耐热不锈钢焊接缺陷产生的原因及防治措施

根据耐热不锈钢的化学成分组成,分析了焊接过程中产生裂纹的主要原因,提出了具体的工艺措施,从而改善焊缝的质量,获得优质的焊接接头。     

焊缝宽度对碳钢对接接头残余应力分布的影响

针对当前大量焊接结构采用对接接头形式,存在焊缝宽度影响结构表面残余应力分布的问题,课题组结合有限元仿真软件ABAQUS建立了一种利用双椭球摆动热源进行窄间隙焊接的平板对接模型,并使用焊缝非线性的热弹塑性有限元法,计算出Q235 A钢在4种不同焊缝宽度下对接焊接接头的残余应力分布.计算结果表明:小尺寸焊缝宽度的对接接头在...     

00Cr19Ni10不锈钢焊接接头性能的研究

文章主要对00Cr19Ni10不锈钢的焊接接头进行研究,通过对不锈钢板的焊接,对焊接接头进行拉伸试验、显微硬度、微观组织及铁素体数量测量试验;测试得出00Cr19Ni10不锈钢焊接接头的力学性能的准确数值,通过对接头组织的金相分析和铁素体数量测量,得出组织中有组织长大趋势会产生粗大柱状晶,00Cr19Ni10的铁素体含量控制在3%～8%区间内,可以防止热裂纹的产生并提高了焊接接头力学性能。     

浅谈化工企业中耐热钢的焊接

在化工装置中锅炉是一个很重要的环节,大型锅炉在制造和安装过程中,耐热钢的应用范围比较广泛,还有一些难于焊接的耐热钢,在焊接生产过程中,易发生各种焊接缺陷,如焊接冷裂纹、焊接热影响区裂纹、焊接气孔、焊缝冲击韧度不稳定、时效脆化、焊接接头蠕变断裂强度弱化、高温运行早期失效等焊接缺陷和焊接质量问题。     

球罐组对焊接的质量控制

球罐环带焊缝及丁字缝是球罐质量的薄弱环节,安装过程中严格执行合理的组装工艺、焊接工艺可有效控制球罐的整体安装质量。     

球罐组对焊接的质量控制

球罐环带焊缝及丁字缝是球罐质量的薄弱环节,安装过程中严格执行合理的组装工艺、焊接工艺可有效控制球罐的整体安装质量。     

机械振动对激光填丝焊接接头组织和疲劳性能影响

针对激光填丝焊接过程中存在气孔、飞溅、夹渣和疲劳性能差等缺点,课题组提出了基于机械振动技术的激光填丝焊接方法。课题组采用机械振动与激光填丝焊接相耦合的方法研究了机械振动对焊缝形貌、组织、力学性能和断裂机理的影响。结果表明:机械振动可以改善316不锈钢焊接接头,减少焊缝中的柱状晶,增加树枝晶和等轴晶,提高了焊缝硬度; 3种振动频率下焊接接头的残余应力均较高,与振动频率0和524 Hz相比,1 055 Hz振动频率的焊缝残余应力更低;疲劳断口均呈解理断裂,但是与524 Hz振动频率相比,1 055 Hz振动频率具有更低的裂纹扩展率,更好的疲劳性能。     

液化气球罐裂纹产生原因分析及修复

对扬子石化炼油厂油品车间液化气球罐G831内外裂纹缺陷分布进行了统计,结合液化气罐工艺运行特点和腐蚀机理,对球罐焊缝热影响区母材出现的球墨化裂纹和湿H2S腐蚀原因进行了详细分析。此外,对球罐裂纹进行了修复处理、强度试验和安全评估,并提出了今后确保安全运行的保障措施。     

Q345E与20钢异种钢管氩电联焊工艺研究

采用氩电联焊对Q345E和20钢异种钢管进行焊接试验及焊接接头力学性能测试。结果表明：Q345E和20钢异种钢管焊接接头具有良好的工艺性能,X射线探伤不低于Ⅱ级,抗拉强度分别为542 MPa和536 MPa,-20℃冲击功不低于33 J,侧弯试样弯曲面焊缝和热影响区没有裂纹,满足NB/T 47014—2011要求。     

S31603不锈钢焊接工艺及性能研究

对管内充氩气保护在二氧化碳压缩机不锈钢S31603管道中的焊接效果进行检测。结果表明：焊接接头射线和渗透检测都为I级，抗拉强度不低于616 MPa,-50℃冲击吸收能量达到55 J以上，硬度小于187 HBW,面弯和背弯以及耐腐蚀性能试验合格，结果符合NB/T 47014—2011和相关技术要求。焊缝组织为树枝状奥氏体加少量铁素体，铁素体有利于提高焊缝金属的耐晶界腐蚀能力和抗裂纹敏感性。     

蜡印冰纹特征分析及审美价值

冰纹是蜡印图案的主要特征,为了更好地在现代蜡印及仿蜡印图案创作中应用及表现出逼真的冰纹效果,对自然生成的蜡印冰纹形态、色彩特征及美学价值做了详细的讨论和评价。分析了影响蜡印冰纹形成的因素,发现在不同的制作条件下,冰纹的线条呈现出不同的粗细、曲度特征,在冰纹交叉处会有不同程度的加粗现象。面料上蜡后的裂蜡方式决定了冰纹的形态,可产生龟裂状、平行状、方格状等形状的冰纹图案。同时,冰纹的形态表征与蜡印图案形状大小也有一定的关系。染色时冰纹受蜡层开裂大小及先后的影响,会产生不同的染色深浅和色彩层次,局部蜡质与面料贴合不牢的部位还会出现晕染效果。此外,从审美角度看,蜡印冰纹具有缺陷美、无序美和肌理美等美学特征。     

ER70S-6盘条拉拔断裂原因分析

焊接用ER70S-6盘条在拉拔过程中断裂,细拉钢丝断口以杯锥状为主,粗拉钢丝断口以斜茬状为主。对φ1.2mm钢丝杯锥状断口进行扫描电镜分析,试样心部存在大量马氏体组织,马氏体与基体之间产生大量的显微裂纹。对盘条金相组织进行观察,盘条心部存在马氏体,表面出现全脱碳层,且脱碳后的晶粒尺寸较大。对斜茬状断口金相组织进行观察,裂纹与钢丝表面约呈45°角,裂纹源位于表面。分析表明,ER70S-6盘条中的锰、硅含量较高,造成铸坯凝固过程中中心缩孔处合金元素正偏析,盘条轧制后形成异常组织。采用合理的浇铸温度、拉坯速度、冷却水量等,降低缩孔级别,减轻中心偏析,提高钢坯内部质量,保证成分均匀稳定,控制轧制时的尺寸精度和轧制张力,能够有效降低焊丝拉拔断裂次数。     

防止大型圆筒形钢制贮罐底板的焊接变形

为防止大型圆筒形钢制贮罐底板的焊接变形,可从底板的结构设计、焊接方法等方面加以解决。     

Crack formation in unfinished siding of aspen (Populus tremula L.) and Norway spruce (Picea abies (L.) Karst.) during accelerated weathering

Crack formation is a serious defect that may reduce the lifetime of unfinished wood in service. An accelerated weathering test was carried out to study crack formation of solid wood board specimens of aspen (Populus tremula L.) and Norway spruce (Picea abies (L.) Karst.). The influence of the boards' distance from the pith was also studied. The aspen specimens developed a higher number of cracks than the spruce specimens. However, these cracks were shorter and less injurious than those propagating in spruce wood. It is concluded that a solid wood siding of aspen will show at least as good a performance as spruce regarding crack injuries. For both aspen and spruce, boards taken from near the pith had a lower proportion of long cracks than boards taken further out. This supports the rule that boards with a high proportion of annual rings perpendicular to the surface (the boards near to the pith) have a higher resistance to crack formation than boards with a high proportion of horizontal annual rings.     

球罐爬壁打磨机器人结构设计及其吸附力仿真

针对目前球罐壁面打磨工作存在着效率低下、劳动强度大、施工周期长、安全性差等问题,提出了利用爬壁机器人携带打磨设备进行打磨工作的方案。分析了爬壁打磨机器人功能原理并找出设计中的难点;设计了一种双履带间隙磁吸附式爬壁打磨机器人机械结构;利用直线型Halbach永磁阵列设计了一款可调间隙式吸附机构,并对其进行ANSYS有限元仿真,证明了这种吸附结构具有较大的磁能利用率,得到了它与壁面间的相互作用力随间隙垂直距离变化关系曲线,同时也为确定吸附力大小提供了依据。     

基于断裂力学的立式杀菌锅全寿命疲劳分析

目的:研究一种新型立式杀菌锅在热机循环载荷下的疲劳强度,特别是在锅体出现裂纹后的剩余疲劳寿命以及影响杀菌锅疲劳裂纹扩展的因素.方法:从杀菌锅结构完好的设计疲劳寿命和有裂纹后的剩余疲劳寿命两个方面对其进行全寿命疲劳分析.采用Workbench分析杀菌和3种循环载荷下杀菌锅的力学特性;基于SGN曲线研究杀菌锅在3种交变应力下的设计疲劳寿命;基于断裂力学原理研究初始裂纹尺寸、压力、温度对有裂纹杀菌锅应力强度因子和剩余疲劳寿命的影响.结果:此类立式杀菌锅的设计疲劳寿命为5×10⁵次,满足设计需要且有一定安全余量;基于断裂力学分析得出杀菌锅裂纹尺寸寿命曲线,对含缺陷杀菌锅剩余寿命进行预测,具有一定创新性.结论:使用过程中应关注锅体内部裂纹的产生和扩展情况,可以根据试验提出的方法对杀菌锅裂纹缺陷进行强度分析和寿命预测.     

Uptake, retention, and repellency of a potential carrier of active ingredients in crack and crevice treatments for stored-grain beetles

Crack and crevice treatments are important in modern stored-beetle management, because: (1) pests are abundant in such microhabitats, (2) they potentially deliver insecticides to insect pests without contaminating food products, and (3) they can significantly reduce the need for broadcast spray applications and/or fumigations. As part of on-going research into the development of novel insecticide delivery systems to be used in processed and unprocessed food environments, we examined uptake and behavioural responses of Oryzaephilus surinamensis to an electrostatically chargeable powder, Entostat^TM. Entostat is a processed plant wax and has been identified as a potential carrier for active ingredients to be delivered to cracks and crevices in food facilities. Depending upon the initial Entostat concentration in rolled oats, 0.03–0.26 μg powder was extracted from individual beetles 72 h after being transferred from treated to untreated food. SEM images showed that Entostat adhered to all body parts, including joints, between body segments, and at the insertions of body hairs. Choice experiments showed that O. surinamensis individuals were repelled, when rolled oats in cracks contained >5% Entostat. In a three-choice experiment cracks contained: (1) untreated oats, (2) oats mixed with 5% (w/w) Entostat, or (3) oats mixed with 5% (w/w) Entostat and a piece of filter paper containing a beetle attractant which was also inserted into the crack. The beetle attractant did not significantly increase the attractiveness of the crack in which it was applied, but the average powder uptake of beetles from cracks treated with the attractant was significantly higher than from the other cracks. Results presented here suggested that Entostat adhering to insects was retained over several days and that considerable amounts of Entostat were taken up even when beetles were offered a choice between treated and untreated cracks.     

失效钛换热器的修复

分析了钛换热器管板与换热管焊接接头补焊失效的原因,提出了实施修复的可靠措施。     

In vitroassessment of psychrotrophicClostridiumspp. as possible causative agents of bone-taint in beef

The present study was undertaken to determine whether psychrotrophicClostridiumspp. could induce a bone-taint condition when inoculated into the joints of hot bovine hind legs that were then subjected to marginally abusive cooling conditions. The stifle and hip joints of the hind legs of freshly slaughtered cattle were inoculated with single-strain cultures of 14 psychrotrophicClostridiumspp. isolated from spoiled chilled meat or with cultures of a mesophilic or a psychrotrophic reference strain. Inoculated legs were chilled in a cooling tunnel programmed to simulate marginally abusive cooling (deep tissue temperature reduced from 38 to 20°C in 20 h). After cooling, deep-seated, strongly offensive odours were evident in some of the inoculated joints and tissue surrounding those joints. It can, therefore, be postulated that at least some strains of psychrotrophicClostridiumspp. have the potential to be primary causative agents of bone-taint.     

冷镦钢线材表面裂纹形成原因分析

根据冷镦钢线材生产及冷镦开裂的裂纹形貌 ,把裂纹分为平行连续裂纹、单条连续裂纹和断续裂纹 ,研究分析认为 ,平行连续裂纹是轧件存在耳子造成的 ,单条连续裂纹是由道槽或导卫划伤引起的 ,断续裂纹则是连铸坯表面裂纹造成的 ,针对产生裂纹的原因提出相应改进措施。