http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Dynamic ageing and the mechanical response of Al–Mg–Si alloy through equal channel angular pressing
Vaseghi, Majid,Taheri, Ali Karimi,Hong, Sun Ig,Kim, Hyoung Seop Elsevier 2010 MATERIALS AND DESIGN Vol.31 No.9
<P><B>Abstract</B></P><P>In this paper, dynamic ageing characteristics associated with the application of equal channel angular pressing (ECAP) to Al6061 alloy at elevated temperatures was investigated. Followed by ECAP, Vickers microhardness measurement on the cross-sectional planes and microstructural observations were undertaken using transmission electron microscopy. The combination of the ECAP process with dynamic ageing at both 100°C and 150°C resulted in a significant increase in hardness. The grain size was measured as ∼160nm after four passes. A comparison with the published data on the same alloy processed by ECAP at room temperature and statically aged, suggests several advantages in incorporating dynamic ageing with ECAP. These advantages consist of the ability to attain better grain refinement, increased hardness and the potential for saving time and energy.</P>
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.
Deformation Characteristics Evaluation of Modified Equal Channel Angular Pressing Processes
Yoon, Seung Chae,Nagasekhar, Anumalasetty Venkata,Yoo, Ji Hoon,Abd El Aal, Mohamed Ibrahim,Vaseghi, Majid,Kim, Hyoung Seop The Japan Institute of Metals 2010 MATERIALS TRANSACTIONS Vol.51 No.1
<P>In current studies, equal channel angular pressing process (ECAP) and modified ECAP processes are simulated under ideal conditions to compare the deformation characteristics. The deformation behaviour is more complicated and the strain induced during the processes is highly non-uniform in the modified ECAP processes except in the equal channel multi-angular pressing (ECMAP) process with Route C. The strain homogeneity is more of a possibility with ECAP and ECMAP with Route C processes. The deformation stress state is widely distributed in nature in modified ECAP processes than in conventional ECAP. In addition, the load requirements are also higher in modified ECAP processes with that of the ECAP process.</P>