Hot Deformation and Processing Maps of a High Strength Alloy Steel

2010 ◽  
Vol 97-101 ◽  
pp. 374-377 ◽  
Author(s):  
Yong Cheng Lin ◽  
Ge Liu
Keyword(s):  
Strain Rate ◽  
Alloy Steel ◽  
Power Dissipation ◽  
Hot Deformation ◽  
High Strength ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Low Alloy Steel ◽  
Average Grain Size ◽  
Forming Temperature

The hot deformation behaviors of a high strength low alloy steel have been studied using the processing map technique, which is based on the variations of efficiency of power dissipation with forming temperatures and strain rates. The results show that: (1) The average grain size of the deformed alloy steel increases with the increase of forming temperatures and decreases with the increase of strain rates. (2) The efficiency of power dissipation increases as the forming temperature is increased. However, the efficiency of power dissipation changes with strain rates in the form of bulgy parabola, and the maximum value exists at the strain rate of 0.1 . (3) A domain for reasonable dynamic recrystallization (DRX) exists in the temperature range of (1050–1150) and strain rate range of (0.01–3) , with its peak efficiency of 32% at about 1140 °C and 0.23 , which are the optimum hot working parameters for the studied high strength low alloy steel.

scholarly journals High Strain Rate Superplasticity in Al-Zn-Mg-Based Alloy: Microstructural Design, Deformation Behavior, and Modeling

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2098 ◽  
Author(s):  
Olga Yakovtseva ◽  
Maria Sitkina ◽  
Ahmed O. Mosleh ◽  
Anastasia Mikhaylovskaya
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
High Strain ◽  
Flow Behavior ◽  
Constant Strain Rate ◽  
Superplastic Forming ◽  
High Strength ◽  
Strain Rate Range ◽  
Strain Rates

Increasing the strain rate at superplastic forming is a challenging technical and economic task of aluminum forming manufacturing. New aluminum sheets exhibiting high strain rate superplasticity at strain rates above 0.01 s−1 are required. This study describes the microstructure and the superplasticity properties of a new high-strength Al-Zn-Mg-based alloy processed by a simple thermomechanical treatment including hot and cold rolling. The new alloy contains Ni to form Al3Ni coarse particles and minor additions of Zr (0.19 wt.%) and Sc (0.06 wt.%) to form nanoprecipitates of the L12-Al3 (Sc,Zr) phase. The design of chemical and phase compositions of the alloy provides superplasticity with an elongation of 600–800% in a strain rate range of 0.01 to 0.6/s and residual cavitation less than 2%. A mean elongation-to-failure of 400% is observed at an extremely high constant strain rate of 1 s−1. The strain-induced evolution of the grain and dislocation structures as well as the L12 precipitates at superplastic deformation is studied. The dynamic recrystallization at superplastic deformation is confirmed. The superplastic flow behavior of the proposed alloy is modeled via a mathematical Arrhenius-type constitutive model and an artificial neural network model. Both models exhibit good predictability at low and high strain rates of superplastic deformation.

Development of Processing Maps for DC Cast Modified and Unmodified Hypereutectic Al-Si Alloys

2011 ◽  
Vol 213 ◽  
pp. 116-120
Author(s):  
Ke Zhun He ◽  
Fu Xiao Yu ◽  
Da Zhi Zhao ◽  
Liang Zuo
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Power Dissipation ◽  
Hot Deformation ◽  
High Strain ◽  
Strain Rate Range ◽  
Instability Region ◽  
Processing Maps ◽  
Unmodified Alloy ◽  
Primary Si

The hot deformation behavior of DC cast phosphorous modified and unmodified hypereutectic Al-Si alloys was studied in the temperature range of 400-500 °C and strain rate range of 0.001-1 s-1. Processing maps were developed to evaluate the efficiency of the hot deformation and to identify the instability region. The results show that the peak stresses of the unmodified alloy are higher than that of the modified alloy at the strain rate of 1 s-1 and temperatures of 400 and 440 °C. The maximum power dissipation efficiencies for both the alloys are in the region of T=480-500 °C and =0.01-0.1 s-1. The flow instabilities for both the alloys occur in regions of high strain rate about 1 s-1 and temperature about 400 and 500 °C. The instability region area of the unmodified alloy is larger than that of the modified alloy. In addition, the primary Si cracking frequencies of the unmodified alloy are higher than that of the modified alloy when compared at the same deformation rate and temperature. The coarser primary Si particles of the unmodified alloy cause higher stress concentration around them when deformed at low temperature and high strain rate.

Hot Workability of a High Strength Low Alloy Steel for Construction Application

2012 ◽  
Vol 724 ◽  
pp. 178-181
Author(s):  
Woo Young Jung ◽  
Tae Kwon Ha
Keyword(s):  
Strain Rate ◽  
Power Dissipation ◽  
High Efficiency ◽  
Hsla Steel ◽  
High Strength ◽  
Plastic Instability ◽  
Strain Rate Range ◽  
Hot Workability ◽  
Compression Tests ◽  
Increasing Temperature

The hot deformation behavior of a high strength low alloy (HSLA) steel for construction application under hot working conditions in the temperature range of 900 to 1100 and strain rate range from 0.1 to 10 s-1 has been studied by performing a series of hot compression tests. The dynamic materials model has been employed for developing the processing maps, which show variation of the efficiency of power dissipation with temperature and strain rate. Also the Kumars model has been used for developing the instability map, which shows variation of the instability for plastic deformation with temperature and strain rate. The efficiency of power dissipation increased with decreasing strain rate and increasing temperature. High efficiency of power dissipation over 20 % was obtained at a finite strain level of 0.3 under the conditions of strain rate lower than 1 s-1 and temperature higher than 1050. Plastic instability was expected in the regime of temperatures lower than 1000°C and strain rate lower than 0.3 s-1.

Hot Deformation and Processing Map of C919 Aluminum Alloy

2015 ◽  
Vol 816 ◽  
pp. 810-817
Author(s):  
Yong Biao Yang ◽  
Zhi Min Zhang ◽  
Xing Zhang
Keyword(s):  
Aluminum Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Hot Deformation ◽  
Testing Machine ◽  
Strain Rate Range ◽  
Hot Compression ◽  
Strain Rates ◽  
Processing Maps ◽  
Compression Tests

The hot deformation behaviors of Aluminum alloy C919 were studied in the present investigation. The hot compression tests for C919 were carried out in the temperature range of 350°C~470°C and strain rates range of 0.001s-1~1s-1 using GLEEBLE-1500 thermal simulate testing machine. Optical microscopy (OM) was used for the microstructure characterization. The experimental results showed that the flow stress of C919 aluminum alloy decreased with increasing temperature and decreasing strain rates and the flow stress curves tended to increase at a strain rate of 1s-1 with increasing strain, while the flow stresses kept with increasing strain at lower strain rate. The alloys were more prone to dynamic recrystallization with decreasing strain rates during hot deformation. The hot compression behavior of C919 aluminum alloy can be described as hyperbolic sine function corrected Arrhenius relation. The processing maps for the alloy were built at a strain of 0.6. The instability deformation domain occurred at temperatures range from 350°C and 380°C and at a strain rate of 0.1-1s-1. Based on the processing maps and microstructure observations, the optimum hot-working parameters were determined to be at a temperature of 470°C in the strain rate range from 0.1-0.01s−1 for the C919 aluminum alloy.

IMPROVED MECHANICAL PROPERTY OF ELECTRODEPOSITED NANOCRYSTALLINE NICKEL-COBALT ALLOY

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2285-2290 ◽  
Author(s):  
XIXUN SHEN ◽  
JIANSHE LIAN
Keyword(s):  
Strain Rate ◽  
High Strain ◽  
Rate Sensitivity ◽  
High Strength ◽  
Strain Rate Range ◽  
Nickel Cobalt ◽  
Average Grain Size ◽  
High Strain Rate Sensitivity ◽  
Small Activity ◽  
Very High

A bulk and dense nc Ni -24.7% Co with an average grain size of 15nm was fabricated by a direct current electrodeposition. This Ni -24.7% Co exhibits very high tensile strength of 1813MPa to 2232MPa with relatively good tensile ductility of 6.0%~9.6% under tensile test over a wide strain rate range of 0.417s-1 ~ 1.35×10-5s-1. The combination of high strength and good ductility should be attributed to the increased strain hardening ability induced by the addition of alloying Co element. The interaction of dislocation and grain boundaries is the rate-controlling deformation mechanism controlled in the Ni -24.7% Co based on its high strain rate sensitivity of 0.029 and small activity volume of ~14b3.

Environmental Fatigue Behaviors of SA508 Gr.1a Low Alloy Steel in 310°C Deoxygenated Water

2007 ◽  
Vol 345-346 ◽  
pp. 1039-1042 ◽  
Author(s):  
Hyun Chul Cho ◽  
Hun Jang ◽  
Byoung Koo Kim ◽  
In Sup Kim ◽  
Chang Heui Jang
Keyword(s):  
Fatigue Life ◽  
Strain Rate ◽  
Alloy Steel ◽  
Low Cycle Fatigue ◽  
Strain Rate Range ◽  
Fatigue Tests ◽  
Low Alloy Steel ◽  
Metal Dissolution ◽  
Rate Range ◽  
Temperature Water

The low cycle fatigue tests of SA508 Gr.1a low alloy steel were carried out to investigate the fatigue crack growth mechanisms in high temperature water. The fatigue life in 310oC deoxygenated water was shorter than that in air. Furthermore, the reduction in the fatigue life in 310oC deoxygenated water was enhanced with a decreasing strain rate, from 0.4 to 0.008 %/s. The ductile striations with the streamed down features, which may indicate the occurrence of the metal dissolution, were mainly observed at the strain rate of 0.008 %/s. And the flat facets and the brittle cracks, which may be evidences for the HIC, were primarily observed in the strain rate range from 0.04 to 0.4 %/s. From the analysis of microstructure, it is thought that the HIC contribute dominantly to the reduction in the fatigue life in the strain rate range from 0.04 to 0.4 %/s and the metal dissolution is mainly responsible for the reduction in the fatigue life at the strain rate of 0.008 %/s.

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