风电用渗碳齿轮钢17CrNiMo6的生产实践

介绍了莱钢利用100 t电炉短流程生产线开发生产风电用渗碳齿轮钢17CrNiMo6的工艺和产品性能,结果表明,钢的生产工艺设计合理,产品质量稳定,低倍、力学性能、淬透性、非金属夹杂物、显微组织、晶粒度及表面质量满足了标准及用户要求。     

基于DEFORM-3D的2024铝合金锻造变形过程晶粒度分析

本文采用了DEFORM-3D仿真模拟软件对2024硬铝材质的直齿圆锥齿轮进行锻造过程模拟仿真。通过仿真后处理对比分析了锻造工艺过程中齿轮锻微观组织的晶粒度演变规律及其晶粒度等级的影响因素,有利于直齿圆锥齿轮综合力学性能的优化。     

风电齿轮箱金属齿轮轴断齿失效分析

应用体视显微镜、金相显微镜、扫描电镜、冲击试验机、硬度计、电感耦合等离子发射光谱仪等通过宏观检查、断口形貌分析、化学成分分析、力学性能试验、金属夹渣物评级等方法对某风电齿轮箱金属齿轴断齿现象进行分析。分析结果表明金属齿轮表面淬硬处理后表面有微裂纹存在,轮齿承载后齿根附近受到的应力较大,在交变应力的作用下轮齿发生了疲劳折断。     

二联齿轮断齿分析

通过化学分析、力学性能测试、金相和断口分析,对二联齿轮失效原因进行综合分析。结果表明,主要是由于加工质量较差、原材料不合格和热处理不当等引起的疲劳断裂。     

扇形齿轮开齿调质工艺研制

介绍了扇形齿轮经开齿后调质的一种工艺方法,调质时采取新型的防变形工装制具,减小了扇形齿轮开齿后调质的变形,保证了扇形齿轮的齿面硬度均匀,基体具有良好的综合力学性能,同时又满足了精加工的要求及精度。     

螺旋齿轮与正齿轮的表面致密化

过去几十年,用于汽车的粉末冶金零件不断增长,对零件性能的要求也越来越高.汽车用的变速器齿轮的形状复杂,按照齿轮质量要求(DIN,ISO,AGMA等)几何精度很高,按齿面与齿根的耐久性要求力学性能也很高.对于制造复杂形状零件,粉末冶金法对控制成本很有效.通过增加对齿的选择性致密化,在增加很少费用下就能满足精度与力学性能要求.由压制、烧结、碾压致密化及最后热处理组成的工艺路线,可评估用粉末冶金制造的变速器齿轮的可行性.在研究中所用的螺旋齿轮与正齿轮,对致密化及所得到的齿轮的质量与齿根疲劳都进行了试验.     

正火工艺对S275NL风电用钢组织和性能的影响

采用光学显微镜和力学性能测试设备研究了不同正火工艺对S275NL高韧性风电用钢组织和性能的影响。试验结果表明,随着正火温度的提高,钢板强度有所降低,伸长率和Z向性能逐步提高,低温冲击韧性得到改善;正火保温时间对力学性能的影响不显著。适宜的正火加热温度为900℃,保温时间175 min,该工艺处理后,钢板组织为细小均匀的铁素体和珠光体,钢板强度富余量合理,强韧性匹配和综合力学性能良好。     

20CrMnTiH齿轮钢产品质量及控制技术研究

对国内多个优特钢企业生产的20CrMnTiH齿轮钢取样检验,对比分析化学成分、力学性能、高低倍组织等实物水平,结合检验结果和齿轮钢的发展状况,分析生产20CrMnTiH齿轮钢的控制关键点,形成开发前期的技术研究储备。     

铸坯碳偏析对Q345E低温冲击性能的影响

 为了适应风电法兰恶劣的工作环境,提高使用寿命,对风电法兰用钢Q345E低温冲击性能提出了在－50 ℃测试的要求,而且内外部性能要求均匀一致。为了提高Q345E钢的心部力学性能, 采用不同连铸工艺生产了具有不同凝固组织的圆坯, 分析了铸坯碳偏析对力学性能的影响,为改善Q345E钢心部的力学性能提供了依据。结果表明, 提高铸坯等轴晶率和细化凝固组织可降低铸坯心部的碳偏析程度,能显著提高钢材内部力学性能的均匀性。     

摩托车零件用GL—90粉末冶金钢的研制与应用

测定了高强度可热处理粉末冶金钢GL-90的力学性能、显微组织与密度、回火温度的关系。密度大于6.90g/cm~3的粉末冶金钢在可控气氛下淬火、低温回火后,组织为细束板条马氏体,具有最佳的综合力学性能。其性能与日本高强度热处理粉末冶金钢H-90相仿,抗拉强度达890 MPa,耐磨性能优于45~#钢。已成功地用GL-90粉末冶金钢制成全城摩托车传动轴内、外套异形齿轮。     

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。     

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。     

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.     

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。     

Effect of antibiotics of chemotaxis of human leukocytes

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.