Strain-Rate-Dependent Flow Stress and Failure of an Mg-PSZ Reinforced TRIP Matrix Composite Produced by Spark Plasma Sintering

2012 ◽  
Vol 83 (6) ◽  
pp. 521-528 ◽  
Author(s):  
Sabine Decker ◽  
Lutz Krüger ◽  
Sarah Richter ◽  
Stefan Martin ◽  
Ulrich Martin
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Spark Plasma Sintering ◽  
Matrix Composite ◽  
Rate Dependent ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Dependent Flow

scholarly journals Microstructure evolution of TC4 powder by spark plasma sintering after hot deformation

2020 ◽  
Vol 39 (1) ◽  
pp. 457-465
Author(s):  
Jiangpeng Yan ◽  
Zhimin Zhang ◽  
Jian Xu ◽  
Yaojin Wu ◽  
Xi Zhao ◽  
...  
Keyword(s):  
Strain Rate ◽  
Relative Density ◽  
Spark Plasma Sintering ◽  
Hot Deformation ◽  
Tc4 Titanium Alloy ◽  
Weave Structure ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Average Relative Density ◽  
Low Strain Rate

AbstractThe cylindrical samples of TC4 titanium alloy prepared by spark plasma sintering (SPS) were compressed with hot deformation of 70% on the thermosimulation machine of Gleeble-1500. The temperature of the processes ranged from 850°C to 1,050°C, and the strain rates varied between 0.001 and 5 s−1. The relative density of the sintered and compressed samples was measured by the Archimedes principle. During hot deformation, the microstructure of the sample was observed. The results show that the average relative density of the samples was 90.2% after SPS. And the relative density was about 98% after the hot deformation of 70%. Under high temperature (>950°C), the sensitivity of flow stress to temperature was reduced. At low strain rate (0.001 s−1), the increase in the deformation temperature promoted the growth of dynamic recrystallization (DRX). At the same temperature, the increase in strain rate slowed down the growth of DRX grains. And the variation tendency was shown from the basket-weave structure to the Widmanstätten structure at a low strain rate (<0.1 s−1), with increase in the strain rate.

A Modified Peric Model for Al-Mg Alloy Sheet with Rate-Independent Initial Yield Stress at Warm Temperatures

2019 ◽  
Vol 287 ◽  
pp. 3-7
Author(s):  
Yong Zhang ◽  
Qing Zhang ◽  
Yuan Tao Sun ◽  
Xian Rong Qin
Keyword(s):  
Flow Stress ◽  
Plastic Strain ◽  
Strain Rate ◽  
Yield Stress ◽  
Constitutive Models ◽  
Mg Alloy ◽  
Initial Yield Stress ◽  
Initial Yield ◽  
Rate Dependent ◽  
Dependent Flow

The constitutive modeling of aluminum alloy under warm forming conditions generally considers the influence of temperature and strain rate. It has been shown by published flow stress curves of Al-Mg alloy that there is nearly no effect of strain rate on initial yield stress at various temperatures. However, most constitutive models ignored this phenomenon and may lead to inaccurate description. In order to capture the rate-independent initial yield stress, Peric model is modified via introducing plastic strain to multiply the strain rate, for eliminating the effect of strain rate when the plastic strain is zero. Other constitutive models including the Wagoner, modified Hockett–Sherby and Peric are also considered and compared. The results show that the modified Peric model could not only describe the temperature-and rate-dependent flow stress, but also capture the rate-independent initial yield stress, while the Wagoner, modified Hockett–Sherby and Peric model can only describe the temperature-and rate-dependent flow stress. Moreover, the modified Peric model could obtain proper static yield stress more naturally, and this property may have potential applications in rate-dependent simulations.

Spark Plasma Sintering and Strength Behavior under Compressive Loading of Mg-PSZ/Al2O3-TRIP-Steel Composites

2015 ◽  
Vol 825-826 ◽  
pp. 182-188 ◽  
Author(s):  
Lutz Krüger ◽  
Steffen Grützner ◽  
Sabine Decker ◽  
Ines Schneider
Keyword(s):  
Strain Rate ◽  
Spark Plasma Sintering ◽  
Trip Steel ◽  
Volume Fraction ◽  
Compressive Yield Strength ◽  
Strain Rates ◽  
Steel Matrix ◽  
Trip Effect ◽  
Plasma Sintering ◽  
Spark Plasma

Composite materials, which consist of a metastable austenitic TRIP-steel matrix (CrMnNi TRIPsteel; TRansformation Induced Plasticity) reinforced by alumina particles (25 vol.% ceramic, designated as AT 25/75) and reinforced by alumina and MgO partially stabilized zirconia particles (Mg-PSZ) (35 vol.% ceramic, designated as AT 25/75 + MgPSZ) were synthesized through spark plasma sintering (SPS). In the AT 25/75 + MgPSZ, the steel particles were mainly surrounded by alumina. Hence, mostly steel/alumina and alumina/MgPSZ interfaces existed. The mechanical behavior of the as-sintered samples was characterized by compression tests at room temperature and 40 °C and in a range of strain rates between 103s-1and 103s1. The influence of the ceramic content, strain rate and temperature on TRIP-effect of the steel matrix was investigated. Due to the increasing ceramic volume fraction, AT 25/75 + MgPSZ exhibits the highest compressive yield strength under all loading conditions and no strain rate sensitivity. This composite showed no measurable TRIP-effect, due to the low fracture strain. The deformation-induced α’martensite within the steel particles in pure steel and AT 25/75 primary depends on the testing temperature and the strain rate. This is attributed to an increase of stacking fault energy with rising temperature. High strain rates cause adiabatic heating, counteracting the martensitic transformation.

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