Compressive Rheological Behavior and Microstructure Evolution of a Semi-Solid CuSn10P1 Alloy at Medium Temperature and Low Strain

Copper–tin alloys are widely used in the machining and molding of sleeves, bearings, bearing housings, gears, etc. They are a material used in heavy-duty, high-speed and high-temperature situations and subject to strong friction conditions due to their high strength, high modulus of elasticity, low coefficient of friction and good wear and corrosion resistance. Although copper–tin alloys are excellent materials, a higher performance of mechanical parts is required under extreme operating conditions. Plastic deformation is an effective way to improve the overall performance of a workpiece. In this study, medium-temperature compression tests were performed on a semi-solid CuSn10P1 alloy using a Gleeble 1500D testing machine at different temperatures (350−440 °C) and strain rates (0.1−10 s−1) to obtain its medium-temperature deformation characteristics. The experimental results show that the filamentary deformation marks appearing during the deformation are not single twins or slip lines, but a mixture of dislocations, stacking faults and twins. Within the experimental parameters, the filamentary deformation marks increase with increasing strain and decrease with increasing temperature. Twinning subdivides the grains into lamellar sheets, and dislocation aggregates are found near the twinning boundaries. The results of this study are expected to make a theoretical contribution to the forming of copper–tin alloys in post-processing processes such as rolling and forging.

Study on the High-Temperature Deformation and Dynamic Recrystallization Behavior near the Interface of Stainless Steel Cladding

To ensure the long service life of concrete buildings in the marine environment, it is urgent to develop building materials with good corrosion resistance and weatherability. Stainless steel cladding is suitable for a highly corrosive environment and provides cost advantages. This paper investigated the deformation coordination and the microstructure evolution near the cladding interface of stainless steel/carbon steel. The stress-strain curves at different temperatures and strain rates were analyzed on the basis of high-temperature compression experiments. In addition, the sin-hyperbolic constitutive model was constructed, and the optimized parameters were obtained using electron backscatter diffraction characterization technology. The results show that at the deformation temperature of 1100 °C and the strain rate of 1 s−1, the deformation coordination increases significantly near the interface, accompanied by a large number of recrystallized grains, which has a positive impact on the comprehensive performance of the materials.

Modeling Hot Deformation of 5005 Aluminum Alloy through Locally Constrained Regression Models with Logarithmic Transformations

This study presents the adoption of locally constrained regression models (LCRMs) with logarithmic transformations in order to model the flow stress behavior of the high-temperature deformation of 5005 aluminum alloy. Hot tensile tests for 5005 aluminum alloy were conducted under the temperatures of 290 °C, 360 °C, 430 °C, and 500 °C, and the strain rates of 0.0003/s, 0.003/s, and 0.03/s. The flow stress behavior was analyzed based on variations in temperature and strain rate. The flow stress during the hot deformation was modeled using the traditional Arrhenius type constitutive equation and the neural network approach. Then, for improved prediction accuracy, the flow stress was modeled using LCRMs. The prediction accuracies of the models were compared by calculating the MAE (Maximum Absolute Error) and RMSE (Root-Mean-Squared Errors) values. The MAE and RMSE of the LCRMs were lower than the errors of the Arrhenius equation and the neural network model. The results show that LCRMs can be useful in modeling the flow stress of 5005 aluminum alloy, and that the developed model can accurately predict the flow stress.

Increasing the wear resistance of the pump-controlled hydraulic drive units

Due to the lack of 63.5 mm balloons in Ukraine in the first layout of Hop-900 hydraulic transmission sample, the balls of the PBG company (Precision Ball and Gauge Co., England) were used. However, the trials of hydraulic transmission showed increased wear and cracks on the surface of the balls. Goal. The purpose of the work is to increase the wear resistance of the units of a pump-controlled hydraulic drive. Methodology. The coating on the TICRN ball was carried out at the Bu-Lat-3T installation. The coating modes were chosen using a methodology for mathematical planning of an experiment by evaluating microhardness of molded coating and the material use factor. Metallographic studies of the structure of the materials studied and sprayed coatings were performed on the digestive and non-digestive grinds on the MIM-8M microscope. The phase composition of the spray coatings was determined on a Don-1.5 diffractometer in monochromatic CUKα radiation. Results. Following the wear resistance of all investigated materials showed the largest wear resistance of the balls with ion-plasma coating on the surface. Originality. The tests of the samples of radial ball-piston hydraulic transmission of GOP-900 type allowed to conclude that their reliability and further improvement is largely due to the reliability of the piston ball, to which there are high requirements for wear resistance, minimum volume of force and temperature deformation. Practical value. Taking into account the negative experience of using imported steel balls from chrome steel, positive experience of using balloons from Steel SH-15CG, mastered by the production of OJSC HARP, and at the same time, the need to increase the heat resistance and wear resistance of balls should be considered as promising research when using beads from powder, rapid steels of type P6M5F3-MP, ceramic balls having high strength properties.