Y. H. Li
,
M. Krzyzanowski
,
J. H. Beynon and C. M. Sellars IMMPETUS( Institute for Microstructural and Mechanical Process Engineering: The University of Sheffield
,
Sheffield SI 3JD
,
UK)
金属学报(英文版)
In the last few years,substantial experimental simulation and mumerical modelling hare been carried out in IMMPETUS to characterise the interfacial heat transfer and friction conditions during hot forging and rolling of steels. Emphasis has been placed on the influence of the oxide scale which forms on the steel workpiece. In the present paper, the experimental methods used for investigating interfacial heat transfer and friction conditions are described. Theses include hot flat rolling of steel slabs and hot axi- symmetric forging of steel cylinders and rings.Temperature measurements and computations demon- strate that for similar conditions, similar conditions, the effective interfacial heat transfer coefficients (IHTC) derived for hot rolling are significantly higher than those for forging, mainly due to the contribution of scale cracking during rolling. On the basis of experimental observations and numerical analysis,physical models for interfacial heat transfer in forging and rolling have been established. In addition, hot" sandwich" rolling and hot tensile tests with finite element modelling have been carried out to evaluate the hot ductility of the oxide scale.The results indicate that the defomation, cracking and decohesion behaviour of the oxide scale depend on deformation temperature, strain and relative strengths of the scale layer and scale - steel interface.Finaly, friction results from hot ring compression tests and from hot rolling with forward/backward slip measurements are reported.
关键词:
interfacial heat transfer
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null
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null
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null
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null
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null
李轶
,
李慧中
,
姜俊
,
欧阳杰
航空材料学报
doi:10.11868/j.issn.1005-5053.2014.6.004
通过对AZ80镁合金进行总应变幅控制下的室温低周疲劳实验,研究其在热锻、时效态(T5)、固溶时效态(T6)三种不同热处理状态下的循环应力响应、疲劳寿命和循环应力-应变行为.结果表明:在三种不同的热处理制度下,AZ80镁合金大体上都表现为循环应变硬化现象;此外,AZ80镁合金的应变疲劳寿命与塑性应变幅、弹性应变幅之间的关系分别服从Coffin-Manson和Basquin关系式.随着外加总应变幅的不断增大,其疲劳寿命减少.在0.3％的最小外加总应变幅下,AZ80热锻态的疲劳寿命最长;在0.9％的最大外加总应变幅下,AZ80-T5的疲劳寿命最长,而热锻态最短.此外,对疲劳断口形貌的观察结果表明,疲劳裂纹萌生于疲劳试样表面,并以穿晶方式扩展.
关键词:
热处理
,
热锻
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循环应力响应
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低周疲劳
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疲劳寿命
白倩
,
林建国
航空材料学报
doi:10.11868/j.issn.1005-5053.2014.4.006
钛合金广泛用于制造航空发动机叶片,高温锻造是制造钛合金发动机叶片的主要热加工工艺之一.钛合金叶片高温锻造研究中,有限元模拟是分析锻造过程中的热力耦合,预测并优化锻造成形过程的一个重要手段.回顾有限元建模在涡轮叶片锻造研究中的发展历程,概述材料本构模型、传热定义和摩擦特性等方面的研究,以确保有限元模型有效预测的因素.分析表明,为获得精确可靠的有限元模拟结果进而优化生产工艺,有限元模型需要基于合理的试验结果并确立可预测的物理模型.
关键词:
钛合金
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发动机叶片
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高温锻造
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有限元建模
陈瑜
,
王建忠
,
李娜
,
祁立国
,
张浩
物理测试
针对45圆钢热顶锻开裂问题，从宏观和微观两方面对裂纹原因进行分析，结果表明圆钢折叠缺陷是引起热顶锻裂纹的主要原因，同时局部脱碳加剧了顶锻开裂。可以通过严格执行检修和轧制制度，同时配合优化轧钢加热制度来消除热顶锻裂纹的发生。
关键词:
45圆钢
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热顶锻
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折叠
