Metallurgical Interactions Research Articles

High-power ultrasonic spot welding of copper to type 304L austenitic stainless steel

The demand for a robust welding technique capable of joining copper and steel is driven by their extensive application across various industrial sectors. Addressing the limitations of current welding methods, this study explores the effectiveness of ultrasonic welding in joining commercially pure copper to type 304L stainless steel. The effects of different welding parameters on the characteristics of the welded joints were investigated. The results demonstrate the successful welding of the two metals without inserting an interlayer despite the metallurgical immiscibility of copper and iron. The interfacial bond density and the joint strength were found to increase with the applied welding energy. A joint strength of approximately 80% of the base copper strength was obtained. Transmission electron microscopy (TEM) analysis unveiled a well-bonded interface with excellent continuity between the two metals. A diffusion layer containing nano-sized chromium-rich oxide or intermetallic compound particles was observed. It was noticed that copper penetrated the partially disrupted chromium-rich oxide layer reaching and developing intimate contact with the newly uncoated stainless steel surface. A synergy of mechanical interlocking and solid-state metallurgical adhesion was revealed for the bonding mechanism in addition to potential metallurgical interactions at the interface.

A Comprehensive Review and Future Perspectives of Simulation Approaches in Wire Arc Additive Manufacturing (WAAM)

Abstract Wire arc additive manufacturing (WAAM) has emerged as a promising technique for producing large-scale metal components, favoured by high deposition rates, flexibility and low cost. Despite its potential, the complexity of WAAM processes, which involves intricate thermal dynamics, phase transitions, and metallurgical, mechanical, and chemical interactions, presents considerable challenges in final product qualities. Simulation technologies in WAAM have proven invaluable, providing accurate predictions in key areas such as material properties, defect identification, deposit morphology, and residual stress. These predictions play a critical role in optimizing manufacturing strategies for the final product. This paper provides a comprehensive review of the simulation techniques applied in WAAM, tracing developments from 2013 to 2023. Initially, it analyzes the current challenges faced by simulation methods in three main areas. Subsequently, the review explores the current modelling approaches and the applications of these simulations. Following this, the paper discusses the present state of WAAM simulation, identifying specific issues inherent to WAAM simulation itself. Finally, through a thorough review of existing literature and related analysis, the paper offers future perspectives on potential advancements in WAAM simulation strategies.

Numerical and experimental development of cupronickel filler brazed joints for divertor and first wall components in DEMO fusion reactor

The brazeability of a cupronickel commercial alloy (Cu10Ni) was evaluated for its use as a filler alloy for high-temperature joining of tungsten to the reduced activation ferritic/martensitic steel EUROFER 97 (W-E) and between tungsten base materials (W-W) for its application at the first wall and divertor of future fusion reactors. In addition, given the importance of the residual stresses in these heterogenous joints, a study of the brazing conditions and the impact of the selected filler has been conducted using numerical software to understand its impact on the quality of the joint.Two thermal cycles were evaluated (1165 °C and 1190 °C) and selected based on the thermal characterization of the filler alloy. The microstructural examination revealed that, in W-E joints, nickel acts as an activator element, reacting and forming interfacial layers at the EUROFER 97 - Cu10Ni interface. In the case of the W-W joints, a lower level of diffusion phenomenon and metallurgical interaction between Cu10Ni and base materials were observed. The hardness profile indicated that the hardening process of EUROFER 97 was associated with the formation of untempered martensite. On the other hand, tungsten kept the received hardness. The mechanical characterization by shear test reported similar values between both types of joints carried out at 1190 °C but different when the temperature was increased (1165 °C), associated with the brittle character of tungsten and its lower metallurgical interaction.The numerical analysis of the brazing process carried out with ANSYS software shows that residual stresses are accumulated mainly at the interfaces. The information provided by the simulation shows, for a 50 µm filler thickness, the importance of mitigating the residual stress by selecting a filler with an intermediate Coefficient of Thermal Expansion (CTE) that alleviates mechanical stresses relative to the base materials.

The Influence of Interfacial Thermal Conductance on the Tensile Strength of a Sn-Mg Solder Alloy

Sn-Mg alloys are potential Pb-free solder options. However, their mechanical strength and interfacial characteristics with electronic substrates remain barely understood. This study focuses on the interfacial heat transfer aspects, microstructure, and tensile strength of a Sn-2.1wt.%Mg alloy. Samples with various thermal histories were produced using a directional solidification apparatus. In these experiments, a Sn-2.1wt.%Mg alloy was solidified on Cu and Ni substrates, which are of interest in the electronics industry. Mathematical modeling was then employed, allowing for the determination of the overall and interfacial heat transfer coefficients (hov, and hi, respectively). The results show that the Ni substrate exhibits higher interfacial thermal conductance with the Sn-2.1wt.%Mg alloy compared to the Cu substrate, as indicated by the higher hi profiles. This fact occurs mainly due to their metallurgical interaction, resulting in a stronger bond with the presence of Sn-Ni-rich intermetallics at the interface. Finally, experimental equations based on the Hall–Petch relationship are proposed to describe how the refinement of the fibrous spacing of the Mg2Sn interphase (λG) and an increase in hi enhance both yield and ultimate tensile strengths.

Review of minimum requirements and development of guidance for weld spacing

Follow-on work to a recently completed joint industry project pertaining to hot tap branch connections included the development of guidance on minimum spacing between various combinations of adjacent pipeline girth and appurtenance welds. Related guidance was also developed for the maximum recommended length of a Type B repair sleeve. Several factors may contribute to minimum weld spacing requirements, including metallurgical, geometrical, residual stresses, and even aesthetics. It is not uncommon to hear concerns expressed about the metallurgical interaction of adjacent welds, in terms of overlapping heat-affected zones (HAZs). However, overlapping or interacting HAZs do not become a concern unless welds are spaced very closely, as HAZ widths for typical pipeline welds are generally less than 0.25 in. (6.4 mm). Often, minimum weld spacing requirements are based upon geometrical reasons, such as avoiding overlapping stress concentrations at the weld toes or allowing adequate access for inspection equipment following welding. Or, they may be based upon residual stresses, and the avoidance of overlapping residual stress fields and distortion, which are influenced by pipe dimensions and the welding procedure and could approach a few inches in distance. Finally, weld spacing requirements, especially for new construction applications, may simply be based upon aesthetics, where the flexibility exists to separate welds by a distance that makes sense from a visual perspective. Examples of company-imposed and code-based minimum requirements are provided that can used to perform a critical assessment of current company requirements or develop new requirements.

Microstructure and mechanical behavior of cemented carbide with Al alloy binder fabricated by selective laser melting

Although cemented carbides have been increasingly investigated for additive manufacture, cemented carbides with low melting point metal binders have rarely been explored. In this study, a cemented carbide with AlSi10Mg alloy binder was fabricated by selective laser melting (SLM). The processing parameters were optimized through response surface methodology (RSM). The microstructure and mechanical properties of SLMed cast tungsten carbide (CC) - 40 wt% AlSi10Mg were studied. The SLMed carbide of CC - AlSi10Mg had much finer grain size of AlSi10Mg binder as compared with that of SLMed AlSi10Mg (1.9 μm vs. 7.3 μm). Noticeable metallurgical interaction between CC and AlSi10Mg binder was observed for SLMed carbide, which enhanced the bonding strength between CC and AlSi10Mg. SLMed carbide showed good Vickers hardness (236 ± 10 HV3), compression strength (639 ± 13 MPa), and abrasion wear resistance (0.47 ± 0.03 × 10−3 mm3N−1 m−1).

Experimental investigation of laser scan strategy on the microstructure and properties of Inconel 718 parts fabricated by laser powder bed fusion

Inconel 718 (IN718) is a nickel-based superalloy which exhibits excellent tensile and impact resistant properties along with good corrosion resistance at high temperatures. However, due to the high toughness and work hardening, the machinability of this superalloy is low. Therefore, the selective laser melting (SLM) process has been adopted as an efficient technique to fabricate IN718 parts as it overcomes the problems associated with conventional manufacturing of superalloys. In the SLM process, various process parameters like scan strategy, laser power, scan speed, and energy density are defined for the fabrication to regulate the microstructure and thus control the mechanical properties like tensile strength, yield strength, impact strength, and hardness. In the SLM process, the thermal cycles induce residual stress into the part. These residual stresses can be detrimental to the microstructure and hence mechanical properties of the part. Residual stresses lead to warping of the part during the fabrication process, thereby leading to failure of the component. Although each process parameter has an independent and definitive effect on the overall mechanical and metallurgical properties, scan strategy is an independent process parameter which directly affects the level of residual stresses, microstructure, and mechanical properties of the SLM part, as the heat zones in part can be shifted from one location to another by varying the scan strategy. This variation in the area of the heat-affected zone determines the grain size ranging from equiaxed to elongated. Hence, the scan strategy is the only parameter that is varied for this study. The various scan strategies adopted here are chess, striped, flow-optimized, and customized scan strategies. In this study, the microstructural evaluation was deduced, followed by compositional analysis and hardness tests on the SLM fabricated parts. The residual stress of the parts was then determined using the hardness method. This effort was undertaken to identify the effect of scan strategy on residual stress and to discuss the metallurgical interactions between the mechanical and microstructural properties within the IN718 superalloy.

Analyzing metallurgical interaction during arc surfacing of barrier layers on titanium to prevent the formation of intermetallics in titanium-steel compounds

This paper considers a possibility to obtain high-quality butt junctions of bimetallic sheets from steel clad with a layer of titanium, with the use of barrier layers. The task that was tackled related to preventing the formation of Ti-Fe intermetallic phases (IMPs) between the steel and titanium layer. The barrier layers (height ~0.5 mm) of vanadium and copper alloys were surfaced by arc techniques while minimizing the level of thermal influence on the base metal. To this end, plasma surfacing with a current-driving wire and pulsed MAG surfacing were used. The obtained samples were examined by methods of metallography, X-ray spectral microanalysis, durometric analysis. It has been established that when a layer of vanadium is plated on the surface of titanium, a defect-free structure of variable composition (53.87–65.67) wt % Ti with (33.93–45.54) wt % V is formed without IMPs. The subsequent surfacing of steel on a layer of vanadium leads to the formation of eutectics (hardness up to 5,523 MPa) in the fusion zone, as well as to the evolution of cracks. To prevent the formation of IMPs, a layer of bronze CuBe2 was deposited on the surface of vanadium. The formed layer contributed to the formation of a grid of hot cracks. In the titanium-vanadium-copper transition zones (0.1–0.2 mm wide), a fragile phase was observed. To eliminate this drawback, the bronze CuBe2 was replaced with bronze CuSi3Mn1; a defect-free junction was obtained. When using a barrier layer with CuSi3Mn1, a defect-free junction was obtained (10–30 % Ti; 18–50 % Fe; 5–25 % Cu). The study reported here makes it possible to recommend CuSi3Mn1 as a barrier layer for welding bimetallic sheets "steel-titanium". One of the applications of the research results could be welding of longitudinally welded pipes of main oil and gas pipelines formed from bimetallic sheets of steel clad with titanium.

Comparing features in metallurgical interaction when applying different techniques of arc and plasma surfacing of steel wire on titanium

This paper reports a study into the regularities of interphase interaction, features in the formation of intermetallic phases (IMPs), and defects when surfacing steel on titanium in four ways: P-MAG, CMT, plasma surfacing by an indirect arc with conductive wire, and PAW. A general tendency has been established in the IMP occurrence when surfacing steel on titanium by all the considered methods. It was determined that the plasma surfacing technique involving an indirect arc with conductive wire is less critical as regards the IMP formation. That makes it possible to obtain an intermetallic layer of the minimum thickness (25...54 μm) in combination with the best quality in the formation of surfaced metal beads. Further minimization of the size of this layer is complicated by a critical decrease in the heat input into the metal, which gives rise to the capability of the surfaced metal to be collected in separate droplets. The formation of TiFe2, TiFe, and the α-Fe phase enriched with titanium in different percentage compositions has been observed in the transition zone of steel surfacing on titanium under different techniques and modes of surfacing. The study has shown the possibility of formation, in addition to the phases of TiFe2 and TiFe, the Ti2Fe phase at low heat input. The technique of plasma surfacing by an indirect arc with conductive wire minimizes the thermal effect on the base metal. When it is used at the border of the transition of the layer of steel surfaced on titanium, the phase composition and structure of the layers in some cases approach the composition and structure of the transition zone of the original bimetallic sheet "titanium-steel" manufactured by rolling. A layer up to 5 μm thick is formed from the β phase with an iron concentration of 44.65 % by weight and an intermetallic layer up to 0.2...0.4 μm thick, close in composition to the TiFe phase. The next step in minimizing the IMP formation might involve the introduction of a barrier layer between titanium and steel.

Effect of Returnable Material in Batch on Hot Tearing Tendency of AlSi9Cu3 Alloy.

The main reason for the use of returnable material, or recycled alloys, is a cost reduction while maintaining the final properties of the casting. The casting resulting quality is directly related to the correct ratio of commercial grade alloy and alloy made by remelting the returnable material in the batch. The casting quality is also affected by the purity of the secondary raw materials used, the shape complexity and the use of the casting itself. The presented article focuses on the effect of increasing the returnable material content in the batch on the hot tearing susceptibility of AlSi9Cu3 alloy. Hot tears are a complex phenomenon that combines metallurgical and thermo-mechanical interactions of the cast metal. Hot tearing susceptibility was evaluated on the basis of quantitative (HTS—hot tearing susceptibility index) and qualitative evaluation. The negative effect of returnable material in the batch was already manifested at a 20% content in the batch. The critical proportion of the returnable alloy in the batch can be stated as 50%. The alloy with a 50% returnable material content manifested insufficient results of the HTS index and qualitative evaluation, which means increased sensitivity to tearing. The negative effect of returnable material and the increased sensitivity were also confirmed in the evaluation of the fracture surface and hot tear profile. The microstructure of alloys with 50% and higher proportion of returnable material was characterized by a higher amount of iron phases (mainly Al5FeSi), whose sharp ends acted as critical regions of hot tearing and subsequent hot tear propagation, which had a major impact on the increase in hot tearing susceptibility.

Effects on microstructural refinement of mechanical properties in steel‑copper joints laser welded with alternating magnetic field augmentation

In this research project, pure copper and stainless steel were joined using laser beam welding in the presence of an alternating magnetic field. The microstructure, element distribution and mechanical properties of the welded joints were then analyzed using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectrometry and other methods. We determined that the microstructure in the fusion zone transformed in the alternating magnetic field improved laser welding process from bulky banded and spherical structures to fine blocky and granular structures. Grain refinement and inhibition of composition segregation were achieved with the addition of electromagnetic force generated by alternating current, reducing susceptibility to solidification cracking. During the metallurgical interaction, diffusion of solute atoms decreased the microstructure gradient significantly, reducing thermal stress and improving the mechanical properties of the welded joints. The emergence of an increased number of shear dimples in the fracture confirmed improvement in ductility. A physical model is proposed to validate the strengthening and toughening mechanisms of the laser welded joints augmented by alternating magnetic force.

Welding and Thermal Spray Processes for Maintenance of Hydraulic Turbine Runners: Case Studies

Abstract: Hydraulic runners are susceptible to failures by cracks or wear by erosion, corrosion, or cavitation. The modern runners are fabricated in carbon steel and martensitic stainless steel. Arc welding processes normally do the repair of eroded areas, or cracked parts. Each material or type of repair needs specific criteria, procedures, and precautions to guarantee their success and prevent future issues, like the recurrence of the cracks or reduction of the useful life of the runner by modifications of the original material. Wear-resistant coatings are applied by welding or by thermal spray processes, considering this last one has no metallurgical interaction with the material of the runner, keeping the original properties of the material. For several years the companies Copel GeT, Lactec, UTFPR, and UFPR collaborate on the study of different techniques, methods, and processes to repair hydraulic runners, this work aims to present a short compilation, and examples of some results obtained applied on real runners.

. Особливості металургійної взаємодії при наплавленні сталевого дроту на титанову пластину з напиленим прошарком

. Особливості металургійної взаємодії при наплавленні сталевого дроту на титанову пластину з напиленим прошарком

Metallurgical Interaction among BNi-9 and Waspaloy, FSX-414 or 304-Type Stainless Steel under TLP Cycle

The metallurgical interaction of BNi-9 filler metal paste with Waspaloy, Ni-coated Waspaloy, FSX-414, and 304-SS is studied in a brazing treatment under an argon atmosphere with an isothermal hold for one hour at 1150 °C. The Waspaloy alloys were brazed under both solubilized and aging conditions. Before brazing, some Waspaloy samples were electrochemically coated with an Ni layer 35-40 μm thick. The microstructures of the FSX-414 and 304-SS alloys showed that the thickness of the isothermal solidification zones was approximately 50 μm, while this thickness was not well defined in the Waspaloy samples. The Ni-coated solubilized Waspaloy showed a wider diffusive zone, which was associated with an increase in the penetration extension of the liquid films. The analysis of grain orientation in all brazed zones of the Waspaloy samples showed aleatory characteristics. Plastic factors in the different brazed zones were also obtained by nanoindentation under 350 mN loads. It was observed that the plastic factor was low when the width of the diffusive zone increased. The plastic factor in the Ni-coated Waspaloy was the lowest, while the diffusive zone in this sample had the largest width. The BNi-9 wettability is better in FSX-414, and 304-SS than in Waspaloy. Ni coating in Waspaloy improves BNi-9 wettability.

Embedment of eutectic tungsten carbides in arc sprayed steel coatings

Tungsten carbide reinforced deposits have already evolved into a predominant coating system in order to protect stressed surfaces against wear. Among thermal spraying processes, due to a high deposition rate, arc spraying is a promising process to manufacture cost-saving, wear resistant coatings. However, inherent process characteristics prevailing in arc spraying as well as the utilization of tungsten carbides, as a filling for cored wires, could lead to undesirable phase evolutions, which in turn provoke the degradation of the mechanical properties. The embedment of tungsten carbides into the surrounding metallic matrix is affected by metallurgical interactions with molten spray particles.Within the scope of this study, an external injection of tungsten carbides was applied in order to analyze the embedment of tungsten carbides in arc sprayed low alloyed steel. Accordingly, metallographic investigations were carried out, which address the reactive layer at the interface of embedded tungsten carbides to the surrounded iron-based matrix. Microstructural characteristics such as mechanical properties and phase composition were scrutinized by means of nanoindentation, energy dispersive X-ray spectroscopy, and X-ray diffraction, respectively. It was found that the embedment of tungsten carbides, which have been externally injected into the arc burning zone, differs from that obtained from deposits produced with the use of cored wire with tungsten carbide as filling. Thus, externally injected tungsten carbides are less inclined to form eta carbides due to dissolution, which again results in differences in the mechanical properties across the reactive layer.

Numerical simulation of resistance spot welding of Al to zinc-coated steel with improved representation of contact interactions

The resistance spot welding (RSW) process involves electrical, thermal, mechanical and metallurgical fields and contact interactions across faying interfaces. The contact interactions include mechanical, electrical and thermal contacts where the electrical and thermal conduction across the faying interface are affected strongly by the mechanical contact pressure and temperature at the interface in addition to material composition and surface conditions. However, representation of the contact interactions is often simplified with no or limited consideration of a combination of above-mentioned effects in state-of-the-art numerical simulation models due to extremely limited availability of electrical and thermal contact resistance data at various pressures and temperatures. As a result, existing numerical models, mainly to simulate the process of dissimilar RSW process like Al to steel, often have difficulties in accurately capturing the dynamic voltage response, especially during the initial stage when the contact interactions start to engage with rapid changes in interfacial temperature and pressure and in predicting progress of nugget growth and joint deformation all through the welding stage. In this study, we present an improved representation of both electrical contact resistance (ECR) and thermal contact resistance (TCR) in Al to zinc-coated steel RSW process. The calculation of ECR is based on analytical formulations and referencing experimentally measured contact resistance curves from existing literature, with multiple effects of interfacial temperature, contact pressure, zinc coating and Al oxide involved. The corresponding TCRs are obtained from the ECRs according to the Wiedemann–Franz Law for consistency. The model with the improved ECR and TCR representations is established in ANSYS, sequentially coupling mechanical field and electro-thermal field, and it is used to simulate a benchmark Al to zinc-coated steel RSW process using rounded-tip electrode where ECR and TCR are both critical respectively due to important heat generation by electrical contact resistance at preheat stage and significant imbalance of heat generation by Al sheet and steel sheet. Eventually, the simulation results provide a significantly improved prediction of the voltage response and weld profile compared to a conventional approach. It accurately captures the bulging of the steel sheet into the aluminum sheet, which was missed by previous work. The improved model is further used to study nugget development, heat generation and re-distribution and nuggets development during the whole RSW process. Finally, the temperature history at the Al–steel interface obtained from the model is used to predict intermetallic compound (IMC) growth and it accurately captures the bimodal profile of IMC thickness distribution along the Al–steel interface. Findings from the above-mentioned discussions are summarized and can be used to guide future welding schedule development or electrode geometry design for the RSW of Al to steel.

Thermomechanical characterization of joints for blanket and divertor application processed by electrochemical plating

Fusion technology requires in the fields of first wall and divertor development reliable and adjusted joining processes of plasma facing tungsten to heat sinks or blanket structures. The components to be bonded will be fabricated from tungsten, steel or other alloys like copper. The parts have to be joined under functional and structural aspects considering the metallurgical interactions of alloys to be assembled and the filler materials. Application of conventional brazing showed lacks ranging from bad wetting of tungsten up to embrittlement of fillers and brazing zones. Thus, the deposition of reactive interlayers and filler components, e.g. Ni, Pd or Cu was initiated to overcome these metallurgical restrictions and to fabricate joints with aligned mechanical behavior.This paper presents results concerning the joining of tungsten, Eurofer and stainless steel for blanket and divertor application by applying electroplating technology. Metallurgical and mechanical characterization by shear testing were performed to analyze the joints quality and application limits in dependence on testing temperature between room temperature and 873K and after thermal aging of up to 2000h. The tested interlayers Ni and Pd enhanced wetting and enabled the processing of reliable joints with a shear strength of more than 200MPa at RT.

Interplay of diffusion and phase transformations in microstructural evolution of the interaction zone between U–9 wt.% Mo and Zr–1 wt.% Nb alloys

Metallurgical interaction between U–9 wt.% Mo metallic fuel alloy and Zr–1 wt.% Nb clad material has been assessed. Interdiffusion of constituent elements across their interface, together with the phase reactions occurring at high temperature and during subsequent cooling, resulted in development of a layered interaction zone where coexistence of a bcc solid solution phase with varying compositions, along with α-U, α-Zr and Mo2Zr phases could be noticed.

Diffusion Barrier Selection from Refractory Metals (Zr, Mo and Nb) Via Interdiffusion Investigation for U-Mo RERTR Fuel Alloy

U-Mo alloys are being developed as low enrichment monolithic fuel under the Reduced Enrichment for Research and Test Reactor (RERTR) program. Diffusional interactions between the U-Mo fuel alloy and Al-alloy cladding within the monolithic fuel plate construct necessitate incorporation of a barrier layer. Fundamentally, a diffusion barrier candidate must have good thermal conductivity, high melting point, minimal metallurgical interaction, and good irradiation performance. Refractory metals, Zr, Mo, and Nb are considered based on their physical properties, and the diffusion behavior must be carefully examined first with U-Mo fuel alloy. Solid-to-solid U-10 wt.%Mo versus Mo, Zr, or Nb diffusion couples were assembled and annealed at 600, 700, 800, 900 and 1000 °C for various times. The interdiffusion microstructures and chemical composition were examined via scanning electron microscopy and electron probe microanalysis, respectively. For all three systems, the growth rate of interdiffusion zone were calculated at 1000, 900 and 800 °C under the assumption of parabolic growth, and calculated for lower temperature of 700, 600 and 500 °C according to Arrhenius relationship. The growth rate was determined to be about 103 times slower for Zr, 105 times slower for Mo and 106 times slower for Nb, than the growth rates reported for the interaction between the U-Mo fuel alloy and pure Al or Al-Si cladding alloys. Zr, however was selected as the barrier metal due to a concern for thermo-mechanical behavior of UMo/Nb interface observed from diffusion couples, and for ductile-to-brittle transition of Mo near room temperature.

Effect of native oxide film on interaction between stainless steels and liquid Sn

The effect of native oxide films on the reaction of liquid Sn with stainless steels has been investigated by analysing the growth of intermetallic layers. The diversity of the oxide layers has been employed by exposure of various stainless steels [martensite stainless steel (MSS), austenite stainless steel (ASS) and duplex stainless steel (DSS)] in air for different times. Liquid tin was prone to metallurgically interact with MSS by formation of interfacial (Fe, Cr)Sn2 intermetallics. The native oxide film on MSS decreased (Fe, Cr)Sn2 layer thickness growth but cannot prevent the intermetallic formation. The reaction of Sn with ASS was hindered by the native oxide layer, and the thickness and coverage ratio of the (Fe, Cr)Sn2 intermetallics decreased with the increasing exposure time in air. The oxide film grown on DSS was stable enough to prevent the formation of (Fe, Cr)Sn2 and changed the tin from metallurgical interaction to physical attachment.