金属材料淬火过程中温度参数相关试验的研究进展

淬火工艺是金属零件生产加工过程中不可缺少的关键环节,而温度是淬火过程控制的关键要素.围绕金属材料淬火过程中的温度及其相关参数,对工件表面温度、工件与冷却介质间的传热,以及冷却介质的流动和沸腾的试验研究进行了总结与分析.提出今后与淬火温度参数相关的试验研究,应以进一步提高温度测量精度、优化分析方法为方向.     

实时测温技术在调质热处理中的应用

热处理工艺参数对金属部件的组织和力学性能有显著的影响,以盘形工件淬火热处理为例,采用实时测温技术准确监控淬火热处理过程中工件的加热和冷却的温度一时间历程,并结合随炉试样的组织和力学性能,科学制定出热处理工艺规范,控制热处理工艺过程,稳定热处理质量,使工件性能满足了使用要求.     

表面换热系数对铝厚板淬火温度和应力演变影响的数值模拟

淬火过程中表面换热系数是反映界面能量传递和介质冷却能力的重要物理参数。通过对铝厚板淬火的多组模拟实验，研究了表面换热系数对工件冷却速度、内应力演变的影响规律。结果表明，过大的表面换热系数并不能明显提高工件心部的冷却速度．却大大增加了工件的残余应力。铝厚板淬火工艺应用据工件的组织性能要求，合理选择的表面换热系数和冷却方式，尽量减小工件的残余应力。     

工件的淬火变形机理及预防和矫直措施

因淬火过程中的快速冷却而在工件内部产生的内应力是导致淬火变形的根本原因。对影响工件淬火变形的主要因素进行了探讨，提出了相应的预防和矫直措施，为降低生产成本提供了一定的参考。     

轧机衬板激光淬火工艺优化及变形的消除

激光表面淬火是激光表面改性领域中最先进的技术，它利用金属良好的导热性，将高能激光束照射到工件表面，使表层温度迅速升高至相变点之上(低于熔点),当激光束移开后，工件快速地自然冷却，实现材料的相变硬化。介绍了轧机衬板激光淬火的工艺特点，研究了激光表面淬火工艺参数对工件组织及性能的影响，确定了满足轧机衬板硬度和安装精度的工艺参数：激光功率1 600～1 700 W,扫描速度8～10 mm/s,光斑宽度15～17 mm。通过分析淬火后工件变形的原因，提出可利用专用加热设备使工件产生反向预变形，消除因激光淬火残余压应力产生的平面度变形。     

淬火温度对51CrV4弹簧钢组织及性能的影响

研究了51CrV4弹簧钢生产流程中,在相同的均温炉热处理后,工件进入淬火油前的实际温度(淬火温度)对弹簧钢组织及性能的影响。研究结果显示:淬火温度是决定弹簧钢组织及性能的关键因素之一;淬火温度的提升,有助于提高弹簧钢的塑性和延展性,但相应地降低了弹簧钢的强度和硬度。在实际生产中,应根据对产品性能的要求,严格控制淬火温度参数,提高产品性能的一致性。     

GH4169合金淬火残余应力的中子衍射及有限元分析

淬火工艺是工件制作过程中不可或缺的环节,而温度梯度又会导致残余应力的产生,因此准确表征GH4169工件内部残余应力及探索建立有效的有限元模拟分析对了解和改善其性能具有重要意义。利用中子衍射的手段研究了GH4169合金淬火残余应力分布,并对淬火过程的温度场和应力场进行有限元数值模拟分析。结果表明:淬火后工件中心的残余应力状态为3向拉应力,约为400MPa;工件近表层形成单向或双向压应力状态,约-300~-400MPa。将有限元计算得到的试样中心和表面处的残余应力和应变与中子衍射测试结果进行对比,结果表明二者应力分布规律较为一致。结合中子衍射和有限元模拟的结果,较为合理地阐述了快速冷却过程中残余应力的形成机制。     

深井式淬火水槽水循环方式对硬度的影响

介绍了为长轴类工件淬火的深井式淬火设备,通过对3个试验结果的分析,探讨了深井式淬火水槽水循环方式对长轴类工件表面硬度的影响因素。     

汽车轮毂单元总成65Mn钢轴系工件断裂分析

采用扫描电子显微分析、金相组织分析等方法,对汽车后轮毂单元总成65Mn钢轴系工件在汽车行驶过程中发生断裂的原因进行了分析。结果表明,该工件在表面高频淬火过程中局部产生过热和过烧组织是汽车在行驶过程中轴系工件发生断裂的主要原因。     

铝合金淬火炉设计与应用

目前,在我国机械行业专门用于铝合金淬火的炉子还不太多,但是需要进行热处理的各种各样的铸锻铝合金工件却是大量的。由于铝合金具有不同于一般黑色金属的特性,如:对加热温度要求准确而且均匀,对需进行淬火处理的工件要求转移速度快。另外,由于铸锻铝合金的淬火温度与其熔点温度(658℃)很接近,故在加热过程中必须有可靠的控温手段,不能使被加热的工件出现过烧现象。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

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)     

Comparison of rates of infection of two methods of emergency ventricular drainage

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.     

浅析《野草》的版画特征

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".     

四辊破碎机车刀架的改造

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。     

Results of treatment of cancer of the cardia

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.     

焦炭热性能指标意义浅析

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。     

Comparison of the results of surgical and conservative treatment of fractures of the diaphysis of the tibia

In this paper is treated the fundamental problematic of the fracture of the diaphysis of the tibia and the therapeutic results after the conservative and operative treatment are confronted. Among 518 patients with 433 open fractures and 35 with closed fractures of the diaphysis of the tibia, successful treatment of more 2/3 was obtained in the period from 1968 to 1972. Following our casuistics and literature, whose results are similar, we find out that the average total treatment of the osteosynthesis of the fracture of the diaphysis was shortened for 2,5 months depending upon the type and the localisation of the fracture. Apolied methods of the operative and conservative and conservative treatment in relation to the velocity of the medical cure as well as to the extreme anatomical-functional results are analised. We noticed that osteosynthesis, made by the intermedullary nail and the extension of the canals or by a small AO table, by the achieved stability makes conditions of immediate motions and an early rehabilitation. Because of that it gives the best functional results.