameters, we designed a set of processes from temperature field analysis to microstructure prediction and finally hardness prediction. Firstly, we calculated the thermal cycle curve during welding through multi-layer welding numerical simulation using the finite element method (FEM). Afterwards, BP neural networks were used to predict the cooling rates in the temperature interval that ferrite nuclears and grows. Introducing the cooling rates to the Leblond function, the ferrite fraction of the joint was given. Based on the predicted ferrite fraction, mapping relationships between joint hardness and the joint ferrite fraction were built using BP neural networks. The results shows that the error during phase fraction prediction is less than 8%, and during joint hardness prediction, it is less than 5%.

Crystallographic texture before and after post weld heat treatment of high-frequency electric resistance welded API X65 linepipe

The microstructure and crystallographic textures of API X65 grade linepipe steel were studied in the base metal, the weld interface after high-frequency electric resistance welding (HF-ERW), and the weld interface following post-weld heat treatment (PWHT). Optical microscopy, scanning electron microscopy (SEM), and electron-backscattered diffraction (EBSD) were used to study the microstructure and texture evolution and correlated with Charpy V-notch impact toughness. The Charpy values were 172.9 ± 5.2 J for the base metal, 7.5 ± 1.6 J for the as-welded weld interface, and 69 ± 24 J after PWHT, with the latter still significantly lower than the base metal. Base metal showed a low fraction of low-indexed cleavage planes at about 9% and major texture components were (113)[110], (112)[110], and (332)[113]. In the as-welded condition, major intensities of rotated Cube (001)[110] and Goss (110)[001] texture components were observed near the weld interface. Although PWHT reduced the texture intensities, rotated Cube and Goss components were still observed. The fraction of cleavage planes was about 44% for the as-welded and about 30% for the PWHT-ed weld interface. Clearly, PWHT has reduced but not eliminated the detrimental rotated Cube and Goss textures at the weld interface. These detrimental textures likely have contributed to the low Charpy toughness after welding and continuing after PWHT.

PROPERTIES OF JOINTS WELDED USING THE MAG METHOD S355J2+N STEEL AFTER PEENING PROCESS

The aim of the research was to determine the impact of peening of each weld on the properties of a butt joint made of S355J2+N steel welded using a ceramic washer. The welding process was carried out using the MAG method on a robotic station. The analysis was based on a comparison of three butt joints: after welded, with peening of each bead and with post weld heat treatment – stress relief annealing. High frequency peening (90Hz) of each bead made was intended to reduce stress in the weld joint by introducing compressive stress into it. A Weld Line 10 pneumatic hammer was used. Tests such as visual, penetration, radiographic and destructive tests (macroscopic, transverse tensile test, transverse bending test, impact strength test, hardness) are conducted on the test samples prepared in the MAG process. The test results are compared to the acceptance values from the ISO standard. Additionally, stress measurements were made using the Barkhausen effect based on the research procedure of the technology supplier. The research performed showed that use of high – frequency peening after each bead did not affect the negative results of all the required tests during the qualification of the welding technology of S355J2+N steel compared to the test plates (after welded and after post weld heat treatment – stress relief annealing).

The Effect of Post Weld Heat Treatment in Multi Layer Welding on Tensile Strength and Hardness

Post weld heat treatment is heating objects in the furnace to certain temperatures and times after the object has been welded. PWHT is expected to reduce residual stress on objects due to the welding process. In this case, we warm up annealing (holding in a furnace) at a temperature of 750 °C with a heating time of 40 minutes. We use MIG welding (metal inert gas) and a metal filler FS 705-6 with a diameter of 0.8 mm, with a total of 3 layers. First, the object will be formed according to the standard and welded in three layers with MIG welding. Then, the object will be cut and formed according to the tensile test standards, after which the tensile test and hardness test will test it to determine the mechanical characteristics of the object. From the testing that has been carried out, it is known that objects without PWHT have a higher stress and hardness value than objects with PWHT, with a stress value of 346.57 MPa and the highest hardness value of 93.5 HRB at the 3rd welding point. However, objects with PWHT have higher elasticity and strain values, with an elasticity value of 3.32 MPa, and the strain value of objects with PWHT is 13.1.

ANALYSIS OF FRICTION STIR WELDING JOINTS ON HIGH DENSITY POLYETHYLENE (HDPE) DUE TO CHANGE IN MATERIAL TEMPERATURE AND SPINDLE ROTATION

Friction stir welding (FSW) can be a solution in solving the problem of joining thermoplastic polymers which are difficult to do with fusion welding. Selection of the proper FSW connection parameters can produce optimal connection quality in HDPE material joints. In friction stir welding, the heat of welding is used to raise the temperature of the material from its initial state to the solid state temperature. If the material temperature (T0) is increased above room temperature (TRoom), while the FSW welding parameter is constant, then at a certain increase in T0 it will produce excess welding heat which results in excessive softening or even melting of the material being welded. Therefore, the material temperature setting (T0) becomes an important parameter FSW The process of connecting the HDPE plates with friction stir welding was carried out by varying the material temperature (T0 ) of TRoom, 50 0C, 75 0C and 100 0C. While the spindle rotation varies 2000 rpm and 2500 rpm. Other parameters controlled include the type of square butt joint, 5 mm HDPE plate thickness, 20 mm/min feed rate, 0.1 mm plunge depth, 20 mm tool shoulder diameter, 4.5 mm pin length and 6 mm pin diameter. The result is that the higher the spindle rotation and the material temperature during the welding process causes the FSW peak welding temperature to increase. The highest peak weld temperature was obtained at variations in material temperature (T0) 100 °C with a spindle rotation of 2500 rpm, which is 123.2 °C or 94% of the melting temperature of HDPE. The hardness of the weld nugged area is still lower than the hardness of the base material. The highest average tensile strength of the research variations was achieved at a spindle rotation speed of 2500 rpm and a material temperature of 75 °C of 16.8 MPa, higher than the average tensile strength of the base material which is 15.1 MPa.

Documenting weld pool behavior differences in variable-gap laser self-melting and wire-filling welding of titanium alloys

In large-scale welding processes involving complex geometries, variations in gap dimensions and the transition of filler wire form distinctive molten pool flow behaviors, significantly affecting weld formation and quality. This paper investigates the differences in the laser self-melting and wire-filling welding pool behavior of titanium alloy with variable gaps through both simulation and experimentation. An innovative three-dimensional transient heat-flow coupling model is developed to simulate laser welding with variable gap structures, incorporating the dynamics of the welding wire-filling process. The different laser welding modes and the filling process under the variable gap structure were numerically simulated. The results indicate that the maximum flow rate of the laser self-melting pool remains stable in proximity to the keyhole, reaching a maximum of approximately 2.491 m/s, with molten metal entering through the area surrounding the keyhole. As the gap size gradually increases to 0.2 mm during the laser self-fusion welding stage, keyhole instability becomes more pronounced. In transitioning from laser self-fusion to wire-filling welding, the welding wire behavior can be divided into three stages. The molten metal at the end of the welding wire is transferred to the liquid melt pool through a liquid metal bridge. The flow rate of this bridge initially rises before gradually decreasing, reaching a maximum flow rate of 1.606 m/s. Notably, the welding wire lags approximately 0.6 mm behind the laser's focal point, with the narrowest width of the liquid bridge measuring about 0.89 mm. Based on the simulation results and considering the melting transition time of the welding wire, the initiation time for the welding wire has been further adjusted to the first 10 ms when the gap threshold reaches 0.2 mm. Experimental verification confirms the successful laser welding of a 2 mm variable gap structure thin plate. This study elucidates the melt pool flow, keyhole fluctuations, and metal transition behaviors during the laser welding process, contributing to a deeper understanding of the complex heat and mass transfer dynamics inherent in variable gap structure laser self-melting and wire-filling welding. Ultimately, these insights aim to enhance the application of laser welding in adaptive welding for large structural components.

Influence of the welding thermal cycle on δ-ferrite evolution in the first layer of austenitic stainless steel (ASS) 308L produced by WAAM-GTAW

In this article, the effects on the weld bead geometry and heat affected zone at observe area explored on Wire Arc Additive Manufacturing Gas Tungsten Arc Welding (WAAM-GTAW). Based on GTAW process, layer by layer WAAM components are produced by deposition welding. Each welding process, the temperature is recorded at one point to determine temperature history. This article explained how specific thermal cycles, from the welding heat input to subsequent cooling phases, dictate the transformation behavior, phase stability, and morphological changes in δ-ferrite, ultimately shaping the material properties and performance of the welded. The factor affecting these properties were explained to identify evolution microstructure in observe area. The paper focuses on the impact of the temperature history to determine macrostructure and microstructure δ-ferrite evolutions of the observe parts deposited in the WAAM process. The thermal cycle experienced during welding lead to the transformation of δ-ferrite into austenite. The δ-ferrite transforms in austenite when the temperature rises above 800 °C–450 °C (T 8/5). Specimens that experienced temperatures above T8/5 exhibited vermicular (V) and eutectic ferrite (EF) modes of delta ferrite. Specimens that had peak temperature prediction records around 750 °C–525 °C in the T8/5 area exhibited ferrite with acicular (Ac) mode. Specimens approaching the lower line of T8/5 around 425 °C showed a transition from acicular to coarse Ac. Specimens with peak temperature records below the T8/5 line generally did not experience changes after the welding process.

Effect of Process Parameters on the Mechanical Properties of Simultaneous Double-Sided Friction Stir Welding Joints

Currently, conventional single-sided friction stir welding is primarily suitable for joining thin plate aluminum alloys, and its application to thick plates is still challenging in terms of welding efficiency and joint mechanical properties. Simultaneous double-sided friction stir welding (SDS-FSW) is a high-efficiency joining technique specifically developed for welding thick plates. However, there is little research on the influence of SDS-FSW process parameters on the joint mechanical properties. In this study, a 12 mm thick AA6061-T6 aluminum alloy and dual robot welding equipment are used to conduct SDS-FSW experiments exploring the influence of rotational speed ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} and welding speed v on the mechanical properties and microstructure. The results show that when the welding parameters are ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} = 800 r/min and v = 60–80 mm/min, smooth and defect-free thick plate aluminum alloy SDS-FSW joints can be obtained, and the macroscopic morphology of the joints is distributed in a “dumbbell” shape. The grain size in the weld nugget zone increases with increasing welding heat input. The microhardness distribution in the joint displays a “W” shape, and the hardness value of the weld nugget zone can reach 67% to 86% of that of the base metal (BM). The junction between the thermo-mechanically affected zone and the heat affected zone is the weakest region of the joint, with the lowest hardness being approximately 51% of that of the BM. When the welding parameters are ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\omega$$\\end{document} = 800 r/min and v = 140 mm/min, the SDS-FSW joint has the highest tensile strength, reaching 78.43% of the BM strength and exhibiting ductile fracture characteristics. This research indicates that acceptable weld strength in thick aluminum alloys can be achieved via the SDS-FSW joining mechanism, highlighting its significant potential for industrial applications.

Enhancing resistance welding strength of carbon fiber/polycaprolactam thermoplastic composites through coupling agent‐modified metal heating elements

AbstractThis study investigates the impact of coupling agent‐modified resistance welding heating elements on the welding strength of carbon fiber‐reinforced polyamide 6 (PA6) thermoplastic composites. Silane coupling agent KH550 and titanate coupling agent UP‐201 were used to modify heating elements made of 304 stainless steel mesh. Optimal modification parameters for KH550‐modified stainless steel mesh (SSM) were determined using orthogonal experiments, resulting in maximum single lap shear strength (LSS) of 17.05 MPa under specific welding conditions. Comparative tests demonstrated the enhancement effect of UP‐201‐modified SSM on LSS. Additionally, two experimental schemes were used to study the synergistic enhancement effect of KH550 and UP‐201 on the LSS of resistance welded joints. The findings indicate that both coupling agents improve the welding strength, with significant differences in their individual and combined effects.Highlights This study explores carbon fiber reinforced Nylon 6, an innovative thermoplastic. Analyzed effects of modified heating elements on joint shear strength. Examined silane and titanate coupling agents' effects on weld joint shear strength. Investigated synergistic effects of silane and titanate agents on weld joint strength. Investigated the synergistic enhancement mechanism of silane and titanate agents.

A novel approach to control thermal induced buckling during laser welding of battery housing through a unilateral N-2-1 fixturing principle

Battery housing (BH) in modern electric vehicles must meet demanding functional requirements. The design and geometry of the BH become intricate to prevent damage during collisions and to ensure absolute impermeability to gases and water during operation. Moreover, in the pursuit of a lightweight BH, manufacturers rely on high-strength 6xxx aluminium alloys, posing significant challenges for the welding processes. It is estimated that up to 30 m of weld length is required during the construction of battery housings including joining the lid and under-shield to the main structural frame and joining the ribs to the frame for standard vehicles. Due to the increasing use of thin sheets for lightweighting the structure, thermal-induced buckling may occur and generate critical dimensional unconformities going beyond design tolerances. This underpins the need to optimise fixturing design to control thermal-induced buckling.This paper goes beyond the state-of-the-art “N-2-1” approaches for fixturing thin and deformable parts and proposes the new principle of “unilateral N-2-1 fixturing”. The driving idea is adding unilateral restraints to the direction of thermal contraction, which ultimately causes buckling; and, keeping the direction where the thermal expansion occurs in a free state. The methodology is based on three main steps: (1) physics-based modelling of parts and fixtures using a thermo-mechanical FEA simulation; (2) calibration of the weld heat source using metallographic data; (3) validation using optical scanning technology. The methodology was demonstrated during the laser beam welding of a high-strength aluminium 6xxx thin deformable lid to a rigid high-strength 6xxx aluminium extrusion frame. Results indicated that the thermal induced buckling deformation was reduced from 15 mm, when using the state-of-the-art fixturing approach, to approximately 2 mm with the proposed methodology.

Dissimilar unbeveled aluminum to steel butt joint achieved by laser-arc hybrid welding-brazing

In this study, unbeveled butt joints of 2 mm thick steel and aluminum plates were welded using a laser-arc hybrid process. The influence of welding speed and wire feed speed on joint weld formation, microstructures, and mechanical properties were investigated. The results indicate that using a laser-arc hybrid heat source enables good weld formation of steel/aluminum dissimilar metals without groove preparation, even under high welding speed conditions. The steel side interface formed Fe₂(Al,Si)₅ near the steel and Fe(Al,Si)₃ near the aluminum. As the welding heat input decreased, the thickness of the intermetallic compounds gradually reduced. With an increase in welding speed or wire feed speed, the tensile strength of the joint first increased and then decreased, reaching a maximum of 104.47 MPa. Cracks propagated rapidly along the intermetallic compound region, resulting in brittle fracture characteristics. The three-point bending test showed a maximum longitudinal bending angle of 53.82° and a maximum transverse bending angle of 36.54°.

Analysis of the Effect of PWHT on the Corrosion Test of API 5L X65 Material in Submerged Arc Welding

This research discusses the method of making distribution pipes using the Submerged Arc Welding (SAW) welding process, especially for pipes with spiral connections. The material used is API 5L X65. SAW pipes with spiral joints are more commonly used for low-pressure piping systems. However, in certain cases, the production of SAW pipes for Sour Service distribution requires special treatment. Sour Service pipes have a high level of corrosion and residual stress, so Post Weld Heat Treatment (PWHT) is required to prevent Hydrogen Induced Cracking (HIC). HIC occurs due to the absorption and accumulation of hydrogen gas in the metal, causing the formation and growth of cracks, which is also influenced by residual stress. PWHT is applied to reduce residual stress to reduce the risk of corrosion. PWHT is a process to change the structure of the weld metal by heating the metal at a certain temperature and time. This research shows that variations in PWHT temperature produce an average residual stress that is not much different with less difference than 2%, In corrosion testing with the HIC method shows crack evidence but is still satisfactory NACE MR0175 criteria for pipe PWHT temperature variation conditions

Microstructure and mechanical-property evolution of the explosive welding joint from the same RAFM steels under explosive welding and post-weld heat treatment

This study investigated the morphological evolution behaviors and the mechanical property of the weld interface during explosive welding for the flyer plate and base plate sourcing from the same reduced activation ferrite/martensitic (RAFM) steel. The relationship between fine-grain formation and the occurrence of dynamic recrystallization was analyzed based on the strain and temperature field distributions at the explosive-weld interface. Although post-weld tempering (PWT) treatment eliminated bent martensite laths, but it did not eliminate fine equiaxed grains and δ ferrite grains near the explosive-weld interface; therefore, the PWT treatment improved the mechanical properties of the explosive-weld RAFM steel joint only minimally. However, implementation of a normalizing process after the explosive welding process (“PWN” treatment) significantly eliminated the gradient structure and the residual δ ferrite grains at the explosive-weld interface of the RAFM steel joint. Based on the PWN state, the inclusion of a tempering treatment (“PWNT” treatment) promoted the uniform precipitation of M23C6 carbides, which significantly improved the tensile strengths of the explosive-weld RAFM steel specimens under both room and high temperatures. To study the influence of different microstructures on the plastic deformation behavior at the explosive-weld interface, the representative volume element (RVE) models basing on crystal plasticity finite element (CPFEM) method was constructed for different post-weld heat treatments (PWHTs). At the explosive-weld interface of the PWT-state RAFM steel joint, the plastic deformation was mainly concentrated in the δ ferrite grains, rather than in the fine equiaxed grains. In addition, only minimal deformation concentration was observed for the PWNT-state RAFM steel joint. In order to reveal the independent influence of the fine equiaxed grains at the weld interface on the mechanical properties of explosive-weld RAFM steel joint, the microstructural and mechanical distinctions between the RAFM steel joints in the N-PWT and PWNT states were investigated detailly. Finally, through optimization of the PWHT method, an explosive-weld RAFM steel (PWNT state) joint with a uniform microstructure and ideal mechanical properties was obtained.