Effect of Grain Size on Fatigue Behavior in AZ61 Mg Alloys Fabricated by MDFing

Abstract

Magnesium (Mg) alloy AZ61 was multi-directionally forged (MDFed) under decreasing temperature conditions using a die. The average grain size decreased with increasing MDFing pass number. The initial grains size of 21.6 μm in the as-annealed specimen decreased gradually during MDFing and an average grain size of 0.3 μm could be attained after MDFing for 8 passes. The tensile strength and Vickers hardness were improved with increasing pass number from 1 to 8. Hall-Petch relationship was held for those static mechanical properties. Subsequently, tension-tension axial loading fatigue tests were performed using the as-annealed specimen and MDFed ones to 1, 3, 6 and 8 passes in which cumulative strains were 0.8, 2.4, 4.8 and 6.4 respectively. Fatigue strengths were highly improved by MDFing with increasing pass number of forging from 1 to 3. However, the improvement looked almost saturated over the pass number of 3. The observed breaking-up of the Hall-Petch relationship concerning with fatigue limits was attributed to grain-boundary sliding followed by crack initiation and propagation along grain boundaries.

Severe Plastic Deformation of Nanocrystalline AZ61 Magnesium Alloy Composites Prepared by Spark Plasma Sintering Technique

“…The ultra-fine-grained structure of nanocrystalline (nc) metals has demonstrated good qualities against chemical, physical, and mechanical stress, making them a significant component of current technology [1]. Additionally, prior research on nanocrystalline metals has demonstrated an increase in strength under stress and compression [2] [3]. as well as great ductility at room temperature [4].…”

“…Since magnesium (Mg) alloys with a density of 1.74 g/cm3 are known for having a low weight to strength ratio, they have found extensive use, particularly in the automotive and aerospace industries. These days, biodegradable implants are made of magnesium alloy material [2]. Additionally, because magnesium alloys have a higher tensile strength than aluminum alloys, they are utilised in place of aluminum alloys [3].…”

“…A technique used to strengthen magnesium alloys is called severe plastic deformation (SPD). Through a variety of techniques, including ARB, HPT, SPS, ECAP, and others, the researchers have been successful in obtaining the SPD of magnesium alloys [2][3][4][5][6][7][8][9][10]. The microstructure of the magnesium alloy (Mg-6%Al-0.5%Zn-0.…”

Effect of heat treatment at the temperature above β‐transus on the microstructures and fatigue properties of pure Ti

“…There are mainly two ways for the strengthening of CP-Ti without adding any alloying elements, namely, one is sever plastic deformation and the other is heat treatment. There have been some attempts to increase the strengths of CP-Ti through sever plastic deformation processes, such as equal-channel angular pressing (ECAP), 6,7 accumulative roll bonding (ARB), 8,9 multidirectional forging (MDF) [10][11][12] and so on. The authors had reported that the mechanical properties of CP-Ti could be highly improved by MDF, and the properties were comparable to Ti-6Al-4V.…”

High Cycle Fatigue Properties of Multi-Directionally Forged Commercial Purity Grade 2 Ti Plate

“…Recently, sever plastic deformation (SPD) such as equal channel angular pressing (ECAP) [2] and high pressure torsion (HPT) [3] attract attention as strengthening methods of metals. Multi-directional forging (MDFing) is one of the SPD methods, in which materials are forged with changing forging axes for 90 degrees pass by pass [4][5][6]. The major advantage of MDF is fabrication of large components.…”