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Sasan Hasanlou,Majid Vaseghi,Mahmood Sameezadeh 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6
This study aimed to investigate the fracture and hardening behaviors of transformation induced plasticity (TRIP) steel atdifferent heat-treatments using the uniaxial tensile test and the necking correction method to study the effects of variousheat treating procedures and strain rates in the microstructural evaluation, mechanical properties, and fracture behavior ofthe investigated steel. The uniaxial tensile tests were performed on samples heat-treated through different procedures andstrain rates in the range of 0.005–5 s−1. It was observed that the strain rate slightly affects the formability of TRIP steel indifferent heat-treatment procedures. The obtained results showed that the H3 sample in which the samples austenitized at900 °C for 22 min then soaked at 400 °C for 1 h and finally quenched in oil at 50 °C and cooling at ambient temperature hadthe highest strain fracture. The nucleation and growth of voids, as well as the dynamic equilibrium between strain hardeningand recovery, were reasons for fracture strain increment from 0.005 to 0.1. However, fracture strain decreased at the strainrate of 0.1–5 s−1 due to the decrease of ductility. Also, TRIP steel characterizations were used for modeling the displacementand stress of the anti-roll bar by ANSYS 19.2 parametric language and Solid-Works. The displacement and stress results ofTRIP steel were compared to SAE Class 550 and Class 700 grades of steel.
Softening and Microstructure Evolution of Pure Copper Disks Processed by High Pressure Torsion
Seyed Amin Hosseini Kahnooj,Majid Vaseghi,Mahmood Sameezadeh 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11
In this study after designing and manufacturing HPT’s anvils, copper disks with more than 99.99% purity were processedby HPT at two selected pressures for various turns. The results showed that the softening of Cu processed disks occurs veryquickly. Also, the softening range expanded from near the edge to near the center of processed disks, and this range was moreexpanded by increasing turns and pressure. The uniformity of hardness along the radius of the processed disk was obtainedat a pressure of 1.25 GPa for 2 turns. Microhardness-equivalent strain plots showed a maximum pick at the strain of 2–3 andthen it reached a steady-state at the equivalent strain of 5–6. Mean crystallite size and dislocation density were calculatedusing the Rietveld refinement method from XRD patterns. The results illustrated mean crystallite size and dislocation densitydue to recrystallization and recovery decreased by increasing pressure and turn. These results could help long-time applicationsof copper processed by SPD processes that are unusable due to long-time softening.