429铁素体不锈钢焊接微观组织和晶间腐蚀行为研究

本文通过高频焊对429铁素体不锈钢管进行焊接,观察相应的焊缝组织。通过金相组织观察、布氏硬度检测和晶间腐蚀实验等,分析了该铁素体不锈钢焊接处组织和性能,以及其晶间腐蚀对该铁素体不锈钢腐蚀行为的研究。实验结果表明,429铁素体不锈钢的焊接会使得焊缝区、热影响区处铁素体组织受热高温发生奥氏体化并且会析出碳化物颗粒。焊接后焊缝的硬度高于原材的硬度。晶间腐蚀结果表明,429铁素体不锈钢经焊接后的焊缝区域耐腐蚀性能很强。焊缝区晶粒细小均匀,在表面形成致密钝化膜保护焊缝免受晶间腐蚀影响,提高了该不锈钢稳定性。     

钛基非晶合金电子束焊接热力耦合模拟及非晶化

根据电子束焊接焊缝形貌特征及其深宽比大等特点,选用复合热源作为热源模型.通过线性插值等方式估计材料热力学参数随温度变化,模拟Ti基非晶合金电子束焊接温度场.模拟结果与实际焊缝取得良好的吻合,验证了热源模型的准确性.获得一定变量参数下电子束焊接钛基非晶合金温度场及热循环曲线.在温度场的基础上再进行焊接应力场的模拟,获得残余应力分布曲线.实验验证整个焊件没有晶化相析出,验证了该焊接工艺的可行性.      

特大型挖掘机铲斗体焊接温度场分析

根据焊接的实际工艺建立了多层多道焊的有限元数值分析模型,对特大型挖掘机铲斗体关键的焊缝处使用过渡性网格进行划分。利用ABAQUS有限元软件对铲斗体焊接温度场进行了模拟仿真,得到其焊接过程的温度场的分布规律及热循环动态变化过程。     

钛元素的添加对超纯铁素体不锈钢焊缝区等轴晶组织的影响

等轴晶组织对于铁素体不锈钢焊缝区的力学性能,特别是韧性、延伸率等影响很大。总结了在铁素体不锈钢焊缝中等轴晶的形核机理。对于439超纯铁素体,加入钛元素可以在焊缝凝固前的熔融状态析出TiN的析出相,有利于钨极氩弧焊(TIG)的焊缝等轴晶的形成。在短暂的焊接过程中,可以通过控制铁素体不锈钢Ti和N的浓度积以及N的含量等来控制母材TiN最初的析出形态、析出数量;同时,通过Ti和N的合适匹配以及合适的焊接工艺参数保证焊缝区的温度梯度,这些都是焊缝区等轴晶比例的必要控制因素。     

激光焊接速度对焊缝组织和硬度分布的影响

利用激光焊接工艺焊接核级不锈钢,通过改变激光焊接速度得到不同的焊接接头.采用金相显微镜、扫描电子显微镜等手段研究了熔深比、δ/γ比、组织形貌以及焊缝中各相的成分.通过显微硬度测试了焊缝接头上硬度分布.随着焊接速度的增加,焊缝熔深比线性增加,焊缝中δ-铁素体含量增加,岛状组织增多,板条状组织增多,蠕虫状组织减少,焊缝区的平均硬度值增加.      

基于ANSYS的钛合金管口激光焊接有限元模拟

基于热弹塑性有限元方法,建立激光焊接过程的热力学计算模型,利用三维有限元分析软件ANSYS,开发其APDL二次语言,使用“生死单元”技术,实现了对BT20钛合金管口激光焊接过程温度场和应力场的有限元模拟。结合数值计算,对有限元模拟问题进行分析,并讨论了激光焊接过程采用瞬间空冷10s后,试件内部的应力分布情况。     

惯性摩擦焊过程温度场及变形场的数值模拟

惯性摩擦焊接是一种广泛应用的高效、可靠、节能及环保的固态焊接方法.该方法在航天航空领域已广泛应用.本文分析了惯性摩擦焊接过程高度非线性的特点,在此基础上建立了一个基于二维轴对称的惯性摩擦焊接过程有限元热力耦合计算模型.计算区域划分成四节点等参单元,热物性参数和力学性能参数随温度变化,同时考虑了焊接热流随时间的变化、表面对流和辐射换热以及飞边的影响.利用有限元分析软件MSC Marc对同质材料GH4169-GH4169惯性摩擦焊接接头区的瞬态温度场及应力-应变场的分布进行了计算分析.使用热电偶点对焊接接头部分若干点的温度进行了实时测量.结果表明温度场的计算结果与实测值符合较好.另外,还讨论了工艺参数对摩擦焊接接头区应力分布以及飞边形状的影响.     

Q960超高强钢多道焊接头残余应力的数值研究

以Q960超高强钢为研究对象,基于有限元软件,建立热—冶金—力学有限元模型,模拟焊接温度场和残余应力分布.计算结果与接头截面熔池形貌和盲孔法测量的表面应力结果吻合良好,验证了有限元模型的准确性.基于验证模型,讨论和分析了考虑固态相变对Q960超高强钢多道重熔过程中表面及内部应力的分布特征.结果表明:考虑固态相变时,Q960超高强钢单道焊后,焊接接头以拉伸残余应力为主,峰值应力位于热影响区.同时,固态相变效应能够显著降低焊缝中残余应力的大小,以及显著影响横向残余应力的分布.此外,随着焊道数的增加,焊缝中心的横向残余应力呈"阶梯"趋势上升,且在热影响区位置出现局部压应力峰值.     

HR800CP复相高强钢板焊接接头的显微组织和力学性能

采用激光焊、80%Ar+20%CO_2混合气体保护焊匹配CHW-60C焊丝,对HR800CP复相高强钢板进行了焊接,对其焊接接头的显微组织与力学性能进行了研究。结果表明:激光焊缝的焊缝中心和热影响区组织为马氏体和贝氏体,焊缝中心和热影响区硬度值均高于母材,弯曲180°时未出现沿焊缝的开裂情况,接头抗拉强度为799 MPa,低于母材的抗拉强度,原因是焊缝的表面有凹陷。混合气体保护焊接头焊缝组织为针状铁素体、块状铁素体,粗晶区组织为板条状马氏体+贝氏体组织,正火区组织以贝氏体为主,熔合线附近存在相对较软的区域,接头的抗拉强度755 MPa,低于母材的抗拉强度。     

SUS410S铁素体不锈钢焊接性能研究

在不锈钢加工工艺中,焊接是最主要的必不可少的加工技术之一。本文以SUS410S铁素体不锈钢为原料,采用手工钨极氩弧焊方法,选用日本生产的交直流氩弧焊机,以ER30gL焊丝为焊接填充金属材料。研究其焊接性能。试验结果表明：在选定的焊接工艺参数条件下,焊接接头性能满足要求;无损检测焊接接头内不存在裂纹、未熔合、未焊透和条形缺陷,抗拉强度、面弯和背弯弯曲检验结果良好,宏观检查受检面焊缝均未发现任何焊接缺陷,耐晶间腐蚀试验未发现明显的裂纹,焊缝为细长的条状奥氏体加少量的8铁素体组织,热影响区为铁素体加马氏体组织。     

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.