TC4钛合金双光束激光填丝焊成型工艺研究

随着社会的发展,对焊接工艺的要求越来越高,传统的钛合金激光自熔焊成型工艺落后,所以利用此技术焊接后,会造成表面凹凸不平,存在不饱满的缺陷,影响美观。为满足人们工作的需要,研究了一种TC4钛合金双光束激光填丝焊成型工艺。本文通过对TC4钛合金进行双光束激光填丝焊试验,研究其存在的优势。结果表明:对焊接参数进行调整、优化可以改善焊缝成形的质量。     

TC4钛合金丝材焊件冲击失效分析

采用钨极氩弧焊接工艺获得TC4钛合金丝材防护架,随后对其进行冲击试验,发现多处焊接点发生断裂失效。为此,研究了TC4钛合金丝材焊接处的组织、显微硬度以及断口形貌。结果表明,在快速加热及冷却的热循环作用下,焊件焊合区域产生马氏体相,主要以α'相形式存在,另有少量的α″相;焊合区域的局部显微维氏硬度平均值达5.5 GPa,是母材区域硬度值的近1.5倍;相比于TC4钛合金丝材弯曲断裂的韧性断口形貌,焊件断口存在解理台阶,为脆性断裂,这主要归结于马氏体的存在使得焊接处塑性和韧性降低。     

碳纳米管对TC4钛合金激光焊焊缝成形和组织的影响

选取羟基化多壁碳纳米管作为表面活性剂对TC4钛合金进行活性CO2激光焊接,焊后测量并计算了焊缝的熔深、熔宽及深宽比,观察分析了焊缝显微组织,测定了接头硬度和焊缝的物相组成。结果表明:TC4钛合金表面涂覆质量分数为4%的碳纳米管溶液,形成的涂覆层均匀致密;在给定焊接参数条件下,该涂覆层可使焊缝熔深增加约6%,熔宽降低约4%,深宽比增加约10%;涂覆碳纳米管可以增加激光吸收率,使得焊缝温度升高、冷却速率增大,因而涂覆碳纳米管的焊缝β晶粒较细,晶内的α'相较未涂覆碳纳米管的短小;碳纳米管对焊缝硬度和焊缝的物相组成无明显影响。     

激光拼焊焊缝显微组织及精细结构分析

将厚度为1.2 mm和0.8 mm的低碳冷轧汽车薄板通过激光拼焊工艺焊接成一个整体,利用光学金相显微镜和透射电子显微镜研究了焊缝处的显微组织和精细结构,并利用显微硬度计连续地测量了焊缝处的显微硬值。结果表明,该钢激光拼焊缝焊处组织为通过块型转变形成的块型铁素体,其位错密度高于多边形铁素体,块型铁素体硬度介于先共析铁素体与贝氏体之间。     

激光焊接对TC6钛合金组织及性能的影响

激光焊接技术采用高能密度熔焊焊接方式,利用激光束将被焊金属加热至熔化温度以上熔合成焊接接头。超高强度TC6钛合金是一种综合性能优良的新型金属材料。本文采用激光焊接技术,研究了在指定的激光功率下激光焊接对TC6钛合金组织及力学性能的影响,为激光焊接工艺参数的确定提供依据。综合分析可知当激光功率为3.1kW、激光速度为1.75mm/min时,TC6钛合金焊接接头组织最细小、均匀,表现出较高的优良性能,其抗拉强度最高值可达到901.7MPa。     

TA18钛合金板材焊接工艺对比研究

研究了直流钨极氩弧焊(直流TIG)、脉冲钨极氩弧焊(脉冲TIG)和激光焊接3种不同焊接工艺对TA18钛合金焊接接头宏观形貌、显微组织和力学性能的影响。结果表明，与直流TIG焊接工艺相比，脉冲TIG焊接工艺的高频脉冲促使电弧能量集中，整体的焊接热输入减小，焊缝宽度降低；激光焊接工艺可显著降低焊接接头宽度，与直流TIG焊接工艺相比，焊接接头宽度减少约69.5%。TA18钛合金激光焊接接头显微组织主要为网篮状排列的针状马氏体α′相及少量块状相变α相，且针状马氏体α′相更加细小。此外，激光焊接接头具有更高的显微硬度，但弯曲性能相对较低。     

TC4钛合金真空电子束焊焊接接头组织性能与腐蚀行为研究

真空电子束焊具有能量集中度高、热影响区小等优点,在钛合金焊接领域被广泛应用。本文研究了TC4钛合金薄板真空电子束焊对接组织性能以及在不同腐蚀介质中的腐蚀行为及特征。研究结果表明:接头母材区组织是等轴α相和间隙β相的机械混合,焊缝区组织为针状马氏体(α'相),热影响区由原始α相、β相加α'相构成;接头显微硬度明显高于母材且随着与母材距离的增加,硬度逐渐增加;同时焊缝区网篮组织的形成使接头拉伸强度和断面收缩率更高,塑性更好。在3.5%NaCl溶液中,母材的腐蚀倾向大于焊缝,而在10%HCl溶液中则相反,焊缝成为薄弱环节;同时,焊接接头在10%HCl溶液中自腐蚀电流显著高于在3.5%NaCl溶液中,说明介质对接头的电化学腐蚀性能影响显著。     

车用TC15钛合金激光焊接接头显微组织及力学性能研究

通过拉伸试验、硬度测试及金相分析等方法,对TC15钛合金激光焊接接头的显微组织和力学性能进行研究。结果表明,焊缝的深宽比在4~6之间波动,焊缝区域的晶粒形貌为柱状结构,且从焊缝中心线往外呈对称分布状态,主要为β相大晶粒。热影响区组织由细晶区、粗晶区及再结晶区构成,熔合线附近区域的晶粒明显粗化。焊缝区具有相对稳定的硬度值分布,硬度与热影响区的粗晶区相近。较低焊接电流焊缝试样具有最低的抗拉强度,其断裂部位为焊缝区;随着焊接电流的增大,焊接接头抗拉强度得到提高。     

TC4钛合金线性摩擦焊接头组织及性能研究

采用XMH-160型线性摩擦焊机焊接TC4钛合金板材,观察了焊接接头形貌及焊缝组织,测试了焊接接头的力学性能.结果表明,TC4钛合金适于采用线性摩擦焊接,焊接接头的室温拉伸性能、冲击韧性和高周疲劳性能不低于母材.其线性摩擦焊接头大致可以分为焊缝区和塑性变形区两个区域,焊缝区域原始组织被破碎,晶粒细小;塑性变形区域原始片层组织被压扁拉长,与焊接振动方向呈近平行的流线状.     

BTi -62421S高温钛合金超塑成形与焊接工艺研究

设计了新型高温钛合金BTi - 62421S舵面模拟件超塑成形模具,结合超塑成形与几种典型焊接技术,研究了激光焊、滚焊等焊接方法对超塑成形的影响,最终研制出钛合金舵面模拟件超塑成形零件.结果表明采用激光焊与滚焊工艺都能很好地保证两层钛合金板气密性要求,激光焊接工艺效率更高、表面质量更好,选择适当的激光焊接工艺参数可获得...     

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。     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.     

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.