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等径弯曲通道变形对超低碳钢组织及性能的影响 总被引:1,自引:0,他引:1
研究了室温下C方式等径弯曲通道变形(ECAP)对超低碳钢组织及性能的影响。结果表明:第1道次ECAP变形后,组织细化效果最显著;随变形道次的增加,组织由取向差小的板条状亚晶演变成取向差大的等轴晶;第4道次ECAP变形后,晶粒平均尺寸约03 μm;变形道次继续增加,晶粒尺寸变化不显著,而晶粒取向差不断增大。这表明第4道次ECAP变形为超低碳钢细化极限;ECAP变形可大幅度提高超低碳钢的强度,并保持较高的塑性。 相似文献
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镁及镁合金属于HCP结构,织构和晶粒尺寸是影响其性能的主要因素.本文对近年来镁及镁合金等通道转角挤压(Equal channel angular pressing,ECAP)的研究状况进行了综述,介绍了ECAP过程中影响镁及镁合金织构的主要因素.根据晶粒细化机制的不同,从两方面介绍了ECAP工艺制备镁及镁合金超细晶、纳... 相似文献
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热加工对铸造AM50镁合金显微结构和力学性能的影响 总被引:4,自引:0,他引:4
采用锻造和等通道转角挤压(ECAP)等技术研究了热加工对铸造AM50镁合金显微结构和力学性能的影响, 以改善该合金的力学性能.结果发现, ECAP对铸造AM50镁合金和锻造AM50镁合金两种显微结构的影响不同, 这是由于两种状态初始晶粒尺寸不同引起的.铸态AM50镁合金晶粒尺寸粗大, 经过ECAP工艺后, 晶界上出现大量平直滑移线;而锻态AM50镁合金经过ECAP工艺后, 晶粒进一步细化, 滑移线痕迹不明显.铸态AM50镁合金经过ECAP工艺后显微硬度从54.5提高到72.3, 锻造AM50镁合金经过ECAP工艺后显微硬度从60.3提高到81.9.铸造AM50镁合金经过锻造及ECAP工艺热加工后力学性能抗拉强度提高到320 Mpa, 同时延伸率保持在35%以上. 相似文献
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采用刚粘塑性有限元软件对ZK60合金四道次等通道转角挤压(ECAP)过程进行数值模拟。对一至四道次ECAP试样进行晶粒组织模拟,观察晶粒细化程度的分布和变化规律。通过多道次ECAP实验,利用金相显微观察试样头部和尾部的晶粒尺寸的变化以及动态再结晶形成机理。对比有限元数值模拟与实验组织分析结果,探索利用有限元模拟与实验分析相结合的方法,研究镁合金ECAP成形过程的晶粒组织变化规律。 相似文献
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《稀有金属》2019,(8)
室温下具有密排六方(hcp)晶体结构的钛,由于在晶体学上具有较低的对称性,只有4个独立滑移系,塑性变形能力差。工业纯钛的塑性变形机制主要为滑移和孪生,且孪生变形在塑性变形过程中起着重要的作用,显著地影响工业纯钛的显微组织及力学性能。等径弯曲通道变形(equal channel angular pressing, ECAP)是最具有工业应用前景的剧烈塑性变形技术之一,成功制备性能优异的超细晶(UFG)工业纯钛。本文综述了工业纯钛ECAP变形过程中的孪生行为及机制研究进展。重点从ECAP变形工艺:挤压温度、挤压道次、挤压速度、模具参数以及晶粒尺寸等方面详细论述了工业纯钛ECAP变形过程中的孪生行为,分析了工业纯钛ECAP变形过程中不同阶段的孪生机制,并指出工业纯钛ECAP变形过程中的孪生行为及机制研究中存在的问题及今后的研究方向。 相似文献
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Zhi Chao Duan Nguyen Q. Chinh Cheng Xu Terence G. Langdon 《Metallurgical and Materials Transactions A》2010,41(4):802-809
The processing of age-hardenable aluminum alloys by equal-channel angular pressing (ECAP) was investigated using three different
Al-Zn-Mg alloys. The results show that it is relatively easy to conduct the ECAP at an elevated temperature of 473 K, but
this leads to a weakening of the alloy rather than a strengthening. The processing by ECAP may be performed successfully at
room temperature provided it is conducted fairly quickly (within ~10 minutes) after quenching from the solution treatment.
It is necessary also to optimize the solution treatment conditions for each alloy composition. Under optimum conditions, good
strengthening is achieved even after a single pass in ECAP. 相似文献
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G. K. Manjunath K. Udaya Bhat G. V. Preetham Kumar M. R. Ramesh 《Transactions of the Indian Institute of Metals》2018,71(8):1919-1931
In the present investigation, wear performance of equal channel angular pressing (ECAP) processed cast Al–Zn–Mg alloys under dry sliding wear conditions was studied against a steel disc. Initially, Al–Zn–Mg alloys (with 5, 10, 15% zinc and 2% magnesium) were ECAP processed. After ECAP, grain size was reduced and enhancement in the hardness was observed. Wear resistance of the alloys increased after ECAP processing. Wear resistance of the alloys also increased when the quantity of the zinc was increased in the alloys. But, wear resistance of all three alloys decreased with increase in the load and the sliding speed. Coefficient of friction of the alloys decreased after ECAP processing. Coefficient of friction of the alloys also decreased when the quantity of the zinc was increased in the alloys. Coefficient of friction of all three alloys increased with increase in the load and the sliding speed. Irrespective of the alloy composition and applied load, worn surfaces of the cast and homogenized samples were composed of plastic deformation, scratches and micro-ploughing. On the other hand, in ECAP processed samples, morphology of the worn surfaces depended on the applied load. Abrasive wear is the main wear mechanism perceived in cast and homogenized samples at all loads. While in ECAP processed samples, the wear mechanism shifted from adhesive and oxidation wear to abrasive wear with increase in the load. Formation of oxide layers on the surface of the sample increased with increase in the ECAP passes. In ECAP processed samples, transfer of iron content from the disc to the sample surface was identified. 相似文献
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Zuogui Zhang Yoshimi Watanabe Icksoo Kim Xiangfa Liu Xiufang Bian 《Metallurgical and Materials Transactions A》2005,36(3):837-844
Refining experiments were conducted to evaluate the grain refining performance of an Al-5Ti-0.25C refiner before and after
equal-channel angular pressing (ECAP) with the use of a high-purity Al. The results show that the Al-5Ti-0.25C refiner has
remarkable and stable grain refining performance when the holding times are within 5 to 30 minutes and the melt temperatures
are within 1003 to 1073 K. Furthermore, some Al-5Ti-0.25C refiner samples were subjected to severe plastic deformation by
using the ECAP technique at 298 K. It was found that Al3Ti and TiC particles were significantly fragmented and their mean sizes were decreased to 10 and 1.08 μm, respectively, and the Al-5Ti-0.25C refiner appeared to have a double grain refining effect in comparison with that of before
ECAP. It is also testified that the Vickers microhardness (Hv) value of the pure Al samples refined by the Al-5Ti-0.25C refiner
after ECAP processing has a significant increment than that of before ECAP processing. It is concluded that the Al-5Ti-0.25C
refiner with ECAP technique has a very useful practical application in refining industrial Al alloys. 相似文献
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Zuogui Zhang Yoshimi Watanabe Icksoo Kim Xiangfa Liu 《Metallurgical and Materials Transactions A》2005,36(13):837-844
Refining experiments were conducted to evaluate the grain refining performance of an Al−5Ti−0.25C refiner before and after
equal-channel angular pressing (ECAP) with the use of a high-purity Al. The results show that the Al−5Ti−0.25C refiner has
remarkable and stable grain refining performance when the holding times are within 5 to 30 minutes and the melt temperatures
are within 1003 to 1073 K. Furthermore, some Al−5Ti−0.25C refiner samples were subjected to severe plastic deformation by
using the ECAP technique at 298 K. It was found that Al3Ti and TiC particles were significantly fragmented and their mean sizes were decreased to 10 and 1.08 μm, respectively, and
the Al−5Ti−0.25C refiner appeared to have a double grain refining effect in comparison with that of before ECAP. It is also
testified that the Vickers microhardness (Hv) value of the pure Al samples refined by the Al−5Ti−0.25C refiner after ECAP
processing has a significant increment than that of before ECAP processing. It is concluded that the Al−5Ti−0.25C refiner
with ECAP technique has a very useful practical application in refining industrial Al alloys.
ZUOGUI ZHANG, formerly Master's Student, the Key Laboratory of Liquid Structure and Heredity of Material, Ministry of Education,
Shandong University, Jinan 250061, People's Republic of China 相似文献
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Kiyoshi Matsubara Yuichi Miyahara Zenji Horita Terence G. Langdon 《Metallurgical and Materials Transactions A》2004,35(6):1735-1744
Experiments were conducted to evaluate the utility of a new processing procedure developed for Mg-based alloys in which samples
are subjected to a two-step processing route of extrusion followed by equal-channel angular pressing (designated as EX-ECAP).
The experiments were conducted using a Mg-0.6 wt pct Zr alloy and, for comparison purposes, samples of pure Mg. It is shown
that the potential for successfully using ECAP increases in both materials when adopting the EX-ECAP procedure. For the Mg-Zr
alloy, the use of EX-ECAP produces a grain size of ∼1.4 μm when the pressing is undertaken at 573 K. By contrast, using EX-ECAP with pure Mg at 573 K produces a grain size of ∼26
μm. Tensile testing of the Mg-Zr alloy at 523 and 573 K after processing by EX-ECAP revealed the occurrence of significantly
enhanced ductilities with maximum elongations of ∼300 to 400 pct. 相似文献
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Megumi Kawasaki 《Metallurgical and Materials Transactions A》2011,42(10):3035-3045
Processing through the application of severe plastic deformation (SPD) has become an absorbing tool because it provides the
potential for refining the grain size of polycrystalline bulk metals to the submicrometer or even the nanometer level. Several
SPD methods are now available, but the more promising procedures seem to be equal-channel angular pressing (ECAP) and high-pressure
torsion (HPT). This report examines these procedures with an emphasis on the principles of grain refinement and the mechanical
properties developed at high temperatures in materials after processing by ECAP and the hardness homogeneity and microstructural
evolution in materials processed by HPT. Moreover, recent observations on the ECAP and HPT processing also are discussed. 相似文献
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Ruslan Z. Valiev Terence G. Langdon 《Metallurgical and Materials Transactions A》2011,42(10):2942-2951
The processes of equal-channel angular pressing (ECAP) and high-pressure torsion (HPT) are now established for the fabrication
of ultrafine-grained metals having superior properties by comparison with their coarse-grained counterparts. This article
examines the recent developments designed to improve the processing technology of ECAP and HPT and to establish these techniques
as viable procedures for use in industrial applications. Based on these developments, it is reasonable to anticipate these
processing procedures will experience increasing use in the fabrication of commercial products. 相似文献
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Maddela Sudhakara Rao Uday Chakkingal Thatikonda Raghu 《Transactions of the Indian Institute of Metals》2013,66(4):357-362
Equal channel angular pressing (ECAP) has been widely shown to be able to produce ultrafine grained microstructures in a variety of metals and alloys. In this study, the ECAP process has been used as an intermediate processing step prior to cold rolling to achieve superior mechanical properties. Commercial purity (CP) titanium was processed by ECAP at 400 °C and subsequently the ECAPed specimens were subjected to a post deformation process by conventional cold rolling. Microstructure and mechanical property characterization of CP titanium billets subjected to ECAP alone and ECAP plus cold rolling were carried out. 98 % reduction in thickness (from 15 to 0.2 mm thickness) was possible by cold rolling. Post-deformation by cold rolling significantly increased the strength of CP titanium while retaining considerable ductility. TEM images after ECAP show deformation induced dislocation networks and the disintegration of the initial coarse grained microstructure giving rise to lamellar structures 0.3–0.5 μm in width. 相似文献