Metallographic Cross Sections Research Articles

Synchrotron EDXRD strain-temperature measurement during laser welding

Synchrotron EDXRD strain-temperature measurement during laser welding

Reaction Capsule Design for Interaction of Heavy Liquid Metal Coolant, Fuel Cladding, and Simulated JOG Phase at Accident Conditions

High temperature corrosion of fuel cladding material (15-15Ti) in high burn-up situations has been an important topic for molten metal-cooled Gen-IV reactors. The present study aims to investigate the simultaneous impact of liquid lead (coolant side) and cesium molybdate (fuel side) on the cladding tube material. A capsule was designed and built for experiments between 600 °C and 1000 °C. In order to simulate a cladding breach scenario, a notch design on the cladding tube was investigated pre- and postexposure. Material thinning by corrosion and leaching at temperatures ≥ 900 °C caused breaches at the notches after 168 h exposure. The temperature dependent cladding thinning phenomenon was used for kinetic interpretation. As the first of a two-part study, this paper will focus on the exposure capsule performance, including metallographic cross-section preparation and preliminary results on the interface chemistry.

Oxide scale microstructure and failure mechanism of alloy 601 under varying metal dusting conditions

Chemical plants which process highly carbonaceous gases at elevated temperatures are prone to catastrophic corrosion by metal dusting. Typically, commercial alloys with high amounts of protective oxide scale formers (Cr, Al, and Si) are used in these environments. However, scale failure is still frequently observed after an incubation time initiating pits. In this study, the microstructure and subsequent metal dusting-induced failure of the oxide scale on the commercial Ni-based alloy 601 was analyzed. Samples were exposed in different aggressive metal dusting gases and characterized using metallographic cross sections, electron beam microanalysis (EPMA), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and transmission electron microscopy (TEM). A thin and protective chromia scale formed in some regions with a continuous silica layer below. Across most of the alloy 601 surfaces, internal oxidation of Al could be linked to metallic particles in the outer scale. Additionally, MnCr2O4 was observed in the outer scale. Together with pores in the chromia, the spinel and metallic particles in the outer scale combined to provide pathways for carbon ingress. After exposure in a gas with a higher driving force for carbon deposition, a higher amount of carbon was incorporated in the growing oxide scale, resulting in earlier scale failure and metal dusting pit initiation.Graphical

Corrosion Behaviour of Ni-Based Alloys 230, 617 and 601 in CO2 Gas at 750 and 850°C

As a newly developed technology, oxyfuel combustion makes CO2 capture and sequestration feasible but raises a corrosion problem because of high concentrations of CO2 in flue gases at high temperatures. Conventional ferritic/martensitic heat resisting steels are sufficient to resist corrosion in oxygen or air but cannot survive in CO2-rich gases. To increase the process efficiency, higher temperatures will be used for energy production. As a result, austenitic steels and/or nickel-base alloys are required because of their superior corrosion resistance and mechanical properties at high temperature. This paper investigated the corrosion behavior of three nickel-based chromia-forming commercial alloys (230, 617 and 601) at 750°C and 850°C in a carbon dioxide environment for up to 500 h.Samples were cut to form 10mm x 8mm x (0.8-3) mm rectangular shaped coupons. After cutting, all surfaces of samples were ground up to 1200-grit finish, and further polished down to 3μm. Electro-polishing in 15% concentrated hydrochloric acid was used to remove the subsurface deformation zone. The grain sizes of 617 are larger (100-200μm) than those of 230 (20-80μm) alloy, and the 601 (10-30μm) alloy has the smallest grain size. All samples were ultrasonically cleaned with ethanol before being reacted in Ar-20%CO2 at 750℃ and 850°C, for up to 500 h. After reaction, samples were analysed by surface X-ray diffraction, metallographic cross-section analysis by optical microscopy, and scanning electron microscopy together with energy dispersive X-ray analysis.All three alloys showed good oxidation resistance by forming mainly a protective chromia layer with low weight changes. Internal Al2O3 was precipitated beneath a thin protective chromia layer for all cases. For 230 and 617 alloys, NiO and Cr-rich spinel outer layers were formed, but for 601 less iron and nickel outward diffusion was observed at both temperatures. Furthermore, some minor alloy elements (Mn, Ti, and Co) were also observed to diffuse into the chromia layers.Wagner’s Theory was applied to examine the critical chromium concentration for forming a protective chromia. This prediction indicated alloy concentrations were marginal for chromia formation at both temperatures for the test alloys. The observation of protective chromia formation can be attributed to the effect of other alloying elements, e.g. Al, Mn, Ti, Si etc. Because of the temperature effect on diffusion, the predicted result from Wagner’s Theory showed that the critical chromium concentration needed to form and maintain a protective chromia layer decreased with increasing the oxidation temperature, which is consistent with the experimental observation.The Al and Si oxides formed an additional protective barrier between the matrix and the chromia layer, preventing the diffusion of iron and nickel outwards and therefore increasing the oxidation resistance. Manganese effectively prevented carburization by combining with chromium oxide to form the outermost spinel oxide layer, increasing oxidation/carburisation resistance. Titanium diffused through the chromia layer, accelerating chromium diffusion and leading to higher kinetic rates. Tungsten reduced oxidation resistance by increasing the metal vacancies and therefore outward diffusion of Ni, Fe and Mn through the chromia scale.In general, no significant carbide formation was found in any of the Ni-base alloys in these reaction conditions. At 750℃, carburization due to CO2 reaction was found for 230 alloy but not for 617 and 601 alloys after 500h reaction. However, at 850°C, internal carbides from the reaction were observed for all three alloys. The variation in carburization extent among the different alloys can be attributed to the formation of oxides of aluminum, manganese and silicon, which can impede the inward diffusion of carbon, resulting in the reduction of carburizing kinetics.

Process development and process adaption guidelines for the deposition of thin-walled structures with IN718 using extreme high-speed directed energy deposition (EHLA3D)

Extreme high-speed directed energy deposition (EHLA) is a modified variant of the laser based directed energy deposition (DED-LB) and is being applied as an efficient coating process for rotational symmetric components. Characteristics of EHLA processes are feed rates of up to 200 m/min, which result in smaller weld bead deposition and thinner layer thicknesses compared to conventional DED-LB. When transferred to additive manufacturing, this characteristic utilizes the potential of depositing thin-walled filigree structures at deposition rates, which are comparable to typical DED-LB processes (EHLA3D). The results of this work were achieved with an EHLA3D machine, which is a modified CNC-type machine capable of operating feed rates with vf = 30 m/min. In this work, process parameters were developed for the deposition of thin-walled filigree structures with the Ni-based superalloy IN718. Single tracks with constant feed rates and a variation in the beam diameter and powder mass flow were deposited and analyzed regarding the resulting weld bead dimension and dilution zone. Then, process parameters were selected and transferred to the deposition of thin walls, and guidelines of the parameter adaption toward thin-walled deposition were defined. Two parameter sets were developed to assess the feasible wall-thicknesses deposited by EHLA3D. Depending on the developed parameter sets, wall thicknesses between 300 and 500 μm are achieved. To characterize the resulting thin-walls, surface roughness measurements and metallographic cross sections were conducted.

Reduction of the welding fume emission rate of gas-shielded cored wires by the MAG pulse welding process variant

The aim of the study is to reduce welding fume emissions from flux-cored wires using pulse technology. Low-alloyed cored wires of the rutile, basic, and metal powder types were selected for this purpose. The analyses were carried out on a DIN EN ISO 15011–1:2010 compliant test rig. In addition, high-speed recordings of the material transition mode and metallographic cross-sections were made to interpret the results. Using characteristic curves developed in pre-tests, the influence of pulse time, pulse frequency, and trigger current on the welding fume emission potential of the rutile cored wire was first determined. Short pulses, medium trigger current, and medium pulse frequency were found to have a positive influence on the emission rate.Finally, the welding fume emissions of the conventional characteristic are compared with the emission-optimized pulse characteristic. For all three filling types, emission reductions of up to 41% were found when using the pulse technology. When considering the ratio of fume generated to the mass of the weld metal produced, with the associated greatly reduced economy of the process, it became apparent that pulse welding is not suitable for welding cored wires without restrictions.In summary, the suitability of pulse GMAW technology for reducing welding fume emissions can also be confirmed for flux-cored wires.

Microscopic Characterization of Compound Layers

Abstract The properties of the compound layer have a significant influence on the lifetime of nitrided surface layers. In addition to a sufficient thickness, the compound layer characteristics include the phase composition and the porosity. Complex methods such as GD-OES or XRD are already used to qualitatively and quantitatively determine the phase composition of the compound layer. Particularly with regard to the characterization of the pore seam, no method has yet been identified that can be clearly recommended. In this work, the extent to which compound layers can already be characterized with the aid of microscopic examination methods is shown. For this purpose compound layers with varying thickness, phase composition and porosity were formed in the surface area of the material EN31CrMoV9 and EN42CrMo4 by different nitriding processes. It is demonstrated how the phase composition of compound layers can be studied qualitatively by means of special etchants on metallographic cross sections and subsequently quantitatively by image analysis. A more extensive characterization of the pore seam beyond the state of the art could be performed by scanning electron microscopy studies as well as 3D X-ray microscopy.

Three-dimensional annular heat source for the thermal simulation of coaxial laser metal deposition with wire

Coaxial laser metal deposition with wire (LMD-w) is an innovative additive manufacturing technology in which a wire is coaxially fed through the center of a hollow laser beam into a laser-induced melt pool. This special configuration results in a direction-independent process, which facilitates the manufacturing of thin-walled metal components at high deposition rates. However, laborious experimental test series must be conducted to adjust the process parameters so that the substrate and the part do not overheat. Therefore, models are needed to predict the resulting temperature field and melt pool dimensions efficiently. This paper proposes a finite element simulation model using an innovative heat source, which considers the unique intensity distribution of the annular laser spot. The heat source parameters were calibrated experimentally based on fusion lines obtained from metallographic cross sections of aluminum alloy samples (AA5078 wire and AA6082 substrate). Subsequently, the temperature distribution in the substrate plate was measured by means of thermocouples to validate the developed model. It was shown that the proposed heat source replicates the heat input accurately. With the presented model, essential features for process development, such as the temperature field and the melt pool dimensions, can be reliably predicted. The model contributes to a better understanding of the LMD-w process and facilitates an efficient process development in future research work as well as for industrial applications. Key words: thermal simulation, annular laser spot, heat source, laser metal deposition, coaxial wire feeding, directed energy deposition

Short-Time Creep Deformation of the Coarse-Grained Nickel-Base Alloy 247 and Its Implications on the High-Cycle Fatigue Behavior

Abstract Cast polycrystalline nickel-base superalloys are typically used for critical high temperature aerospace and automotive components, such as turbine blades or turbocharger wheels. These high temperature components can undergo creep damage caused by, e.g., centrifugal forces on the turbine rotor blades, as well as high-cycle fatigue (HCF) from, for instance, vibrations of the rotor blade. Therefore, both, creep resistance and fatigue strength are important mechanical properties of these materials. The study presented here addresses the introduction of creep damage and its influence on the high-cycle fatigue behavior. For this purpose, fatigue specimens of coarse-grained Alloy 247 LC CC blade root material were prestressed on a pneumatic creep test rig to achieve creep-induced microstructural damage. The isothermal 900 °C short-time creep investigations below 1000 h test duration were performed at different tensile stresses which result in different strain rates. After the creep tests, scanning electron- and optical microscopy investigations of metallographic cross section of selected specimens were performed to determine the creep-induced grain boundary damage such as pore count, pore size, and coarsening of the γ' structure. This was followed by uniaxial, stress-controlled isothermal 850 °C high cycle fatigue tests on undamaged and predamaged specimens at a frequency of 10 Hz and a load ratio of R = −1. Subsequently, fractographic and cross section investigations, which provide information on the fatigue cracking, the failure initiating defects, and the pore morphology, were performed. The results of this study show that the degree of creep induced porosity is a dominant structural parameter for the HCF behavior of the investigated nickel-base superalloy.

Laser welding of different pure copper materials under consideration of shielding gas influence and impact on quality relevant surface topographical features

The high demand for electronic products increases the need for high-quality welds of copper. Laser welding can be applied but may result in undesired weld characteristics such as humping or spatter. Process control is needed to identify defective welds in the production line. Surface topographical features can be used to identify different weld characteristics by optical coherence tomography (OCT). The resulting surface topography of a weld can be influenced by process parameters like its material properties or the application of process gas. In this work, we investigate the influence of different pure copper materials and process gas on weld seam surface features for the classification of quality-relevant weld characteristics. First, the resulting changes in weld depth and metallographic cross sections are qualitatively and quantitively characterized for different pure copper materials under the consideration of weld categories such as melt ejection, deep penetration welding, humping, and heat conduction welding with and without the application of shielding gas. Afterward, a qualitative and quantitative analysis of weld surface features is performed for the beforementioned categories under consideration of the copper material and shielding gas. As a result, an influence on the achievable weld depth could be identified for pure copper with residual phosphor content. No significant changes in surface topographical features could be identified for different material properties of copper. The influence of shielding gas and pure copper material is found to be negligible on surface topographical characteristics for process control.

Combining 2D and 3D Characterization Techniques for Determining Effects of HIP Rejuvenation After Fatigue Testing of SX Microstructures

A hot isostatic pressing rejuvenation heat treatment is applied to a CMSX-4 type SX superalloy after it has been subjected to a low-cycle fatigue test to rupture. The evolution of microstructural defects, such as pores and cracks which are present after fatigue, has been tracked in 3D by X-ray tomography before and after rejuvenation. From the rejuvenated specimen, series of metallographic cross sections were prepared and investigated by scanning electron microscopy for getting complementary 2D information at high resolution. The micrographs were stitched to a panorama which was then matched into the 3D representation of the specimen volume. By combining 3D and 2D data, statistical volume-related quantities were achieved, while detailed characteristics have been assigned to individual defects present in the 2D panorama micrograph. This technique is in general appropriate for length-scale bridging microstructural investigations. Results of the performed investigations concerning the rejuvenation effect on the microstructure are presented and discussed.

A study on non-destructive testing of geometrical parameters of self-piercing riveting joints using an acoustic microscope with a scanning focusing converter

ABSTRACT A non-destructive technique was proposed for geometrical parameters’ measurement of self-piercing riveting (SPR) joints based on ultrasonic C-scan image. Firstly, in order to enhance the detection precision, the characteristics of the ultrasonic echo signal at the edge of internal structure were analysed, and a theoretical formula on its sound intensity distribution was established. Then, an image segmentation process for the detection of SPR expansion diameter was suggested. Results showed that taking the greyscale value at the ‘inflection point’ from the C-scan image as the threshold of the segmentation, the non-destructive test results can get good correlation with the metallographic cross section, which provides a new method on the quality evaluation of SPR by using non-destructive test.

Understanding the effects of temporal waveform modulation of laser emission power in laser powder bed fusion: Part II - Experimental investigation

The laser powder bed fusion (LPBF) process has historically been operated with high-brilliance fibre laser sources with continuous wave (CW) emission. Nonetheless, temporal waveform modulation of the laser emission power at high-frequency levels can provide a means to enhance the deposition process by modifying the melt dynamics and solidification mechanisms. In order to disclose the effect of different waveform shapes and their parameters, an experimental study using an open LPBF system was conducted. This paper is the second part of an investigation on this topic, which aims to validate the analytical model proposed in the first part of the work. The LPBF system that was developed enabled the power emission profiles to be programmed during single-track depositions. Four different waveform shapes were tested (namely square wave, ramp up, ramp down and triangle wave) at different levels of waveform amplitude (ΔP= 200–400 W) and different frequencies (fw = 2–4–6–8 kHz) during the single-track deposition of stainless steel AISI316L. High-speed imaging acquisitions allowed the melt dynamics to be disclosed and the melt-oscillation frequency to be identified. Larger waveform amplitudes and waveforms with sudden variations of emission power generated melt ejections and process instabilities. Stable conditions could be identified when employing ramp up and triangle waveforms with ΔP = 200. Melt-surface oscillation frequency corresponded to the values imposed via the modulation of the laser emission power, thus validating the analytical model of Part I, which correlated the melt-surface temperature to the recoil pressure induced over the molten pool. Optical microscopy images and metallographic cross-sections confirmed the high-speed video observations. Three-dimensional reconstructions of the depositions via focus variation microscopy allowed the build rates and roughness of the single tracks to be determined. Build rates obtained in stable deposition conditions with waveform modulation are analogous to values obtainable with CW emission, and beneficial effects over the roughness were reported.

Electrodeposition of Ni-W Alloy from Citric Acid Free Aqueous Electrolyte As a Substitute for Hard Chrome Coating and the Effect of Tungsten Content on Coating Hardness

In the industry, chrome coating is an important player in the functional layer application. Due to its high corrosion and wear resistance as well as high hardness [1], hard chrome plating is a popular choice in the automotive and aerospace industry. However, since September 2017, the application of chrome (VI) in surface treatment is banned by the European Chemical Agency (ECHA) due to chrome (VI) being toxic and environmentally hazardous [2]. Chrome (III) compound is a popular substitute for chrome (VI) due to it being less toxic compared to chrome (VI). However, chrome (III) coating has a lower corrosion resistance, and the electroplating process is more sensitive to metallic impurities.Many new innovations have since been developed such as the plasma electrolytic oxidation (PEO), extreme highspeed laser deposition (EHLA). Even established technologies such as physical vapour deposition (PVD), thermal spraying and case hardening process have tried to replace hard chrome coating with a degree of success. Admittedly, the above-mentioned technologies have their fair share of disadvantages. PEO, a green procedure [3], causes a metal substrate to develop a highly resistant oxide which is extremely strong and corrosion as well as wear resistant. The process however needs a high temperature and pressure, continuous replacement of electrolytes and consumes a great amount of power which made the process not feasible for a wide industrial application [4-6]. EHLA and thermal spraying on the other hand are restricted to rotational symmetric components. PVD is restricted to substrates that can handle high processing temperature like nitrable ferrous base materials. Lastly, case hardening processes requires long heat treatments which contribute to a higher process cost. [7]In our presentation, another alternative for chrome coating based on electrodeposition will be introduced. The element tungsten is considered in our experiments because tungsten not only has an excellent corrosion properties and high tensile strength at high temperature, but it also has a microhardness of 650 Vickers. However, it is not possible to deposit tungsten from an aqueous solution because tungstate cannot be directly reduced to metallic tungsten due to a very low overvoltage for hydrogen evolution on tungsten. Thus, an induced co-deposition mechanism is needed, and it is known that tungsten can be easily codeposited with iron group metal. [8-9]In this study a modified Watt’s bath is used as electrolyte to deposit NiW alloy. Our preliminary tests have shown that tungsten can also be deposited with nickel without the help of citric acid as complexing agent. The usage of citric acid does indeed inhibit the deposition of nickel but show no influence in the deposition of tungsten. Hence, in our study, experiments with the rotating disc electrode (RDE) will be done to see if tungsten content in the coating could be increased when the hydrodynamic and coating parameters are manipulated. The chemical composition of the layer is measured using SEM/EDX and the surface morphology is pictured using SEM. Metallographic cross-sections are made to see if there are any fissures in the layer and the hardness of the layer is measured using the microhardness test. The dependency of hardness on the tungsten content in the layer and the annealing parameter will also be shown in the presentation. XRD measurement is conducted for phase analysis and grain size calculation. Figure 1

Investigations on the effect of standing ultrasonic waves on the microstructure and hardness of laser beam welded butt joints of stainless steel and nickel base alloy

Joining dissimilar metals with superior quality is important to provide tailored, lightweight, and cost-efficient components. Expensive and durable materials are exceptionally used where the cheaper material would not withstand the requirements. With laser beam welding, dissimilar metals can already be joined with high precision, low heat input, and a customizable mixing degree. Introducing ultrasonic excitation into the weld pool is a promising approach for further improvements like customizing the solidification morphology and avoiding weld defects. The experiments are carried out with round bars of 30 mm diameter made of 1.4301 steel alloy and 2.4856 nickel base alloy. Ultrasonic-assisted laser beam butt welding is conducted on rotating specimens with a laser beam power of 7.75 kW and a welding speed of 0.95 m/min. The specimens are evaluated by metallographic cross sections, hardness measurements, and energy-dispersive x-ray spectroscopy (EDX). The ultrasound is used to excite an eigenmode of the sample and the weld position is varied at stress- and displacement-nodes. Two different mechanisms of acoustic grain refinement are revealed. Heterogeneous nucleation is fostered in weld seams that are positioned in stress-nodes, and the fragmentation of dendrites is fostered in displacement-nodes. The welds' chemical compositions correspond to the change of solidification morphology.

Investigations on the Specifics of Laser Power Modulation in Laser Beam Welding of Round Bars

Welding round bars of large diameters in a rotational laser beam welding process corresponds with weld pool bulging and the risk of weld defects. Power modulation is a promising approach for bulge reduction and for keyhole stabilisation to achieve superior weld quality. The following investigations are about the specific effects of power modulation for round bars with a diameter of 30 mm. The welding speed is 0.95 m/min and argon is used as shielding and process gas. Triangle shaped power modulation at 8 kW average laser beam power, 0/2/4/6 kW amplitude power and 2/10/50 Hz modulation frequency is used for the round bar welding of a 1.4301 steel alloy. The welds are evaluated by visual inspection, metallographic cross sections and scanning acoustic microscopy. The amount of weld defects increases at medium and high power modulation, but weld pool bulging is already reduced at low power modulation. Weld pool bulging can be impeded by a low normalised power modulation frequency of 0.05 and a high modulation depth of 0.86. The power modulation’s advantages of weld mixing and degassing do not apply to rotational round bar welding because of the linear welding speed’s gradient from the specimen surface to the centre.

Laser Preheating for Hot Crack Reduction in Direct Metal Deposition of Inconel 738LC

Welding of precipitation-hardenable nickel-based super alloys that contain large amounts of Al and Ti is challenging due to their high susceptibility to hot cracking. For metal additive manufacturing (AM) by powder bed fusion (PBF) or direct metal deposition (DMD), various welding process adjustments may prevent the formation of cracks. The aim of this study is the development and experimental characterization of a laser preheating process for DMD of Inconel 738LC. Metallographic cross-sections of multiple test specimens were analyzed to quantify the effect of initial substrate temperature, specimen geometry, deposition parameters, and scanning strategy on the resulting crack density. The results show that increased substrate temperature by laser preheating and reduced specimen size leads to crack-free deposited structures. Therefore, the proposed preheating process may be applied for part fabrication or repair by DMD to reduce or even completely prevent the risk of hot cracking.

Effect of Hydrogen on the Internal Oxidation of a Pd–Cr Alloy in Dual-Atmosphere Conditions

The effect of hydrogen on oxygen permeability has been studied in a diluted Pd–Cr alloy in dual- and single- atmosphere conditions between 600 and 950 °C. The 0.3 mm thick Pd–1.5Cr foil was exposed in dry and humid air as well as in dual-atmosphere conditions, with one sample surface being exposed to air and one to hydrogen, as encountered in solid oxide fuel cells. At all temperatures, Cr oxidized internally forming internal oxidation zones which were measured in metallographic cross sections. Below 800 °C, an external layer of PdO formed on the surface decreasing the internal oxidation kinetics. No measurable effect of hydrogen on the internal oxidation of Cr in Pd has been detected.

Electron Beam Powder Bed Fusion of Water Atomized Iron and Powder Blends.

In the present state of the art, highly spherical alloy powders are employed as feedstock in powder bed fusion processes. These powders are characterized by high flowability and apparent density. Their elaborate fabrication process is reflected in high powder price, adding a significant fraction to the cost of additively manufactured parts. Thus, the use of non-spherical powders, such as water atomized material, can lower costs significantly. Here, the electron beam powder bed fusion (PBF-EB) of standard water atomized iron powder used for press-and-sinter is studied. Despite raking problems, using the coating mechanism in standard configuration samples with densities exceeding 99% were fabricated. In a further step, the addition of alloying elements by powder blending is explored. Important powder properties of feedstock blended from irregular and spherical powders are characterized. The PBF-EB processing of two alloys is presented. The first represents a low carbon steel. Samples were characterized by metallographic cross-section, energy dispersive X-ray (EDX) mapping, and mechanical testing. The second alloy system is a FeCrAl. After PBF-EB processing of the powder mixture, chemical homogeneity was achieved. Besides the low cost, this approach of using water atomized powder mixed with master alloy offers the advantage of high flexibility for potential application.

Effect of the Biodegradable Component Addition to the Molding Sand on the Microstructure and Properties of Ductile Iron Castings.

In this work, the results of the examinations of the effect of the mold material and mold technology on the microstructure and properties of the casts parts of ductile cast iron have been presented. Four different self-hardening molding sands based on fresh silica sand from Grudzen Las, with organic binders (no-bake process), were used to prepare molds for tested castings. A novelty is the use of molding sand with a two-component binder: furfuryl resin-polycaprolactone PCL biomaterial. The molds were poured with ductile iron according to standard PN-EN 1563:2018-10. The microstructure of the experimental castings was examined on metallographic cross-sections with PN-EN ISO 945-1:2019-09 standard. Observations were made in the area at the casting/mold boundary and in a zone approximately 10 mm from the surface of the casting with a light microscope. The tensile test at room temperature was conducted according to standard PN-EN ISO 6892-1:2016-09. Circular cross-section test pieces, machined from samples taken from castings, were used. In the present experiment, it was stated that interactions between the mold material of different compositions and liquid cast iron at the stage of casting solidification led to some evolution of casting’s microstructure in the superficial layer, such as a pearlite rim observed for acidic mold sand, a ferritic rim for alkaline sand, and graphite spheroids degeneration, especially spectacular for the acidic mold with polycaprolactone (PCL) addition. These microstructural effects may point to the interference of the direct chemical interactions between liquid alloy and the components released from the mold sand, such as sulfur and oxygen. Particularly noteworthy is the observation that the use of molding sand with furfuryl resin with the addition of biodegradable PCL material does not lead to an unfavorable modification of the mechanical properties in the casting. The samples taken from Casting No. 2, made on the acidic molding sand with the participation of biodegradable material, had an average strength of 672 MPa, the highest average strength UTS-among all tested molding sands. However, the elongation after fracture was 48% lower compared to the reference samples from Casting No. 1 from the sand without the addition of PCL.