共查询到19条相似文献,搜索用时 140 毫秒
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由于耐蚀性突出,钛制压力容器已广泛应用于化工过程装置,为确保安全,采用声发射技术对其服役状态进行及时、有效地安全评估的前景广阔。针对TA2常见的工程状态,开展了淬火马氏体和焊缝马氏体两种微观组织声发射特性的理论分析和试验研究,通过恒速率拉伸和裂纹扩展监测试验,获得了形变和断裂物理源机制的声发射特性。采用历程分析结合微观观察,证实了α'马氏体团簇的塑性变形和马氏体板条边界的开裂,是拉伸过程中声发射两次增长阶段的主要物理来源;沿马氏体板条间或基体与马氏体边界的裂纹扩展是疲劳裂纹稳定生长过程中的强声发射源,是声发射信号计数率-应力强度因子幅曲线呈现阶梯状上升的物理成因。研究结果为相关材料承压设备的声发射检验提供了经验数据和分析方法,为工程实践奠定基础。 相似文献
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《机械设计与制造》2017,(5)
机械结构件中的应力集中使得结构极易产生裂纹并逐渐扩展,裂纹扩展时伴有声发射信号,因此有必要对结构件中裂纹扩展时的声发射信号进行特征研究。为研究金属板件中的裂纹声发射源特征行为,通过分析板件中的裂纹声发射源,从理论上推导了裂纹声发射的幅值和频率特征表达式。在裂纹扩展过程中,金属板件的裂纹声发射信号幅值与声发射源的开裂长度和拉伸应力的乘积成正比,频率与裂纹开裂速度成反比,且与裂纹开裂长度成正比。用声发射检测系统对预制有初始裂纹的金属板件进行拉伸状态下的声发射监测,通过对声发射信号求取功率谱密度估计,实现不同声发射信号以功率谱在频域的分布为信号特征的有效区分。实验结果与理论分析相符合,研究结果对金属板件的裂纹声发射检测技术具有重要意义。 相似文献
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低合金钢压力容器的开裂失效,大部分属于穿晶型氢致裂纹(Hydrogen Induced Crac King,HIC),例如:阶梯状裂纹、鱼眼、八字裂纹等。氢致裂纹是钢材化学成分、显微组织和残余应力的函数。改善钢材化学成分和性能,是消灭氢致裂纹的重要对策之一,七十年代末日本开发成功的和我国1987年开发成功的CF钢,便是一例。据《神户制钢技报》1987年No.4期报导, 相似文献
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X90管线钢在石油天然气管道中具有广泛应用前景,其焊接接头在服役过程中存在氢致开裂(Hydrogen induced cracking,HIC)倾向。采用电化学氢渗透试验和预充氢慢应变速率拉伸试验(Slow strain rate tensile test,SSRT),对X90管线钢焊接接头的氢捕获效率和氢致开裂敏感性进行了研究。利用场发射扫描电子显微镜(Field emission scanning electronic microscope,FE-SEM)对试样断口形貌及裂纹处夹杂物进行观察和分析,采用氢微印技术(Hydrogen microprint technique,HMT)对显微组织中氢的局部分布和聚集进行分析。结果表明,不同充氢电流密度下,X90管线钢焊接接头SSRT试样的断裂位置均为焊缝,其氢致开裂敏感性明显高于母材。与X90管线钢母材相比,焊缝中氢扩散系数较小,氢浓度、可逆和不可逆氢陷阱密度均较高。焊缝中的针状铁素体、贝氏体组织晶界及其亚晶界和夹杂均是有效的氢捕获陷阱,具有较高的氢捕获效率;焊缝中尺寸大于2μm夹杂物的数量多于母材,氢致裂纹易在富Al、富S、富Si夹杂... 相似文献
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X100在海洋石油领域具有广泛应用前景,服役过程中不可避免受到氢的影响。以API X100管线钢为研究对象,通过电化学试验和声发射监测等试验方法,研究不同电化学充氢时间对管线钢力学性能和断裂韧度的影响;结合微观形貌,探究充氢时间与X100管线钢作用机理。结果表明:管线钢本身具有良好的强韧性,电化学引入氢后,材料的屈服强度和抗拉都会降低,且随着充氢时间的增加,性能恶化加剧。充氢后,材料性能的恶化,主要归因于引入的氢会扩散到材料的应力集中缺陷处,与缺陷处组织发生交互,最终导致材料性能变化。研究结果可为高强钢服役时的性能劣化预测及开裂监控提供依据。 相似文献
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Acoustic emission signals generated by sliding friction between two flat steel surfaces are characterized. A test fixture to simulate the reciprocating motion between the two surfaces under controlled conditions is developed. Sliding friction under several combinations of surface roughness, relative velocity, and normal pressure was examined. Wideband AE sensors and instrumentation were used for acquiring and analyzing the acoustic emission signals. Acoustic emission events occurred primarily during the slip portion of the stick-slip cycles. AE waveform features obtained during these experiments were indicative of the tribological conditions. Frequency components in excess of 700 kHz were seen during these experiments. The characteristics of the experimentally observed acoustic emission signals were in general agreement with earlier numerical predictions. Friction related acoustic emission signals were distinguishable from those from other sources such as fatigue crack growth. The characterization of friction related acoustic emission signals is likely to be of value in many tribological and structural health monitoring applications. 相似文献
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Zakiah Abd Halim Nordin Jamaludin Syarif Junaidi Syed Yusainee Syed Yahya 《Journal of Mechanical Science and Technology》2015,29(4):1559-1570
Current steel tubes inspection techniques are invasive, and the interpretation and evaluation of inspection results are manually done by skilled personnel. Part A of this work details the methodology involved in the newly developed non-invasive, non-destructive tube inspection technique based on the integration of vibration impact (VI) and acoustic emission (AE) systems known as the vibration impact acoustic emission (VIAE) technique. AE signals have been introduced into a series of ASTM A179 seamless steel tubes using the impact hammer. Specifically, a good steel tube as the reference tube and four steel tubes with through-hole artificial defect at different locations were used in this study. The AEs propagation was captured using a high frequency sensor of AE systems. The present study explores the cluster analysis approach based on autoregressive (AR) coefficients to automatically interpret the AE signals. The results from the cluster analysis were graphically illustrated using a dendrogram that demonstrated the arrangement of the natural clusters of AE signals. The AR algorithm appears to be the more effective method in classifying the AE signals into natural groups. This approach has successfully classified AE signals for quick and confident interpretation of defects in carbon steel tubes. 相似文献
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V. R. Skal’skii D. V. Rudavskii T. V. Selivonchik 《Russian Journal of Nondestructive Testing》2009,45(9):636-645
The acoustic emission method for estimating damage to specimens made of thermally resistant steel is described as applied
in air and in a gaseous hydrogen medium. Acoustic diagrams (AD) of steel cracking and their interpretation are presented.
It is shown that thermal cycling of the steel in air and in a hydrogen medium leads to an increase in bulk damage to the steel.
It is shown that the exploited material is more subject to micro- and macrocracking under the influence of temperature and
the working environment. 相似文献
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声发射技术在冷库压力容器在线动态检验中的应用 总被引:2,自引:0,他引:2
通过对山东省冷库压力容器现状及冷库工作原理的了解,详细介绍了冷库压力容器利用声发射在线动态检验及评价的特点及目前的研究成果,并对声发射在线动态检测的原理进行了分析,指出利用声发射技术冷库压力容器罐体中的腐蚀、咬边、埋藏缺陷、应力集中、特别是钢板缺陷等均能检出,检验结果的可靠性及完整性与常规方法的开罐全面检验结果相符。 相似文献
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基于模态分析和小波变换的声发射源定位新算法研究 总被引:7,自引:4,他引:7
针对传统声发射源定位中,声发射信号到达传感器的时间受设定门槛电压影响很大,导致声发射源定位效果较差,提出了一种声发射源定位新方法。根据模态声发射理论,携带声发射源信息的声发射信号在结构中传播过程中,具有频散现象和多模态特性。因此,声发射源定位应基于同一频率下、同一模态导波到达各个传感器的时间和传播速度。通过对声发射信号进行Gabor小波变换的方法,在时频空间内确定某一频率下某一模态导波到达传感器的时间;并通过数值计算得到该频率处模态导波的群速度,从而实现声发射源的准确定位。通过薄板中声发射线源定位试验,证明了该定位算法的有效性。 相似文献
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多功能全多层高压氢气储罐 总被引:9,自引:0,他引:9
高压储氢具有储罐结构简单、压缩氢气制备的能耗较少、充装速度快等优点,已成为现阶段氢能储运的主要方式。氢气储罐是高压储氢的关键设备。目前,加氢站使用的高强钢制无缝压缩氢气储罐,由于结构上的原因,存在无抑爆抗爆功能、在线健康状态诊断困难、大容量时泄漏点多等缺点。为此,本文提出了一种多功能全多层高压氢气储罐,并应用于我国第一座站内制氢的加氢站。储罐由双层半球形封头、接管、加强箍、绕带简体和健康诊断系统组成,具有承压、抑爆抗爆、缺陷分散、健康状态在线诊断等多种功能。 相似文献