The Experts below are selected from a list of 33969 Experts worldwide ranked by ideXlab platform
Zekun Yao - One of the best experts on this subject based on the ideXlab platform.
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work Hardening Effect and strain rate sensitivity behavior during hot deformation of ti 5al 5mo 5v 1cr 1fe alloy
Materials & Design, 2015Co-Authors: Yang Nan, Houquan Liang, Yongquan Ning, Hongzhen Guo, Zekun YaoAbstract:Abstract The work-Hardening Effect and strain-rate sensitivity behavior during hot deformation have been quantitatively investigated in this present paper. Isothermal compression experiment of Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy has been conducted for verification. Linear relationship between work-Hardening rate and true strain/stress has been derived from Kocks–Mecking dislocation relation. The work-Hardening Effect shows two obvious stages with strain: steady fluctuations and linear decreasing. Obvious work-Hardening Effect could be demonstrated under lower temperatures and higher strain rates. The work-Hardening decrease at linear-decreasing regime becomes more stronger with temperature elevated and rate lowered, reverse-proportional to Zener–Hollomon parameters. Strain-rate sensitivity coefficient for hot deformation was decomposed into three parts from JMAK recrystallization kinetics. The influence of strain rate on DRX evolution has been termed as the major factor determining strain-rate sensitivity. Strain-rate sensitivity coefficients for steady-state deformation ( ɛ = 0.7) of Ti–5Al–5Mo–5V–1Cr–1Fe alloy have been characterized as a function of deformation parameters and strain-rate sensitivity has been identified more obvious with temperature elevated and rate lowered.
Xiao Zhang - One of the best experts on this subject based on the ideXlab platform.
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high strain rate plastic deformation and fracture behaviour of ti 5al 5mo 5v 1cr 1fe titanium alloy at room temperature
Mechanics of Materials, 2018Co-Authors: Chun Ran, Pengwan Chen, Wangfeng Zhang, Yanlong Liu, Xiao ZhangAbstract:Abstract To study the plastic deformation and fracture behaviour of Ti-5Al-5Mo-5V-1Cr-1Fe (Ti-55511) alloy under high strain rate loading conditions, a series of dynamic compression tests on Ti-55511 alloy have been performed at constant strain rates ranging from 350 s −1 to 2900 s −1 by means of split Hopkinson pressure bar technique at room temperature. The different strain and strain rate loading conditions are realized by changing the length and velocity of the striker bar, and high intensive localized shear region is induced in Ti-55511 alloy. The dynamic compression stress-strain response, strain rate Hardening Effect and strain rate sensitivity, and the fracture behaviour are discussed. The experimental results demonstrate that: The strain rate Hardening Effect and strain rate sensitivity of Ti-55511 alloy are apparent; Brittle shear bands form at high strain rate loading conditions, and the formation of a shear band does not mean the occurrence of phase transformation; Collapse of the specimens occurs along a plane inclined at an angle of about 45° to the compression axis at room temperature for both quasi-static and dynamic compression loading; The shear-compression zone and tension-shear-compression zone coexist in the fracture surface, and collapse of the specimens is attributed to shear failure mechanism for Ti-55511 alloy under compression loading at room temperature.
Yongquan Ning - One of the best experts on this subject based on the ideXlab platform.
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work Hardening Effect and strain rate sensitivity behavior during hot deformation of ti 5al 5mo 5v 1cr 1fe alloy
Materials & Design, 2015Co-Authors: Yang Nan, Houquan Liang, Yongquan Ning, Hongzhen Guo, Zekun YaoAbstract:Abstract The work-Hardening Effect and strain-rate sensitivity behavior during hot deformation have been quantitatively investigated in this present paper. Isothermal compression experiment of Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy has been conducted for verification. Linear relationship between work-Hardening rate and true strain/stress has been derived from Kocks–Mecking dislocation relation. The work-Hardening Effect shows two obvious stages with strain: steady fluctuations and linear decreasing. Obvious work-Hardening Effect could be demonstrated under lower temperatures and higher strain rates. The work-Hardening decrease at linear-decreasing regime becomes more stronger with temperature elevated and rate lowered, reverse-proportional to Zener–Hollomon parameters. Strain-rate sensitivity coefficient for hot deformation was decomposed into three parts from JMAK recrystallization kinetics. The influence of strain rate on DRX evolution has been termed as the major factor determining strain-rate sensitivity. Strain-rate sensitivity coefficients for steady-state deformation ( ɛ = 0.7) of Ti–5Al–5Mo–5V–1Cr–1Fe alloy have been characterized as a function of deformation parameters and strain-rate sensitivity has been identified more obvious with temperature elevated and rate lowered.
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competition between work Hardening Effect and dynamic softening behavior for processing as cast gh4720li superalloys with original dendrite microstructure during moderate speed hot compression
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Yongquan Ning, T Wang, Lingshui Wang, Chen ZhaoAbstract:Abstract Competition between work-Hardening Effect and dynamic-softening behavior of as-cast GH4720Li superalloys with original dendrite microstructure during moderate-speed deformation was quantitatively investigated in this present paper. Flow behavior for processing the studied alloys with dendrite microstructure behaves typical three stages, caused by the competition Effect between work-Hardening and dynamic-softening. The relationships between work-Hardening rate and true strain and true stress were derived from Kocks–Mecking dislocation relation. The work-Hardening Effect shows two obvious stages with strain, viz. steady fluctuations and linear decreasing. An obvious work-Hardening Effect was demonstrated under lower temperature and higher strain rate. The linear relationship of work-Hardening rate θ on true stress e was constructed with the slope only related to annihilation coefficient Ω . The microstructural mechanism of as-cast GH4720Li superalloys during moderate-speed deformation was referred to dislocation multiplication and dendrite fragmentation, and the latter was beneficial to dynamic recrystallization during moderate-speed deformation.
Yang Nan - One of the best experts on this subject based on the ideXlab platform.
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work Hardening Effect and strain rate sensitivity behavior during hot deformation of ti 5al 5mo 5v 1cr 1fe alloy
Materials & Design, 2015Co-Authors: Yang Nan, Houquan Liang, Yongquan Ning, Hongzhen Guo, Zekun YaoAbstract:Abstract The work-Hardening Effect and strain-rate sensitivity behavior during hot deformation have been quantitatively investigated in this present paper. Isothermal compression experiment of Ti–5Al–5Mo–5V–1Cr–1Fe titanium alloy has been conducted for verification. Linear relationship between work-Hardening rate and true strain/stress has been derived from Kocks–Mecking dislocation relation. The work-Hardening Effect shows two obvious stages with strain: steady fluctuations and linear decreasing. Obvious work-Hardening Effect could be demonstrated under lower temperatures and higher strain rates. The work-Hardening decrease at linear-decreasing regime becomes more stronger with temperature elevated and rate lowered, reverse-proportional to Zener–Hollomon parameters. Strain-rate sensitivity coefficient for hot deformation was decomposed into three parts from JMAK recrystallization kinetics. The influence of strain rate on DRX evolution has been termed as the major factor determining strain-rate sensitivity. Strain-rate sensitivity coefficients for steady-state deformation ( ɛ = 0.7) of Ti–5Al–5Mo–5V–1Cr–1Fe alloy have been characterized as a function of deformation parameters and strain-rate sensitivity has been identified more obvious with temperature elevated and rate lowered.
Sunghak Lee - One of the best experts on this subject based on the ideXlab platform.
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Effects of microstructure and pipe forming strain on yield strength before and after spiral pipe forming of api x70 and x80 linepipe steel sheets
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Seok Su Sohn, Seung Youb Han, Jin Ho Bae, Hyoung Seop Kim, Sunghak LeeAbstract:Abstract API X70 and X80 linepipe steel sheets were shaped in the form of pipe with different strains (thickness/diameter ratio) by spiral pipe forming. Tension specimens taken from steel sheets or pipes at an interval of 2.5 mm were tested, and their yielding behavior, yield strength, and yield ratio before and after forming were analyzed. In the pipes, the continuous yielding and low yield ratios were shown in the inner side, whereas the discontinuous yielding and high yield ratios were shown in the outer side. This was because the Bauschinger Effect and the strain Hardening Effect were mainly dominant in the inner and outer sides, respectively. The overall yield strength after spiral piping was defined by the competing Effect of the strain Hardening and the Bauschinger Effect. The competing Effects depended on the microstructure and the pipe forming strains. The low-temperature transformation microstructures were preferred for achieving the larger increase of overall yield strength after pipe forming. For a specific microstructure an optimization of the yield strength can also be achieved by controlling the pipe forming strain in order to maximize the strain Hardening Effect and to minimize the Bauschinger Effect.
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Effects of microstructure and pre strain on bauschinger Effect in api x70 and x80 linepipe steels
Metals and Materials International, 2013Co-Authors: Seok Su Sohn, Seung Youb Han, Jin Ho Bae, Sang Yong Shin, Sunghak LeeAbstract:In this study, Effects of microstructure and pre-strain on the Bauschinger Effect were investigated in two API X70 and two API X80 linepipe steel sheets fabricated by controlling the cooling condition, and their yield strength and Bauschinger parameters were measured by the tension-compression test with varying tension pre-strain. The fast-cooled steels had the higher fraction of acicular ferrite, granular bainite and martensite-austenite (MA) constituents and smaller grain sizes. The reduction in yield stress (ΔYS) of the steels having a higher fraction of MA and smaller grain sizes was higher than that of the steels having a lower fraction of MA and larger grain sizes. The ΔYS was smallest at the pre-strain of 1%, reached the maximum at the pre-strain of 2%, and then decreased with increasing pre-strain. This result could be explained by the amounts of mobile dislocations and back stress, which affected the Bauschinger Effect and strain Hardening Effect simultaneously. Since these two Effects affected the yield strength on a competing basis, the Bauschinger stress and Hardening parameter were used to separately analyze these Effects. It could be confirmed that the Bauschinger Effect and strain Hardening Effect were activated at pre-strains of 1–2% and 3–4%, respectively.
