Numerical simulation of coupled thermo-electrical field for 20 kA new rare earth reduction cell

To solve the problems of high energy consumption,low efficiency and short service life of conventional rare earth reduction cells,a 20 kA new rare earth reduction cell(NRERC)was presented.The effects of the anode-cathode distance(ACD)and electrolyte height(EH)on the thermo-electrical behavior of the NRERC were studied by ANSYS.The results illustrate that the cell voltage drop(CVD)and the temperature will rise with a similar tendency when the ACD increases.Also,the temperature rises gradually with EH,but the CVD decreases.Ultimately,when the ACD is 115 mm and the EH is 380 mm,the CVD is 4.61 V and the temperature is 1109.8℃.Under these conditions,the thermal field distribution is more reasonable and the CVD is lower,which is beneficial to the long service life and low energy consumption of the NRERC.

Surface integrity evolution of machined NiTi shape memory alloys after turning process

Owing to their shape memory effect and pseudoelasticity,NiTi shape memory alloys(SMAs)are widely used as functional materials.Mechanical processes particularly influence the final formation of the product owing to thermal softening and work-hardening effects.Surface integrity is an intermediate bridge between the machining parameter and performance of the product.In this study,experiments were carried out on turning NiTi SMAs at different cutting speeds,where surface integrity characteristics were analyzed.The results show that a higher cutting speed of 125 m/min is required to turn NiTi SMAs based on the evaluation of surface integrity.The degree of work hardening is higher at 15 m/min.Consequently,as a primary effect,work hardening appears on the plastic deformation of the machined samples,leading to dislocations and defects.As the cutting speed increases,the thermal softening effect exceeds work hardening and creates a smoother surface.A stress-induced martensitic transformation is considered during the turning process,but this transformation is reversed to an austenite from the X-ray diffraction(XRD)results.According to the differential scanning calorimetry(DSC)curves,the phase state and phase transformation are less influenced by machining.Subsequently,the functional properties of NiTi-SMAs are less affected by machining.

Influences of processing parameters and heat treatment on microstructure and mechanical behavior of Ti-6Al-4V fabricated using selective laser melting

Selective laser melting(SLM)has provided an alternative to the conventional fabrication techniques for Ti-6Al-4V alloy parts because of its flexibility and ease in creating complex features.Therefore,this study investigated the effects of the process parameters and heat treatment on the microstructure and mechanical properties of Ti-6Al-4V fabricated using SLM.The influences of various process parameters on the relative density,tensile properties,impact toughness,and hardness of Ti-6Al-4V alloy parts were studied.By employing parameter optimization,a high-density high-strength Ti-6Al-4V alloy was fabricated by SLM.A relative density of 99.45%,a tensile strength of 1188 MPa,and an elongation to failure of 9.5%were achieved for the SLM-fabricated Ti-6Al-4V alloy with optimized parameters.The effects of annealing and solution aging heat treatment on the mechanical properties,phase composition,and microstructure of the SLM-fabricated Ti-6Al-4V alloy were also studied.The ductility of the heat-treated Ti-6Al-4V alloy was improved.By applying a heat treatment at 850℃ for 2 h,followed by furnace cooling,the elongation to failure and impact toughness were found to be increased from 9.5%to 12.5%,and from 24.13 J/cm^(2)to 47.51 J/cm^(2),respectively.