To investigate the effects of deformation parameters on the phase transformation of B1500HS high-strength steel, non-isothermal deformation tests were conducted on a Thermomaster-Z thermal mechanical simulator under different conditions in this study. Qualitative and quantitative investigations were carried out by analyzing the dilatation curves, color metallograph, and hardness data of deformed specimens. The results indicate that deformation can promote the formation of non-martensite. Higher initial deformation temperature and lower strain are beneficial for obtaining more martensite in the deformed high-strength steel and leading to higher martensite transformation temperatures. Meanwhile, the variation of strain rate has relatively small effects on the content and transformation temperature of martensite, and the effects do not show a singular trend.

Fracture is a common and fatal defect in the hot stamping of aluminum alloys. Accurate prediction of high-temperature fracture behavior is crucial for forming process planning. However, existing high-temperature fracture criteria suffer from a trade-off between predictive capability and parameter calibration difficulty, which limits their industrial application. This study establishes a high-temperature semi-coupled damage model by incorporating strain rate and temperature terms into a semi-coupled fracture framework and coupling it with a viscoplastic constitutive model. This model maintains the convenience of parameter calibration while describing the nonlinear characteristics of damage evolution using a hyperbolic sine function. The model was applied to the finite element analysis of 7075 aluminum alloy. For hot tensile tests, the simulated load–displacement responses, fracture displacements, and strain fields agree with the experiments, with a maximum load–displacement root mean square error (RMSE) of 0.047 kN and a maximum fracture displacement relative error of 3.141%. For isothermal bulging validation tests, the average relative error for fracture location prediction is 5.10%, and the maximum relative error for normalized thickness is 6.67%. These results demonstrate that within 350–450 °C and 0.001–0.1 s⁻¹, the proposed model accurately predicts the damage initiation, evolution, and fracture behavior.

The torsional behavior of an extruded AZ31 magnesium alloy was investigated by combined axial-torsion mechanical testing with different stress ratios. The SEM-EBSD was used to analyze the microstructure and texture evolution of deformed samples. The results indicate that the axial tension results in a concave-down shape of shear stress–strain curves, while a concave-up shape after yielding is presented during combined compression-torsion loading due to twinning mechanism. Compared to pure shear, the yield strength decreases by 7 MPa and shear strain increases by 1% under σ:τ = −1:1 with same shear stress. Due to the Swift effect, a strain partitioning is displayed for axial strain during combined tension-torsion loading with low stress ratio. The twin volume fraction is 90% under σ:τ = −1:1, and the local dislocation density with a KAM value of 1.1 is maximum under σ:τ = 2:1. The primary twin type is {10-12} twins with axial compression. The main deformation mode changes from basal slip to prismatic slip with increase in axial tension stress. Both basal slip and twinning are activated and the interaction between dislocation slip and twinning contributes to the complex strain hardening behavior during combined compression-torsion loading.

In this paper, TiAl-Nb sheets were fabricated via elemental foil metallurgy using Ti, Al, and Nb foils. The microstructure of the TiAl-Nb sheet was regulated by a two-step heat treatment process, which involved short-time holding at 1410 °C, 1430 °C and 1450 °C, followed by long-time holding at 1150 °C. Subsequently, the microstructure of the sheet was analyzed, emphasizing the orientation relationship and interface structure between the B2/β phase, Ti₃Al phase, and the TiAl matrix. The results indicated that, subsequent to diverse heat treatment processes, the TiAl-Nb sheet comprised α₂(Ti₃Al) and B2/β phases at the grain boundaries and within the grains, whereas the matrix structure was γ(TiAl). After TiAl-Nb sheets were heat-treated at 1410 °C for 3 min and then at 1150 °C for 2 h, the microstructure of the sheets was observed to be composed of relatively fine lamellar structures. The TiAl phase, Ti₃Al phase and B2/β phase existed in the form of coherent interfaces with extremely small misfit degrees. The interfacial energy between phases was small, making it easier to obtain an alloy microstructure with a higher content of the γ(TiAl) phase. To further provide a basis for the selection of heat treatment processes, the matrix method analysis indicated that, after holding at 1410 °C for 3 min and subsequently at 1150 °C for 2 h, the TiAl phase and Ti₃Al phase in the sheet structure exhibited obvious preferred orientations. A short β-phase holding (3 min) followed by a long α + γ two-phase holding was an effective process route for obtaining a fine lamellar structure.

Owing to the low stiffness of thin-walled workpieces, disturbances can readily arise during milling, severely compromising machining accuracy and surface quality. This study proposes a new viscoelastic model of a magnetorheological elastomer (MRE) and analyzes its vibration reduction performance under dynamic cutting forces. First, the governing equations of the system are derived from Newton’s second law, and the amplitude-frequency response curves are obtained using the harmonic balance method. The analytical results are then validated by Runge–Kutta numerical integration, with good agreement between the two approaches. Next, the vibration reduction performance of the MRE-based viscoelastic nonlinear energy sink (MNES) and the effects of its parameters are analyzed. Finally, the nonlinear stiffness coefficient and damping ratio are varied simultaneously at different mass ratios to identify the optimal parameter ranges for the MRE-based viscoelastic nonlinear energy sink of magnetorheological elastomer. The results show that the maximum amplitude of the main system first decreases and then increases as the nonlinear stiffness increases. With appropriate parameter selection, the MRE-based viscoelastic nonlinear energy sink of magnetorheological elastomer provides better vibration reduction performance than the traditional nonlinear energy sink. In addition, as the mass ratio increases, the minimum attainable value of the main-system amplitude initially decreases and then approaches a constant, while the optimal ranges of the nonlinear stiffness coefficient and damping ratio widen slightly. By combining a set of calculated parameters with the differential constitutive equation of the magnetorheological elastomer, the corresponding stress–strain curve is obtained. This provides guidance for the fabrication of magnetorheological elastomers with favorable vibration-damping performance. The stability of milling chatter is also analyzed. The calculated stability lobe diagram and supplementary time-domain verification results show that a milling system with the MNES can effectively suppress chatter and allow a greater depth of cut.