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6061铝合金搅拌摩擦焊接头组织与性能研究 总被引:1,自引:1,他引:0
采用搅拌摩擦焊方法(FSW)对6 mm厚的6061-T4铝合金板材进行对接,焊后利用光学显微镜(OM)和扫描电镜(SEM)分析、对比了焊接接头和母材的显微组织和断口形貌特征,并测试了其室温拉伸性能和显微硬度。实验结果表明:选择了适合于6061-T4铝合金板材搅拌摩擦焊的工艺参数:焊接时搅拌头旋转速度为1200 r.min-1,工件的进给速度为300 mm.min-1,在此参数下获得了与母材等强度、韧性接近于母材的焊接接头,为此种合金应用于汽车关键零部件提供了可靠的工艺方法。FSW板材接头焊核区的组织和性能明显优于其他区,热影响区是接头最薄弱的部分,焊核区的硬度最高,而热影响区的硬度最低,焊缝金属发生回复再结晶使晶粒细化。断口分析表明,断裂发生在热影响区,由于搅拌头的旋转运动和热量的累积,该区存在晶粒长大、组织粗化现象。对工艺参数的优化实验表明,搅拌头旋转速度与焊接速度对接头性能的影响存在一定的适配关系,通过工艺参数的调整可以有效地控制热影响区的焊缝组织和改善焊接接头的性能。细晶强化是搅拌摩擦焊接头强度与韧性提高的主要原因。 相似文献
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对3 mm厚6061-T6铝合金板材的搅拌摩擦焊工艺进行试验研究,分析了在搅拌摩擦焊焊接过程中不同搅拌头转速、焊接速度对焊接接头力学性能和焊缝中"S"线缺陷的影响。研究结果表明,当搅拌头转速保持在1 200 r·min~(-1)时,焊接工艺窗口较宽;当焊接速度为700 mm·min~(-1)、搅拌头的旋转速度为1 200 r·min~(-1)时焊缝的强度最高,为251.608 MPa,焊缝强度达到了母材的81.16%。焊接过程中提高搅拌头的旋转速度、减小焊接速度能够减少焊缝中"S"线缺陷的产生。 相似文献
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热挤压对喷射沉积7055铝合金显微组织和力学性能的影响 总被引:1,自引:0,他引:1
《粉末冶金材料科学与工程》2015,(5)
采用全自动控制往复喷射成形工艺制备工业规格7055铝合金锭坯,研究热挤压工艺对喷射成形7055铝合金的显微组织和力学性能的影响。采用电子背散射衍射技术对经不同热挤压后7055铝合金的织构进行研究。结果表明,喷射沉积锭坯组织为等轴状晶粒,均匀细小(30~50μm),基体中不存在枝晶型偏析。由于喷射沉积工艺本身的特点,在合金中存在大量的显微疏松缺陷。沉积锭坯经过热挤压致密化后,合金力学性能显著提高,抗拉强度σb为390 MPa,伸长率δ为13.3%,表明热挤压工艺可有效消除疏松缺陷,从而充分发挥出喷射沉积工艺的优越性。EBSD分析表明,挤压后沿着挤压轴方向形成丝织构,主要为?001?与?111?两种织构。 相似文献
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在ER5356铝合金焊丝中添加了微量的Sc、Zr和Er,制备出微合金化ER5356铝合金焊丝.使用微合金化焊丝焊接4 mm厚的5182铝合金板材,焊接采用手工钨极惰性气体保护焊.利用金相显微镜,X射线衍射以及透射电镜研究了微量的Sc、Zr和Er对5182铝合金焊缝处显微组织的影响.结果表明,在ER5356铝合金焊丝中添加的Sc、Zr和Er可以有效改善5182铝合金板材焊后焊缝处的显微组织,显著细化组织晶粒.其中,ER5356铝合金焊丝中单独添加0.3%Sc焊后效果最佳. 相似文献
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通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。 相似文献
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K Ohta M Nishi M Ueda S Ohyama T Matsubara T Takahashi T Nakajima 《Canadian Metallurgical Quarterly》1998,99(9):589-594
Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients. 相似文献
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Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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The rates of infection of two methods of external ventricular drainage in use at Atkinson Morley's Hospital--namely, (a) percutaneous drainage with Rickham reservoirs and (b) tunnelled ventriculostomies--were compared in this retrospective review. Percutaneous drainage of CSF with Rickham reservoirs was associated with a 27% rate of infection as identified by positive microbiological cultures; tunnelled ventriculostomy catheters had a 10% infection rate. The difference in the infection rate between the two methods was statistically significant (P < 0.015). Other variables examined, including the age and sex of the patients and the reasons for ventricular drainage, were not associated with an increased rate of infection. Most infections from either method were caused by a coagulase negative staphylococcus. The average duration of ventricular drainage before identification of positive cultures was 5.7 days for Rickham reservoirs and 6.0 days for ventriculostomies. 相似文献
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鲁迅先生一生热爱美术作品,对版画中木刻兴趣尤甚.<野草>作为其"写心之作",亦呈现出一些与木刻版画一致的审美特征:一是具有木刻版画的色彩特征,多对比、多冷色,有阴郁的美感;二是具有木刻版画的力度特征,环境描写、人物刻画处处刀锋毕现,遒劲有力,有一种"力之美". 相似文献
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针对四辊破碎机车刀架车削中存在的几个问题,详细介绍了电动车刀架的结构和工作原理,建立主要设计参数的数学表达式,并进行适当的分析。改造后,这种电动车刀架运行平稳、可靠、方便、省力,取得了预期的效果。 相似文献
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The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed. 相似文献