Characteristic Analysis of the Stress Propagation of Metal Powder in High Velocity Compaction Using DEM

2020 ◽  
Vol 89 (4) ◽  
pp. 044602
Author(s):  
Wei Zhang ◽  
Kun Liu ◽  
Jian Zhou ◽  
Rongxin Chen ◽  
Ning Zhang ◽  
...  
Keyword(s):  
Metal Powder ◽  
High Velocity ◽  
Characteristic Analysis ◽  
Stress Propagation ◽  
High Velocity Compaction

scholarly journals Influences of the Air in Metal Powder High Velocity Compaction

2017 ◽  
Vol 95 ◽  
pp. 02001
Author(s):  
Jun Liu ◽  
Haifeng Hu ◽  
Xiaolong Luo
Keyword(s):  
Metal Powder ◽  
High Velocity ◽  
High Velocity Compaction

scholarly journals EXPERIMENTAL INVESTIGATION ON STRESS AND DIE-WALL FRICTIONAL CHARACTERISTICS OF METAL POWDER DURING HIGH-VELOCITY COMPACTION

2021 ◽  
Vol 55 (2) ◽  
pp. 163-170
Author(s):  
Wei Zhang ◽  
Kun Liu ◽  
Jian Zhou ◽  
Rongxin Chen ◽  
Ning Zhang ◽  
...  
Keyword(s):  
Metal Powder ◽  
Coefficient Of Friction ◽  
High Velocity ◽  
Side Wall ◽  
Repeated Loading ◽  
Testing Technology ◽  
The Coefficient Of Friction ◽  
Three Stages ◽  
High Velocity Compaction ◽  
The Impact

In this study, to evaluate the change in the stress and die-wall frictional characteristics during high-velocity compaction (HVC), a metal powder was subjected to HVC with a heavy hammer based on the stress-testing technology and Janssen-Walker model. The changes in the green density, stress characteristics and coefficients of friction at different impact heights were investigated. The density of green compacts increased with the increase in the impact height. The stress in the upper and lower punches and the die wall showed repeated loading and unloading. The coefficient of friction of the die wall underwent three stages and was related to powder densification. As the height position along the side wall was increased, the coefficient of friction increased gradually. With an increased impact height, the coefficient of friction increased significantly in the incomplete-molding stage but remained constant in the complete-molding stage. This work expands the theoretical basis of densification processing of a metal powder during HVC.

Research of Constitutive Relation of Metal Powder in High Velocity Compaction

2010 ◽  
Vol 97-101 ◽  
pp. 1154-1160
Author(s):  
Zou Shun Zheng ◽  
Yuan Peng Zhu ◽  
Qin Wu Xu ◽  
Xuan Hui Qu
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Metal Powder ◽  
Constitutive Relation ◽  
High Velocity ◽  
High Strain ◽  
Deformation Characteristics ◽  
Viscous Effect ◽  
Linear Spring ◽  
High Velocity Compaction

Metal powders behave high strain rate, viscous effect and first hardening then softening deformation characteristics during the forming process of high velocity compaction. The characteristics of high strain rate and viscous effect are described by composite nonlinear viscoelastic body which consists of non-linear spring, linear spring and high strain rate Maxwell element. The deformation characteristics of first hardening then softening can be described by changing the degree of the term of nonlinear spring from greater than 1 to less than 1. Constitutive relation of metal powder in high velocity compaction is established. The degree of the term of nonlinear spring is considered as a function of strain. The function is approximated by linear, quadratic and cubic polynomial and the stress-strain curves are analyzed respectively. Analysis results indicate that the constitutive equation can describe the deformation characteristics of metal powder in high velocity compaction.

scholarly journals Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 218
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zaiqiang Feng ◽  
Mingqi Tang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Velocity ◽  
Sintered Density ◽  
Sintering Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
High Velocity Compaction ◽  
Sintered Temperature

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

scholarly journals Effects of Compaction Velocity on the Sinterability of Al-Fe-Cr-Ti PM Alloy

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3005 ◽  
Author(s):  
Xianjie Yuan ◽  
Xuanhui Qu ◽  
Haiqing Yin ◽  
Zhenwei Yan ◽  
Zhaojun Tan
Keyword(s):  
Mechanical Properties ◽  
High Velocity ◽  
Alloy Powder ◽  
Sintered Density ◽  
Ti Alloy ◽  
Maximum Elongation ◽  
Nitrogen Gas ◽  
High Velocity Compaction ◽  
Ti Powder ◽  
Particle Boundary

In this research, the effects of the compaction velocity on the sinterability of the Al–Fe–Cr–Ti powder metallurgy (PM) alloy by high velocity compaction were investigated. The Al–Fe–Cr–Ti alloy powder was compacted with different velocities by high velocity compaction and then sintered under a flow of high pure (99.999 wt%) nitrogen gas. Results indicated that both the sintered density and mechanical properties increased with increasing compaction velocity. By increasing the compaction velocity, the shrinkage of the sintered samples decreased. A maximum sintered density of 2.85 gcm−3 (relative density is 98%) was obtained when the compaction velocity was 9.4 ms−1. The radial and axial shrinkage were controlled to less than 1% at a compaction velocity of 9.4 ms−1. At a compaction velocity of 9.4 ms−1, sintered compacts with an ultimate tensile strength of 222 MPa and a yield strength of 160 MPa were achieved. The maximum elongation was observed to be 2.6%. The enhanced tensile properties of the Al–Fe–Cr–Ti alloy were mainly due to particle boundary strengthening.

Quantitative investigation on force chain lengths during high velocity compaction of ferrous powder

2019 ◽  
Vol 33 (10) ◽  
pp. 1950113 ◽  
Author(s):  
Wei Zhang ◽  
Jian Zhou ◽  
Xuejie Zhang ◽  
Yan Zhang ◽  
Kun Liu
Keyword(s):  
High Velocity ◽  
Pearson Correlation ◽  
Quantitative Characteristic ◽  
Correlation Coefficients ◽  
High Strength ◽  
Force Chain ◽  
Force Chains ◽  
Low Probability ◽  
High Velocity Compaction ◽  
Chain Lengths

Force chains play an important role in linking the macro- and micro-mechanisms of powder in high velocity compaction (HVC). Force chain lengths, as an important quantitative characteristic, can describe the geometry of force chains. In this study, force chain lengths and their relation to other force chain characteristics in HVC were investigated by discrete element method. Results revealed that force chain length decreased and it can be related to the densification process of ferrous powder in HVC. Moreover, long force chains extended from top to bottom and may play a major role in supporting load, although the percentage of long force chains was low. Probability density functions of force chain lengths further showed the exponential decay. The proportion of short force chains increased and the proportion of long force chains decreased. Long force chains had high strength and can be aligned to the direction of the external load, but force chain lengths did not have clear relation to straightness. These relations were confirmed by Pearson correlation coefficients.

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