Gao Feng Quan

Process and Property of Superplastic Mould Forged AZ80 Wheel Hub

Automobile wheel hub of Mg alloy with single-step extrusion-forging process was developed, and the microstructure and mechanical properties after heat treatment were investigated. The forged hubs have a hub wall of as thin as 3mm, and 4-7kg lighter than that of Al alloy wheel hub with a same size and design of each wheel hub, that would lead remarkable reduction of fuel consumption. The tensile strength larger than 308 MPa, good corrosion fatigue and impacting resistance sampled from the hubs obtained.

Effects of Hot Extrusion and Heat Treatment on Mechanical Properties and Microstructures of AZ91 Magnesium Alloy

The effects of heat treatment on the microstructure, tensile property and fracture behavior of as-extruded AZ91 magnesium alloy were studied by OM and SEM. The results show that the grain of as-cast AZ91 alloy is refined by extruding and dynamic recrystallization, and the mechanical properties increase obviously. The ductility is significantly enhanced after solution treatment of the as-extruded AZ91 alloy, tensile strength is almost the same before and hardness is significantly reduced after solution treatment and artificial aging treatment. The tensile strength reduced and the ductility is significantly enhanced of as-extruded AZ91 magnesium alloy after annealing processes. The fracture surface of as-extruded AZ91 magnesium alloy has the mixture of ductile and brittle characteristic. But after T6 or annealing treatment, its dimple number increases evidently.

The FEM Analysis for Magnesium Alloy Honeycomb Panel

The numerical modeling and modal analysis had been investigated on vibration of magnesium alloy honeycomb panels. With a simplified model of honeycomb panel, imposing the boundary and initial conditions, the distribution of the natural frequency and inherent vibration mode of the honeycomb sample could be simulated by using Lanczos method, the summit amplitudes and the most dangerous points are found. The effective factors such as materials modulus, the density as well as the assembling all contribute to the analyzed results. The vibration modes and the basic vibration frequencies were analyzed. According to the analysis, the risk-reduction program is proposed.

Comparative Study on Compression Deformation Behaviors of Cast and Extruded AZ31 Alloys

Compression properties, microstructure evolution and deformation behaviors of cast and extruded AZ31 alloys are investigated. The results show that compressive yield stress, ultimate strength and ultimate compression ratio between extruded and cast AZ31 alloy are quite different. The yielding pattern of as-cast AZ31 alloy is continuous, and the yield pattern of extruded AZ31 alloy demonstrate an obvious yielding plateau mode. The angle between the fractures and specimens axis of as-cast and extruded AZ31 alloy is about 45°. A mass of reliefs and damage can be found on the specimen surface of as-cast AZ31 alloy and the twinning is main deformation sign in as-cast AZ31 alloy as seen a rough surface. The slip activity might be a predominant deformation mechanism in extruded AZ31 alloy judged by smooth surface after fracture.

Effect of Hot Extrusion Process on Microstructure and Properties of Wide and Hollow AZ31 Magnesium Alloy Profiles

According to the profile section of transport equipment, the wide and hollow AZ31 magnesium alloy profiles was self-designed. Extrusion molding performance of the profiles, the law of microstructure and mechanical properties were studied when billets pretreatment and extrusion temperature were changed. The conclusions are as follows: (1) The grains of AZ31 profiles extruded by pre-extrusion billet are smaller and the strength is better, its maximum tensile strength is 280MPa. (2) Other processes being equal, the grains of AZ31 profiles are smaller and strength is higher, but the plastic is bad, when the extrusion temperature is 300°C. However, both strength and ductility of AZ31 profiles are better, when the extrusion temperature is 350°C. (3) Wide and Hollow AZ31 profiles perform significant heterogeneity and anisotropic characteristics on mechanical properties.

Effect of Pre-Strain on Fatigue Behaviour of AZ31 Mg Alloy

Mg Alloys Are the Lightest Structural Alloys with Excellent Castability and Machinability as Well as Highest Specific Strength and Stiffness. According to their Hexagonal close Packed Crystal Lattice there Is an Urgent Requirement of Mechanical Property Evaluation Method for Industrial Application, Particularly to Wrought Mg Alloys. Cyclic Loading Is a Very Popular Mode for Most Structural Application Situations. Recent Development of Fatigue Examination of Extruded Profile Has Shown that Mg Alloys Show Not so Ideal Fatigue Property. so that the Further Detailed Study on Cyclic Loading for Plastic Deformed Mg Alloys Is Needed. Tension-Tension Fatigue Tests Were Conducted on Pre-Strained AZ31 Mg Alloys that Produced by Rolling and Extruding Procedures. the Results Show that the Compressive Plastic Deformation Leads to Reduction of Fatigue Life/limit Significantly. SEM Analysis on Fatigue Fracture Surfaces Indicates that the Fatigue Cracks Initiate in the Surface or Sub-Surface of Dramatically Deformed Zones. the Microstructure Analysis Reveals that the Pre-Strain Brings More Abundant Twinning Bands with the Increase in Pre-Strain. the Decrease in Fatigue Life Demonstrates Also some Critical Feature with the Pre-Strain Level.

Study on Compression Behaviour of AZ31 Magnesium Alloy at Room-Temperature

The microstructure, surface morphology, compression properties, deformation behaviour and strain hardening exponent of as-cast and as-extruded AZ31 Mg alloy after different annealing treatments were investigated. The results show that the compression properties are great different between cast AZ31 alloy and extruded AZ31 alloy. Extruded AZ31 alloy is discontinuous yield and on the surface no signs of damage have been observed; on the contrast, cast AZ31 alloy is continuous yield and shows wavy patterns, and the surface cracks can be easily found. In addition, there is a linear relationship between the strain hardening exponent in first deformation stage and the yield ratio. Further more, the twinning mechanism plays very different role in cast AZ31 alloy and extruded AZ31 alloy.

Damage Study on AZ31 Mg Alloy under Bending Load

The microstructure, mechanical properties and damage morphology of as-cast and as-extruded AZ31 Mg alloy under different annealing treatments were investigated. The result of three-point bending test showed that the as-extruded magnesium alloy after annealing treatment followed by 300°C×30min can obtain a good mechanical properties and fine uniform grains. There are clear surface macro-cracks and emboss, the micro-cracks and cavities generated in the vicinity of the main crack, the main cracks of as-extruded samples arises from the maximum compressive stress position ,but as-cast samples arises from the maximum tensile stress position. The main crack of magnesium alloys is extended from the edge to the center of the specimen. This is because the crack propagates along grain boundaries or twin boundaries, and the cracking process will be obstructed by dislocation and/or the second phase particles

Microstructures and Mechanical Properties of Mg-Al-Zn-Y Alloys

The microstructures and mechanical properties of quasicrystal reinforced Mg-Al-Zn-Y alloys with different Y and Zn contents were investigated. The results show that I-phases and Mg17Al12 phases form in all alloys. When Y content exceeds 1.0 at.%, the blocky Al2Y particles form, and it is disadvantageous to improve tensile strength and elongation rate. The tensile failure modes of Mg-Al-Zn-Y alloys are quasi-cleavage fracture. The tensile strength and elongation rate increase firstly and then decrease with increasing Y and Zn contents. When Y content reaches 1.0 at.%, the tensile strength and elongation rate achieve the highest values.

A Study on Brazing Process and Mechanical Properties of AZ31 Magnesium Alloy

The brazing process of magnesium alloy AZ31 was studied, and the mechanical properties of the weld were examined, and the main factors were analyzed through brazing furnace tests in this work. Only with the protection of self-made brazing flux, a lap joint with the average shear strength of 30MPa could be obtained in an ordinary resistance furnace without inert gas protection, which is much better than that without flux in which the shear strength is lower than 10MPa.