热处理状态对6061铝合金应力腐蚀性能的影响

以6061铝合金为研究对象,通过慢应变速率拉伸(SSRT)、断口扫描和金相组织分析等方法,研究了不同热处理状态包括铸态、均匀化态、热轧态和T6峰时效态的应力腐蚀性能。结果表明:6061铝合金从铸态、均匀化态、热轧态到T6峰时效态,均不存在应力腐蚀性能上的"遗传性"。另外,除了热轧态的合金不具有应力腐蚀敏感性外,其余3种状态下,6061铝合金的应力腐蚀敏感性情况为:均匀化态铸态T6峰时效态,其应力腐蚀敏感性系数分别为0.094、0.064、0.053。     

时效制度对7B04高强铝合金力学及腐蚀性能的影响

采用常规力学性能、标准紧凑拉伸、电导率、慢应变速率拉伸(SSRT)及剥落腐蚀测试等手段,研究了不同热处理状态下7B04铝合金预拉伸板的力学及腐蚀性能。结果表明,合金的强度、韧性和腐蚀性能与时效制度密切相关。单级峰时效(T6)状态下合金的强度最高,但是其抗应力腐蚀(SCC)性能及断裂韧性最低;双级过时效(T74和T73)状态下材料的断裂韧性和抗SCC性能明显提高,但是其强度牺牲较多;与T6相比,RRA时效处理可明显提高合金的抗SCC性能,且强度牺牲较少,仅下降2%左右,同时断裂韧性也有一定提高。     

预拉伸变形对Al-Cu-Mg合金腐蚀性能的影响

采用表面腐蚀、慢应变速率拉伸(SSRT)实验研究预拉伸变形对Al-Cu-Mg合金腐蚀性能的影响。利用扫描电镜观察分析Al-Cu-Mg合金断口形貌及结构。结果表明,预拉伸变形可显著提高合金位错密度,为H原子的扩散提供更多的通道,因此,在相同腐蚀时间下,3.5%NaCl溶液中T8态Al-Cu-Mg合金的腐蚀速率高于T6态。此外,预拉伸变形可显著增加S相弥散度,使得S相两侧的无沉淀析出带变窄,有效降低了晶界和晶内的电位差,从而降低晶界沉淀相的溶解速度,因此,在同一热处理状态下,Al-Cu-Mg合金在饱和H2S溶液中的应力腐蚀开裂敏感性高于干燥空气中的腐蚀开裂敏感性。同一应变速率下,T8态Al-Cu-Mg合金具有比T6态更好的抗应力腐蚀性能,表明预拉伸变形处理可显著提高合金的抗应力腐蚀性能。     

1420合金的应力腐蚀断裂行为

采用电化学方法和慢应变速率拉伸(SSRT)技术，研究了时效制度对1420Al-Li合金的时效动力学及抗应力腐蚀性能的影响。通过透射电镜、扫描电镜观察与分析，探讨了不同时效处理工艺下1420合金的显微组织、慢应变速率拉伸断口形貌及其影响机制。结果表明，与120℃／12h相比，采用120℃，6h 190℃，6h处理不仅可以缩短合金到达时效峰值的时间，提高合金的强度，使其断裂强度、断裂时间、延伸率以及总断裂能等都得到显著提高，同时也改善了合金的抗应力腐蚀性能。     

时效制度对7804高强铝合金力学及腐蚀性能的影响

采用常规力学性能、标准紧凑拉伸、电导率、慢应变速率拉伸（SSRT）及剥落腐蚀测试等手段,研究了不同热处理状态下7804铝合金预拉伸板的力学及腐蚀性能。结果表明,合金的强度、韧性和腐蚀性能与时效制度密切相关。单级峰时效（T6）状态下合金的强度最高,但是其抗应力腐蚀（SCC）性能及断裂韧性最低;双级过时效（T74和T73）状态下材料的断裂韧性和抗SCC性能明显提高,但是其强度牺牲较多;与T6相比,RRA时效处理可明显提高合金的抗SCC性能,且强度牺牲较少,仅下降2％左右,同时断裂韧性也有一定提高。     

双级时效对7075合金应力腐蚀性能影响

双级时效处理虽能有效提高7075铝合金抗应力腐蚀开裂(SCC)性能,但同时会导致合金力学性能降低。为了同时提高7075铝合金的拉伸性能和抗SCC性能,并优化双级时效参数,对双级时效处理7075合金进行了正交试验。通过扫描电镜和透射电镜在慢应变速率实验中研究7075合金的SCC行为。结果发现,在130 ℃条件下保温4 h后,在170 ℃条件下保温8 h,合金抗拉强度、伸长率和应力腐蚀指数I_SSRT分别为488 MPa、10.8%和0.095。      

时效制度对Al–Zn-Mg合金组织和抗应力腐蚀性能的影响

采用慢应变速率拉伸应力腐蚀、室温拉伸、透射电镜等检测方法,研究传统T5、T73时效处理,以及新型T5I4、T5I6断续时效处理对Al–Zn-Mg合金微观组织、室温拉伸性能及抗应力腐蚀性能的影响.结果表明:断续时效T5I4处理后材料抗拉强度为400.0 MPa,明显高于传统T5及T73态样品,但材料抗应力腐蚀性能变差,应力腐蚀敏感系数为5.7%;而经断续时效T5I6处理后,材料的抗拉强度为408.5 MPa,较T5I4态相比有所提升,与此同时抗应力腐蚀性能也得到明显改善,应力腐蚀敏感系数为3.2%,该值明显小于T5I4及T5态;T5I4态晶内析出相平均粒径为2.0 nm,体积分数为8.8%,均明显小于其他3种时效制度,其晶界析出相为细小且连续分布的点状析出相;而经T5I6时效处理后晶内析出相体积分数为24.6%,明显大于其他3种时效制度,晶内析出相平均粒径(4.1 nm)较T5I4态有所增大,但依然小于T5、T73态,其晶界处析出相与T5I4态相比更加粗大,呈断续分布形貌.     

时效制度对Al–Zn?Mg合金组织和抗应力腐蚀性能的影响

采用慢应变速率拉伸应力腐蚀、室温拉伸、透射电镜等检测方法,研究传统T5、T73时效处理,以及新型T5I4、T5I6断续时效处理对Al–Zn?Mg合金微观组织、室温拉伸性能及抗应力腐蚀性能的影响。结果表明:断续时效T5I4处理后材料抗拉强度为400.0 MPa,明显高于传统T5及T73态样品,但材料抗应力腐蚀性能变差,应力腐蚀敏感系数为5.7%;而经断续时效T5I6处理后,材料的抗拉强度为408.5 MPa,较T5I4态相比有所提升,与此同时抗应力腐蚀性能也得到明显改善,应力腐蚀敏感系数为3.2%,该值明显小于T5I4及T5态;T5I4态晶内析出相平均粒径为2.0 nm,体积分数为8.8%,均明显小于其他3种时效制度,其晶界析出相为细小且连续分布的点状析出相;而经T5I6时效处理后晶内析出相体积分数为24.6%,明显大于其他3种时效制度,晶内析出相平均粒径（4.1 nm）较T5I4态有所增大,但依然小于T5、T73态,其晶界处析出相与T5I4态相比更加粗大,呈断续分布形貌。      

时效制度对工业规格喷射成形7055铝合金组织和性能的影响

采用全自动控制往复喷射成形工艺制备大规格7055铝合金锭坯。锭坯经热挤压和双级固溶处理后,在不同时效工艺条件下进行双时效处理,测定时效态合金的抗拉强度(σb)、屈服强度(σ0.2)、伸长率(δ)、硬度(HRB)和电导率(γ),并观察其微观组织,研究时效制度对合金组织和性能的影响,并与120℃/24 h单级时效的合金样品进行性能对比。结果表明,锭坯经120℃/24 h时效处理后获得最高强度,抗拉强度(σb)高达725 MPa,屈服强度(σ0.2)为685 MPa,伸长率(δ)10.0%,硬度为96 HRB,电导率为30%IACS;双级时效后获得较好的塑性和抗应力腐蚀能力,但强度较低,且随着二级时效温度升高和时效时间延长,合金强度下降,伸长率增加,电导率提高。通过对正交实验结果进行分析,确定最佳双级时效处理工艺为:120℃/8 h+170℃/8 h,其综合性能最佳,σb、σ0.2和δ分别达到659 MPa、630 MPa和11.7%,硬度和电导率分别为95 HRB和39%IACS。与单级时效处理相比,电导率提高30%,抗应力腐蚀性能显著改善。     

时效制度对喷射成形7055铝合金机轮轮毂锻件性能的影响

采用全自动控制往复喷射成形工艺制备直径为495 mm的大规格7055铝合金锭坯,经热挤压、2次锻压成形和双级固溶处理后,分别进行T76(120℃/6 h+160℃/8 h)、T74(120℃/6 h+160℃/18 h)和T73(120℃/6 h+160℃/30 h)双级时效处理,测定时效态锻件各取样部位的抗拉强度(σb)、屈服强度(σ0.2)和电导率(γ),并与单级时效T6态(120℃/24 h)的锻件进行对比,研究时效制度对轮毂锻件各取样部位性能和断裂方式的影响。结果表明,随二级时效时间延长,锻件的抗拉强度与屈服强度均降低,屈强比也略有降低,但断裂韧性提高;在T74和T73时效状态下试棒拉断后为典型的韧性断裂;随二级时效时间延长,锻件的断裂韧性和电导率均呈升高趋势,并改变T6态下的脆性断裂特征,满足机轮的应用要求。     

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.