The Microstructural Evolution and Special Flow Behavior of Ti-5Al-2Sn-2Zr-4Mo-4Cr During Isothermal Compression at a Low Strain Rate

2017 ◽  
Vol 26 (9) ◽  
pp. 4227-4234
Author(s):  
J. Z. Sun ◽  
M. Q. Li ◽  
H. Li
2016 ◽  
Vol 877 ◽  
pp. 575-580
Author(s):  
Li Zhen Yan ◽  
Yong An Zhang ◽  
Bai Qing Xiong ◽  
Zhi Hui Li ◽  
Xi Wu Li ◽  
...  

The hot deformation behavior of an Al-0.92Mg-0.78Si-0.20Cu-0.60Zn alloy was studied by isothermal compression in the temperature range from 350 to 500 oC with strain rates of 0.01-10s-1 on Gleeble-1500 thermo-mechanical simulator. The microstructural evolution during hot deformation was investigated by electron back-scatter diffraction (EBSD). The results show that the strain rate and deformation temperature have significant influence on flow behavior, and the flow stress increases with increasing strain rate and decreasing deformation temperature. Processing map at the strain of 0.7 is obtained and exhibits three peak efficiency domains (380-420 oC at 0.01s-1, 480-500 oC at 0.01s-1 and 450-500 oC at 0.1-0.32s-1). According to the processing map and microstructure observation, the optimized processing condition of hot deformation for the alloy is at 450-500 oC and strain rate of 0.1-0.32s-1. The homogenized ingot is hot rolled at 480 oC with a strain rate of 0.1s-1 based on optimized deformation parameters. The fraction of high-angle grain boundary is 35.2%, which is in accord with microstructure after hot deformed at 500 oC with a strain rate of 0.1s-1.


Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1517
Author(s):  
Hailong Yi ◽  
Yifan Zhang ◽  
Renyi Xie ◽  
Mengyuan Bi ◽  
Daixiu Wei

High entropy alloys (HEAs) containing multi-principal metallic constituents have attracted much attention. A good understanding of their hot-deformation behavior and recrystallization mechanism is the prerequisite for microstructures tuning and for optimizing mechanical performance. Here, the flow behavior and recrystallization mechanism of the N-doped and C-doped face-centered cubic phase HEAs are produced at high temperatures by hot-compression at 1123–1273 K, with strain rates of 0.1–0.001 s−1. Constitutive equations were successfully constructed to reveal flow behavior, and stress-strain curves were predicted using strain compensated polynomial functions. Discontinuous and continuous dynamic recrystallization proceeded concurrently when compressed at a low temperature and high strain rate, whereas discontinuous recrystallization, which occurs at primary grain boundaries, became predominant at a high temperature and low strain rate, significantly contributing to the refinement and homogenization of the grains. For this reason, a relatively high temperature and a low strain rate, in which the recrystallized grains exhibit equiaxed morphology and very weak texture, are more suitable for refining grains. The average size of the grains was approximately 10 μm. This study sheds light on grain optimization and mechanical properties through thermomechanical processing.


2012 ◽  
Vol 26 (32) ◽  
pp. 1250181
Author(s):  
ZHIYI LIU ◽  
XU CHEN ◽  
YANHUI HOU ◽  
SUKBONG KANG

Microstructural evolution and flow behavior of twin-roll cast AZ41 magnesium alloy during hot compression were characterized by employing deformation temperature of 300°C, 350°C and 400°C, and strain rate ranging from 10-3 to 10-2 s -1. When compressed at different temperature (300°C, 350°C and 400°C) and strain rate (10-3 and 10-2 s -1) all stress strain curves showed a flow softening behavior before strained to 0.51 due to dynamic recrystallization, even though concurrent twinning was quite active. Twinning contributed to the flow hardening behavior appeared during the end of hot compression (ε > 0.51) at a strain rate of 10-2 s -1 and elevated temperature (300°C, 350°C and 400°C) in spite of the softening effect of concurrently occurred dynamic recrystallization. TEM image showed that discontinuous recrystallization occurred when deformed at elevated temperature as high as 400°C and the strain rate ranging from 10-2 to 10-3 s -1. It is suggested that dislocation slip, twinning and recrystallization develop in a cyclic mode from initial stage to the end of hot compression.


2011 ◽  
Vol 239-242 ◽  
pp. 2395-2398 ◽  
Author(s):  
Hui Zhong Li ◽  
Xiao Peng Liang ◽  
Min Song ◽  
Min Zeng

The flow behavior of a 7039 aluminum alloy and the corresponding microstructural evolution during hot deformation were studied by Gleeble-1500 thermal simulation tests, EBSD and TEM observations with temperatures ranging from 300 °C to 500 °C under strain rates from 0.01 s-1 to 10 s-1. It has been shown that the flow stress increases with the decrease in the deformation temperature and increase in the strain rate. The degree of dynamic recrystallization (DRX) increases with the increase in the deformation temperature and strain rate in 7039 aluminum alloy. The complete dynamic recrystallization occurs at 500 °C with a strain rate of 10 s-1.


2013 ◽  
Vol 699 ◽  
pp. 808-812
Author(s):  
Lei Chen ◽  
Xiao Cong Ma ◽  
Ming Jia Wang ◽  
Hua Gui Huang

The flow behavior and microstructural evolution of an as-wrought duplex stainless steel has been investigated by Gleeble-3500 thermal-mechanical simulator within the temperature range of 950-1200°C and the strain rate range of 0.1-10s-1. The flow curves exhibited a peak stress characteristic followed by dynamic softening and the strain for appearance of steady stress is bigger at higher strain rate than at lower strain rate. The apparent activation energy (Q) and the apparent stress exponent (n) of the test steel are obtained to be about 462 kj/mol and 3.95, respectively. The relationship between peak stress (σp) and Zener-Holomon parameter (Z) is obtained, whereby the σp can be predicted at differern hot working conditons. The results of microstructural observation show that the austenite softens by the dynamic recrystallization (DRX) which can be dominantly responsib le for dynamic softening, while the ferrite phase mainly continues to exhibit dynamic recovery (DRV).


2013 ◽  
Vol 677 ◽  
pp. 188-191
Author(s):  
Horng Yu Wu ◽  
Feng Jun Zhu ◽  
Chui Hung Chiu ◽  
Hsu Cheng Liu ◽  
Cheng Tao Wu

Hot deformation characteristics of 316 stainless steel were investigated at elevated temperatures. Hot compressive tests were carried out in the temperature and strain rate ranges from 900 to 1100 °C and 1 × 10−1 to 1 s–1, respectively. Correlation between the flow behavior and the microstructural evolution was analyzed. The flow behavior showed that the softening mechanisms were related to the dynamic recovery (DRV), dynamic recrystallization (DRX), and grain growth. Flow behavior analyses and microstructural observations indicated that DRV was the major softening mechanism at high strain rates and low temperatures. Dynamic softening proceeded via a combination of DRV and DRX at intermediate strain rates and temperatures. The contribution of DRV to the softening effect decreased with decreasing strain rate (or increasing temperature). Grain growth was the major softening effect at low strain rates and high temperatures.


2017 ◽  
Vol 5 (3) ◽  
pp. 8
Author(s):  
KUMAR DINESH ◽  
KAUR ARSHDEEP ◽  
AGGARWAL YUGAM KUMAR ◽  
UNIYAL PIYUSH ◽  
KUMAR NAVIN ◽  
...  

2010 ◽  
Vol 108-111 ◽  
pp. 494-499
Author(s):  
Ying Tong ◽  
Guo Zheng Quan ◽  
Gang Luo ◽  
Jie Zhou

This work was focused on the compressive deformation behavior of 42CrMo steel at temperatures from 1123K to 1348K and strain rates from 0.01s-1 to 10s-1 on a Gleeble-1500 thermo-simulation machine. The true stress-strain curves tested exhibit peak stresses at small strains, after them the flow stresses decrease monotonically until high strains, showing a dynamic flow softening. And the stress level decreases with increasing deformation temperature and decreasing strain rate. The values of strain hardening exponent n, and the strain rate sensitivity exponent m were calculated the method of multiple linear regression, the results show that the two material parameters are not constants, but changes with temperature and strain rate. Then the two variable material parameters were introduced into Fields-Backofen equation amended. Thus the constitutive mechanical discription of 42CrMo steel which can accurately describe the relationships among flow stress, temperature, strain rate, strain offers the basic model for plastic forming process simulation.


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