Study on the Critical Damage Value and Processing Map of AZ80 Magnesium Alloy Forming at Elevated Temperatures

In the present research, a series of AZ80 magnesium alloy billets were compressed with 60% height reduction on hot process simulator at temperatures of 473,523,573,623,673,723K under strain rates of 0.001, 0.01, 0.1,1 and 10s-1. The value of the Cockcroft-Latham equation, i.e. critical damage value, was calculated from the finite element calculations for the compression tests. The results show that the critical damage value is not a constant but varies in a range from 0.1397 to 0.4653. Meanwhile, the processing maps based on the Dynamic Material Modeling (DMM) were constructed. From the processing maps, the optimal deformation processing parameters are the deformation temperatures ranging from 573 to 623K and strain rates ranging from 0.001 to 0.01s-1 in view of improving the mechanical properties of AZ80 alloy component.

A Study on Processing Map and Flow Stress Model of AZ80 Magnesium Alloy Forming at Elevated Temperature

Quantities AZ80 magnesium alloy billets were compressed with 60% height reduction on hot process simulator at 200,250,300,350,400,450°C under strain rates of 0.001, 0.01, 0.1,1 and 10s-1.The processing maps based on the Dynamic Material Modeling (DMM) were constructed, which is useful to analyze the deformation mechanism and the destabilization mechanism of AZ80 alloy. If the mechanical property of AZ80 alloy is taken into consideration, the optimal deformation processing parameters from the processing maps are the deformation temperatures ranging from 300 to 350°C and strain rates ranging from 0.001 to 0.01s-1. Meanwhile, a flow stress model with eight parameters is used to characterize the dynamic recrystallization strain softening of AZ80 alloy.

Processing Map and Flow Localization of a TiAl/TiB2 XD Composite

Isothermal compression tests were conducted on a particulate reinforced Ti-44Al–3V+7.5v/o TiB2 composite produced by the XD® process over wide ranges of temperatures and strain rates, 1050 to 1300 C and 0.001 to 1.0 s-1, respectively. Flow localization parameter analysis was performed to analyze the flow behavior of the composite under various processing conditions, and the results were compared to those by dynamic material modeling. Microstructural characterization was also conducted to correlate the flow behavior with post-deformation microstructures. With combined information on flow behavior and microstructures, the processing condition for relatively stable flow and uniform microstructure was determined to be 1300 C and 0.01 to 0.1 s-1.

Workability of A Dual Phase Titanium Aluminide-TiB2 XdTM Composite

ABSTRACTHigh temperature compression tests have been performed on a Ti-44a/o Al-3a/o V-7.5v/o TiB2XD composite over the temperature range 1000 to 1300°C and the strain rate range 10-3 to 10s-1. The workability of this material for metalforming processes was determined using both dynamic material modeling and workability testing approaches to cover both internal and surface cracking. At higher temperatures and strain rates internal fracture occurred in the material, while at lower temperatures and higher strain rates surface cracks occurred. Use of lower temperatures and strain rates inhibited internal instabilities and surface cracking in the composite. A finite element model (FEM) was developed to describe the stress and strain states during the deformation process. Mechanical flow behavior obtained from the compression tests was used as input to the model. A fracture criterion developed from Kuhn's surface crack equation was coupled with the FEM model to predict bulk formability in a forging process.