Granularity-induced plastic deformation mechanism of pure polycrystalline cubic boron nitride

Ti-6Al-4V components are the most widely used titanium alloy products not only in the aerospace industry, but also for bio-medical applications. The machine-ability of titanium alloys is impaired by their high temperature chemical reactivity, low thermal conductivity and low modulus of elasticity. Polycrystalline cubic boron nitride represents a substitute tool material for turning titanium alloys due to its high hardness, wear resistance, thermal stability and hot red hardness. For determination of suitable cutting parameters in dry turning Ti-6AL-4V alloy by Polycrystalline cubic boron nitride cutting tools, the samples, 300mm in length and 100mm in diameter, were dry machined in a lathe. The turning suitable parameters, such as cutting speed, feed rate and cut depth were determined according to workpieces surface roughness and tools flank wear based on orthogonal experimental design. The experiment showed that the cutting speed in the range of 160~180 m/min, the feed rate is 0.15 mm/rev and the depth of cut is 0.20mm, ideal workpiece surface roughness and little cutting tools flank wear can be obtained.

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Effect of Aging Treatment on Dynamic Behavior of Mg-Gd-Y Alloy

International Journal of Nonlinear Sciences and Numerical Simulation ◽

10.1515/ijnsns.2011.097 ◽

2012 ◽

Vol 13 (2) ◽

pp. 111-116

Author(s):

Lin Wang ◽

Qiao-Yun Qin ◽

Fan Zhang ◽

Cheng-Wen Tan

Keyword(s):

Plastic Deformation ◽

Rare Earth ◽

Magnesium Alloy ◽

Dynamic Behavior ◽

Deformation Mechanism ◽

Dynamic Properties ◽

Dynamic Compression ◽

Aging Treatment ◽

Dislocation Slip ◽

Plastic Deformation Mechanism

Abstract Magnesium alloy is very attractive in many industrial applications due to its low density. The structure-property relationships of the magnesium alloy under quasi-static loading have been extensively investigated. However, the dynamic behavior, particularly the mechanism of high-rate plastic deformation, of the magnesium alloy requires more in-depth investigations. In this paper, the effect of aging treatment on the quasi-static and dynamic properties of a typical rare earth Mg-Gd-Y magnesium alloy is investigated. In particular, the plastic deformation mechanism under dynamic compression loading is discussed. Split Hopkinson Pressure Bar (SHPB) was used to carry out dynamic compression tests with controllable plastic deformation by using stopper rings. The experimental results demonstrate that both static and dynamic properties of the Mg-Gd-Y alloy vary under various aging treatment conditions (under-aged, peak-aged and over-aged conditions), due to two different kinds of second phases: remnant micro size phase from solid solution treatment and nano precipitation from aging treatment. The results of microstructure characterization and statistic analysis of the metallographic phase are presented. The area fraction of the twinned grains increases due to aging treatment and dynamic loading. The main plastic deformation mechanism of the rare earth Mg-Gd-Y magnesium alloy is possibly dislocation slip, rather than twinning for the conventional AZ31 magnesium alloy under high strain rate loading.

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