Archives of Foundry Engineering

One of the major limitations of using molten salts for CO2 capture processes from industrial gas streams is the availability of construction materials with adequate corrosion resistance. This is due to the high operating temperature of the process and the aggressive environment of chloride-fluoride molten salts. In this study, the influence of temperature and a molten, eutectic mixture of CaCl2 - CaF2 with the addition of 10 wt.% CaO on the behavior of SS316 steel was evaluated. Tests were conducted at 700 °C and 950 °C for 40, 80, and 120 hours. Material samples were weighed before and after the tests, and selected samples underwent microscopic analysis (SEM, EDS), measurements of the corrosion product layer thickness, and wall thickness. The corrosion rate of SS316 steel was also determined. The results showed, among other findings, that at 700 °C, mass losses were minimal (max. 0.5%), and the corrosion layer had an average thickness not exceeding 8.2 μm. At 950 °C, mass loss increased to 3.85%, and the corrosion product layer reached an average thickness of 83 μm. Intergranular corrosion was also observed, along with enrichment of the corrosion layer with salt elements (Ca, O, Cl) and steel alloying elements (Cr, Ni). Additionally, segregation of Cr, Mn, and Mo was noted at grain boundaries. The calculated corrosion rate of SS316 steel at 700 °C was 171 μm/year, while at 950 °C, it was significantly higher at 1540 μm/year.

Aluminium-silicon alloys are widely used in industrial practice due to their many advantages, including light weight and relatively high strength. The consumption of these light engineering materials is constantly increasing, especially in the automotive industry, due to new greenhouse gas (GHG) emission standards. The sustainable development strategy in the foundry industry is related to reducing the amount of waste and pollution generated during the production process. In turn, reducing the number of production shortages and waste requires the production of good quality Al-Si castings, and thus the appropriate selection and monitoring of technological parameters affecting the quality of the liquid alloy, including the level of purity and the degree of its gasification. The main objective of the research conducted to evaluate the technological properties of the AlSi12CuNiMg (AlSi12) alloy was to identify the causes of increased defect rates in piston castings during the production process at the Złotecki Sp. z o.o. The tests were carried out using two Al-Si alloys with silicon content close to eutectic (approx. 12%) used for piston castings, from two different suppliers. Three measurement methods were used to evaluate the technological properties of the tested AlSi12 alloys: thermal analysis, fluidity test and density index for gasification measurement. Based on the analysis of the results, it was concluded that an excessively low-density index level might be the cause of the increased casting defect rates observed in the production of pistons for internal combustion engines and compressors, particularly for castings with significant variations in wall thickness.

The aim of this study was to determine the hardness of vermicular cast iron subjected to austempering, depending on the parameters of the heat treatment process. The heat treatment was conducted based on orthogonal experimental design, with a total of 27 experiments performed. The samples underwent austenitization at temperatures of 890°C, 925°C, and 960°C, followed by austempering at 290°C, 340°C, and 390°C. The austenitization and austempering times were set to 90 min, 120 min, and 150 min. To analyse the influence of these parameters, a full polynomial regression model was developed. The proposed model, which describes the hardness of the cast iron after heat treatment, showed a predicted coefficient of determination (R²) of approximately 78%. For optimization purposes, the Response Surface Methodology (RSM) was employed. The results of the ANOVA analysis indicated that the austempering temperature (Tpi), the square of the austenitization time (τγ²), the interaction between austenitization temperature and time (Tγ τγ), as well as the interaction between austenitization and austempering temperatures (Tγ Tpi) had the most significant impact on the examined parameter. Following variance analysis, the model was refined once more to eliminate insignificant predictors. The simplified model improved the predicted coefficient of determination to 93%. The optimal conditions for the analyzed parameters, assuming a maximum hardness of approximately 440 HB, were obtained under the following heat treatment conditions: Tγ = 930°C, Tpi = 290°C, τγ = 150 min, and τpi = 150 min.

The greatest influence on the wear of tool steel has its microstructure, which depends on the chemical composition and heat treatment. The presence of carbides in the alloy matrix is not always desirable and can have an adverse effect on the wear mechanism of this material, resulting in the formation of stresses and even cracks during operation. Therefore, it is necessary to apply heat treatment, which makes the microstructure homogeneous or allows for the precipitation of secondary carbides strengthening the matrix. The main aim of this study is to examine the effect of molybdenum addition on the structure and microhardness of high-manganese cast steel in the as-cast state and after heat treatment. The as-cast microstructure consists of a high-manganese austenitic matrix with molybdenum carbides and alloy ledeburite distributed at grain boundaries. As a result of solution heat treatment, only the alloy ledeburite is dissolved. The result of aging is not the precipitation of secondary molybdenum carbides but of alloy cementite. Raising the temperature or extending the time of solution heat treatment changes the hardness of austenite to a very small degree only, and the decrease in hardness becomes less significant with the increasing addition of molybdenum. Extending the tempering time has a similar effect, and changes in the hardness decrease are less pronounced.