Kehai Li
材料科学技术（英）
Modification of conventional gas metal arc welding (GMAW) process is of great potential to achieve high productivity with low cost and strong usability. Double-Electrode GMAW (DE-GMAW) is such a modified arc welding process which is formed by adding a bypass torch (gas tungsten arc welding torch) to a conventional GMAW system. The mechanism of metal transfer in DE-GMAW was proposed and verified in this paper. Experiments show that the critical current is decreased so that spray transfer can be obtained at a lower current level in DE-GMAW. Analysis of this significant change in metal transfer phenomena is conducted, and explanation is given out. It is found that the bypass arc in DE-GMAW lifts the anode point on the droplets such that the electromagnetic force becomes larger and squeezes the droplets so that spray transfer can take
place under welding current lower than that in conventional GMAW.
关键词:
Metal transfer
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null
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null
张麦仓
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董建新
,
曾燕屏
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谢锡善
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罗子健
金属学报
利用热力耦合有限元程序FORMT,对PM René 95合金中等尺寸(外径尺寸约为630 mm)涡轮盘的等温锻造工艺进行了模拟式设计.结果表明,采用TZM钼基合金模具,在1050℃以接近10-3s.的应变速率进行闭式模锻和开式模锻,模具材料均能满足使用要求,且开式模锻设备最大载荷不超过31×103kN;采用K21合金模具,在1000℃以相同条件等温成形,模具材料因变形热效应及边界摩擦引起温升而失效且所需设备吨位相对较大.
关键词:
PM
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null
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null
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null
张麦仓
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董建新
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曾燕屏
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谢锡善
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罗子健
金属学报
doi:10.3321/j.issn:0412-1961.2002.10.022
利用热力耦合有限元程序FORMT,对PM René 95合金中等尺寸(外径尺寸约为630 mm)涡轮盘的等温锻造工艺进行了模拟式设计.结果表明,采用TZM钼基合金模具,在1050℃以接近10-3s.的应变速率进行闭式模锻和开式模锻,模具材料均能满足使用要求,且开式模锻设备最大载荷不超过31×103kN;采用K21合金模具,在1000℃以相同条件等温成形,模具材料因变形热效应及边界摩擦引起温升而失效且所需设备吨位相对较大.
关键词:
PM René 95合金,等温锻造,热力耦合有限元,模拟式工艺设计
Materials Letters
Highly preferred (002) orientation transparent conductive Al-doped ZnO (ZAO) films were successfully prepared by de magnetron reactive sputtering from a Zn target mixed with Al of 2.0 wt.%. The film has a resistivity of 4.80 X 10(-4) n cm and a visible transmittance of as high as 90%. XPS analysis indicates Al-enrichment on the film surface. The asymmetry of Al 2p(3/2) XPS peak is resolved into two components: one centering at 72.14 eV attributed to metallic Al and the other having a binding energy of 74.17 eV due to oxidized Al. (C) 2001 Elsevier Science B.V. All rights reserved.
关键词:
Al-doped;ZnO;XPS;Al-enrichment;oxide thin-films;optical-properties;electrical-properties;rf;dc;transparent;deposition
付锐
,
陈希春
,
任昊
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冯涤
航空材料学报
doi:10.3969/j.issn.1005-5053.2011.3.002
自行设计开发了适合工业化生产高纯净,低偏析,无宏观缺陷铸锭的电渣重熔连续定向凝固技术(ESR-CDS)的设备和工艺,利用该技术成功制备了直径为φ150mm的René88DT合金定向凝周铸锭.采用XRD测试了定向凝固柱状晶的生长取向,结果表明,ESR-CDS René88DT铸锭柱状晶择优生长方向为<100>系晶向;ERS-CDS铸锭与传统ESR铸锭相比,枝晶组织生长方向保持一致,二次枝晶臂均匀细小,元素偏析程度低,且晶间一次析出相呈颗粒状,尺寸细小;等温热压缩实验结果表明,ESR-CDS René88DT合金热压缩试样在1100℃,0.0-50.1s-1应变速率下可达到70%以上压缩变形量并获得均匀细小的动态再结晶组织;ESR-CDS René88DT合金铸锭经等温锻造制备出了φ170mm×73mm的饼坯件,锻压变形量超过70%,饼坯件除上下两端的变形死区外均发生了动态再结晶,晶粒尺寸约50μm.
关键词:
电渣重熔连续定向凝固
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热变形
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动态再结晶
武传松
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张明贤
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李克海
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张裕明
金属学报
doi:10.3321/j.issn:0412-1961.2007.06.021
通过大量的工艺实验,找出了DE-GMAW双焊枪组合的匹配参数,测试了焊接电流波形,拍摄了熔滴过渡图像,并获得了无成型缺陷的焊缝照片.基于实验结果解释了高速焊接工艺的机理.建立了适用于DE-GMAW焊接工艺的有限元模型,并对该工艺条件下的温度场、应力-应变场进行了数值模拟.结果表明:计算出的DE-GMAW焊缝横断面形状尺寸与实验结果吻合良好;在通过焊丝的总电流相同时,DE-GMAW焊接时焊缝尺寸、热影响区宽度、应力、应变及变形均小于常规GMAW焊时的结果.这为DE-GMAW焊接工艺参数优化提供了基础数据.
关键词:
高速电弧焊接
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工艺机理
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DE-GMAW
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有限元分析
李晓
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董建新
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张丽娜
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张麦仓
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胡尧和
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谢锡善
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国为民
金属学报
经不同固溶时效处理的PM René 95合金于650℃分别在蠕变、保载5和90 s疲劳载荷条件下进行了裂纹扩展速率实验.结果表明,相同热处理制度下,疲劳保载时间越长,裂纹扩展速率越高;相同载荷条件下,增加一次高温固溶并缓冷,有利于降低合金的裂纹扩展速率,且固溶温度越高裂纹扩展速率越低;1200℃一次固溶缓冷并于1160℃二次固溶热处理比1140℃一次固溶的裂纹扩展速率约降低一个数量级;基体晶粒尺寸适当加大,强化相粒子γ′c数量增加、形状趋于田字形,有利于降低裂纹扩展速率.
关键词:
René
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null
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null
