Dynamic corrosion mechanical properties of magnesium alloys with Erbium in the chloride ions environment

The X-ray diffraction (XRD), scanning electron microscope (SEM), weight loss corrosion rate, corrosion residual strength (CRS), and slow strain rate tensile (SSRT) methods were used to study the effects of the addition of rare earth Erbium (Er) on the dynamic corrosion mechanical properties of the AM50 magnesium alloy. The results show that after Er was added, a new phase of Al3Er appeared and the microstructure was refined. The corrosion resistance of rare earth Er addition to the alloy was 0.5% > 1.5% > 1.0% > 0. Furthermore, the corrosion rates decreased in 432 h. The CRS results within 168 h show that the strength after an addition of 0.5% Er was the highest and the decline rate was the smallest. According to the shape of the tensile curve of CRS and the morphology of the tensile fracture, the addition of rare earth Er did not change the fracture form of the alloy, which remained as quasi-cleavage.

Mechanical Characterization of Porcine Skin Starting Material

Porcine skin has been used as a starting material in several released mesh medical devices. Although this controlled animal derived material is prevalent in tissue engineered medical devices, little is known about its mechanical properties. This study mechanically characterized Porcine Skin Starting Material (PSSM), provided by Midwest Research Swine. Uniaxial tensile tests were performed on samples cut from different regions (back and neck) and orientations (parallel and perpendicular to the spine) on the PSSM. The stress-stretch relationship was determined for each sample utilizing a load frame equipped with a Digital Image Correlation measurement system. The PSSM skin demonstrates the classic nonlinear and linear regions seen in other biologic tissues. A bilinear curve fit method was used to separate the nonlinear and linear regions of the tensile curve, and each region was analyzed with an Ogden and linear model respectively. The results show that the tensile curve is better described with this method as opposed to analyzing the full curve with one model. A comparison was made between samples cut from the different regions and orientations. There were significant differences between the failure measures and mechanical indices from the two regions, and on average the back behaved anisotropically and the neck isotropically. The PSSM mechanical properties from this study could serve as a preliminary guide for those exploring devices or processes in the tissue engineering field. The methods demonstrated in this study could also help characterize other biologic materials, and be used towards the development of tissue specific industrial standards.

Cyclic Ramberg-Osgood Parameters of 316SS Weld Metal Under In-Air and PWR-Water Environments

At present the available Ramberg-Osgood (R-O) parameters for different metals (e.g. in ASME code and other literature) are static (generally based on a tensile curve). These static R-O parameters cannot accurately model the cyclic plasticity behavior. This work presents the cyclic R-O material hardening parameters for 316 stainless steel similar metal welds. The parameters were estimated under various conditions (in-air at room temperature, 300°C in-air, and in-air at primary water conditions for a pressurized water reactor (PWR)). It is anticipated that the reported results would be useful for computational mechanics based shakedown analysis and fatigue life estimation of PWR components.

Predicting Flow Curves of Q&P Steel Using Sharp Pyramidal Nanoindentation on Constituent Phases: Isostrain Method

In this research, a method is presented for predicting macroscopic plastic flow behavior of a quench and partitioning (Q&P) steel using data of nanoindentation experiments.The method is based on Tabor’s model in which nanohardness values obtained with indenters of different angles to be connected to the flow behavior of the indented material. The process consists of two steps: (i) the macroscopic flow relation of each microphases assessed based on the characteristic strain and constraint factor, (ii) the total flow curve of the steel extracted through an isostrain manner. A rationally successful prediction of the macroscopic plastic flow of the Q&P steel is obtained from the constituent phases properties due to consideration of the indentation size effect and application of a rule of-mixture. Eventually, the accuracy of the estimation is verified by comparing the predicted stress-strain curve to the tensile curve obtained from a standard bulk sample.

Mechanically robust and highly stretchable woven fabric containing metal wire for personal protective clothing

Highly stretchable composite yarns containing metal wire have attracted great interest as a fundamental building block for special protective fields. A method for producing tri-component elastic-conductive composite yarns (t-ECCYs) has been described previously. The main purpose of this work was to investigate the mechanical behavior and structural stability of a highly stretchable woven fabric containing t-ECCYs inserted in its weft direction. By virtue of the unique structure of t-ECCYs, the woven fabric has a denser and tighter surface than the reference fabric (100% cotton), which facilitates its weft elastic stretchability in excess of 40%. Furthermore, a typical initial low-stress tensile curve characteristic and an acceptable cyclic elastic recovery stability at a higher strain of 25% were observed, indicating excellent mechanical robustness of as-prepared woven fabric. Also, a modified standard solid model by introducing an exponent to the exponential function can fairly well replicate the tensile characteristics during stretch. Importantly, the structural stability of the fabric remained nearly unchanged following cyclic expansion (≈43%) and washing-drying (10 times) cycles. It is promising that this kind of mechanically robust and highly stretchable woven fabric containing metal wire is prerequisite for the next wave of superelastic electromagnetic shielding materials.

Equal Load-Carrying Design of Lapped Joints of Al–Cu Dissimilar Materials

In order to avoid the adverse effects of additional moment and stress concentration of traditional lap joints, a new lap joint was put forward, according to the concept of “equal load-carrying”. Through static analysis and brazing characteristics consideration, the equal load-carrying design method of Al–Cu lap joint based on brazing method was established. Through three types of brazing, the relationship among two fracture modes, brazing process and static tension curve of lap joint, was analyzed. The results demonstrated that the selection of solder was required to simultaneously meet the requirements of brazability and mechanical properties. A certain relationship existed between the fracture mode of the lap joint and the static tensile curve, while the segments of the static tensile curve corresponded to the fracture paths of the two fracture modes. When the brazing holding time was quite short, the interface bonding was poor, while the bearing capacity of the joint was low; when the holding time was suitable, the bearing capacity of the joint reached the corresponding highest, while the fracture mode conformed to the equal load-carrying design; when the brazing holding time was quite long, the bearing capacity of the joint remained at a high level, but the fracture mode was the same as the holding time was quite short.

Effect of the Deformation and Heat Treatment on the Microstructural Evolution and Mechanical Properties of Mg-4%Y Alloy

This study aimed to evaluate the effects of extrusion process and subsequentheat-treatment on microstructural evolution and mechanical properties of Mg-4%Y alloy. Theresults showed that the dynamic recrystallization occurred during extrusion, the microstructure istiny equiaxial grains, the shearing stripes and parallel streamlines which distribute along theextrusion direction are especially obvious. The tensile curve has obvious yield phenomenon. Afterannealing, parallel streamlines disappear, the yield phenomenon of tensile curve eliminates, theyield strength(σ0.2) and the tensile strength(σb) decrease, the plasticity increases. The underneathmechanism for mechanical properties can be ascribed to the weak pining effect of second-phaseparticles on the movement of dislocation and release of the pile-up dislocations.