A New Modified Cyclic Extrusion Channel Angular Pressing (CECAP) Process for Producing Ultrafine-Grained Mg Alloy
- PDF / 5,038,586 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 51 Downloads / 238 Views
ORIGINAL ARTICLE
A New Modified Cyclic Extrusion Channel Angular Pressing (CECAP) Process for Producing Ultrafine-Grained Mg Alloy Siroos Ahmadi1 • Vali Alimirzaloo1 • Ghader Faraji2 • Ali Donyavi3
Received: 12 April 2020 / Accepted: 15 July 2020 The Indian Institute of Metals - IIM 2020
Abstract In this study, a new modified cyclic extrusion channel angular pressing (CECAP) process with multi-pass capability is presented for producing ultrafine-grained (UFG) Mg alloy. In this method, an additional extrusion stage with a low extrusion ratio is added at the end of the CECAP process to enhance hydrostatic stresses, equivalent strain, and facilitation of the process implementation. The experimental results showed a remarkable grain refinement with a relatively uniform distribution of microstructure and b-phase in the new CECAP processed sample. The average grain size decreased from *75 lm in annealed condition to 4.5 lm and 3.5 lm in CECAP and new CECAP processes, respectively. Also, more dispersion of the b-phase with smaller sizes was observed in the processed microstructure. The hardness and its uniform distribution were increased significantly. The compressive yield stress (CYS) was enhanced to about 153.3 MPa from the initial value of *85 MPa. Also, both the strength and ductility of the new CECAP processed sample were higher than those of CECAP processed one. These excellent properties might attribute to higher hydrostatic compressive stresses resulting from the last low ratio extrusion stage which was almost 50% higher in the new CECAP process.
& Ghader Faraji [email protected] 1
Department of Mechanical Engineering, Urmia University, Urmia 57153165, Iran
2
School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 11155-4563, Iran
3
Department of Industrial Engineering, Urmia University, Urmia 57153165, Iran
Keywords New CECAP process AM60 Mg alloy FEM Strain distribution Hydrostatic compressive stress
1 Introduction Severe plastic deformation (SPD) methods have been used to enhance the efficiency of metals [1, 2]. The equal channel angular press (ECAP) process is one of the most effective techniques for the improvement in the mechanical properties via refining the microstructure of metals in recent years [3–5]. However, the results from the previous researches showed a non-uniform distribution of strain at the sample section, despite the proven effectiveness of the ECAP process in improving the mechanical properties [6–8]. Therefore, new mechanical methods have been introduced by researchers. One of these mechanical methods is the tubular channel angular pressing (TCAP), that is used to enhance the mechanical properties of tubular components [9]. This method has been modified and introduced as a parallel tubular channel angular pressing (PTCAP) [10]. The new method has an advantage compared to the TCAP process such as more uniform distribution of strain along length and section (thickness) of the sample as well as less required pressing force. Also, the use of
Data Loading...
