高强钢板拉伸断口分层缺陷成因的探讨

针对高强度钢Q690D 60~80 mm规格拉伸试验后试样断口出现分层的现象,利用金相显微镜、扫描电子显微镜及能谱仪对典型断口分层试样和断口合格试样进行试验分析。显微组织、断口形貌以及分层附近区域检测分析表明,该种分层与组织形貌和中心偏析无关,主要是小尺寸夹杂物和气泡的共同作用在厚度方向上对基体产生分割而造成的。     

高强钢板拉伸断口分层原因的分析与探讨

针对高强度钢Q690D60~80 mm规格拉伸试验后试样断口出现分层的现象,利用金相显微镜,扫描电子显微镜及能谱仪对典型断口分层试样和断口合格试样进行试验分析。通过对显微组织、断口形貌观察以及分层附近区域分析后发现,该种分层与组织形貌和中心偏析无关,主要是小尺寸夹杂物和气泡的共同作用在厚度方向上对基体产生分割而造成的。     

Q345钢板拉伸断口分层原因分析

针对Q345钢板在拉伸试验中出现断口分层的现象,利用金相分析技术,对拉伸试样断口形貌、夹杂物和显微组织进行了分析。通过分析认为,连铸坯中心偏析造成的板厚中心区域存在硫化物夹杂、贝氏体偏析带组织及心部裂纹,是导致钢板拉伸试样断口分层,延伸率不合格的主要原因。     

船用钢板拉伸断口分层形成机理分析

利用扫描电镜、光学显微镜对船用钢板拉伸断口试样进行形貌、夹杂物和显微组织检验分析,结果表明,钢板拉伸断口分层与心部成分偏析、过冷组织偏析带、铸造缺陷、轧后冷却过程中的热／组织应力和氢的存在有关,并提出了减缓钢板中心分层的措施。     

高强钢板拉伸断口分层缺陷成因探讨

对高强钢板常见拉伸断口分层缺陷的成因进行探讨,利用金相及扫描电镜观察拉伸试样断口组织、裂纹和钢中夹杂物,采用X射线衍射法测量分层试样的位错密度。研究发现钢板基体较高的位错密度是导致试样断裂过程中产生分层的主要原因,而夹杂物、晶界等缺陷是裂纹的起裂点,研究还发现分层与偏析、微观组织类型等无明显相关性。通过降低高强钢板的屈强比,可以显著改善分层缺陷。     

高强船板拉力分层原因分析及改进措施

利用金相显微镜、扫描电镜和电子探针等手段对高强船板拉伸试验中出现的分层现象进行了分析,认为大量硫化物和氧化物夹杂、轧制后未轧合的孔洞以及C、Mn成分偏析造成的带状组织是导致拉力分层的直接原因。通过采取真空处理完毕后向钢液中喂入硅钙线、优化连铸工艺、优化加热及控轧控冷工艺等措施后,船板钢轧后探伤合格率明显提高。     

高级别船板钢轧制过程夹杂物的行为研究

采用金相显微镜(OM)、扫描电镜(SEM)和能谱分析(EDS)等研究方法分别对莱钢F550船板钢300 mm厚铸坯、50 mm厚轧板和20 mm厚轧板的上表面、侧面和横截面夹杂物的种类、尺寸、成分及形貌等特征进行了分析.结果表明,F550船板钢中的夹杂物在轧制前后种类和尺寸没有明显变化,轧后大于5μm的夹杂物所占比例略有升高;船板钢中主要夹杂物有单相氧化铝和氧化物-硫化物复合夹杂;试样不同面上复合夹杂物的形貌特征各异,在轧制过程中试样各个面上复合夹杂物形貌发生明显变化,这与夹杂物的塑性和轧制受力情况有关.     

AH36船板钢拉伸试样断口分层缺陷的分析

AH36船板钢拉伸试验后试样断口出现分层现象,本研究采用扫描电镜与能谱仪、金相显微镜等手段对断口以及断口附近的截面组织进行了观察、检测和分析,并对拉伸后的船板钢试样进行了酸腐蚀低倍组织观察,指出分层现象与碳、硫和锰等元素偏析从而引起组织中出现贝氏体、马氏体有关,钢板厚度越大,分层情况越严重。     

船板钢拉伸断口分层原因分析及工艺改进

通过金相显微镜、扫描电镜对船板钢拉伸试样断口的金相组织、低倍组织、形貌进行分析,确定船板钢拉伸试样断口缺陷是由铸坯中的夹杂物、中心偏析和轧制工艺中形成的带状组织引起的。结合生产实际,提出了连铸坯二冷区凝固末端强制冷却措施,使得柱状晶生长速度变慢,等轴晶增多,减少了钢水静压力,减轻了中心偏析,船板拉伸断口分层缺陷得到有效控制。     

厚规格高层建筑用钢性能不合格原因浅析

通过直读光谱仪、金相显微镜、扫描电镜和能谱仪等手段,分别对Q345GJB钢性能不合格试样的化学成分、金相组织、夹杂物级别以及拉伸试样断口形貌进行检测分析,并与性能合格试样进行对比,发现性能不合格Q345GJB钢中含有较多的夹杂物和较严重的带状组织,沿轧制方向分布的大量长条状硫化物夹杂成为裂纹源,带状组织降低了钢板的横向塑性,导致拉伸断口出现分层,造成试样断后延伸率不合格。采取炼钢、轧钢工艺改进措施,改善板材内部质量,最终提高性能合格率。     

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.