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机械设备联接螺栓的失效分析 总被引:1,自引:0,他引:1
通过对螺栓失效件断口进行扫描电子显微镜、化学成分和微区元素的实验分析;查明螺栓失效断裂的原因,由于高强度钢表面镀镉后去氢不完全,致使螺栓在低应力下发生延迟破坏;提出预防措施,为后续产品的设计提供依据. 相似文献
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螺栓头部容易产生断裂。采用硬度试验机、金相显微镜及氢脆试验等手段对失效的螺栓与未失效的螺栓进行对比分析,结果表明该螺栓的失效为氢致断裂。由于热处理的工艺不当,渗碳层过深,导致过多的氢滞留在螺栓基材的内部,在随后的回火过程中氢不易扩散,是导致螺栓氢脆断裂的主要原因。后续的电镀工艺中未及时进行有效的去氢,更加重了氢脆断裂的风险。 相似文献
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本文通过对40Cr镀锌高强度螺栓断裂事故的分析和一系列延迟断裂试验结果分析,阐明了:在较高强度下,经镀锌的40Cr螺栓有很大的延迟断裂倾向。去氢处理可大大降低镀锌螺栓的延迟断裂倾向,但常规的去氢处理不能完全避免40Cr镀锌螺栓的延迟断裂。各种不同的淬火工艺对延迟断裂有一定的影响,但也不能解决40Cr镀锌螺栓的延迟断裂问题。低碳马氏体螺栓有很低的延迟断裂敏感性,用低碳钢或低碳合金钢制造镀锌高强度螺栓有着广泛的前景。 相似文献
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压裂泵液力端排出管汇连接螺栓在现场施工过程中发生异常断裂,通过观察和分析42CrMo双头螺栓断口的宏观及微观形貌,对其进行化学成分分析、力学性能测试、金相组织等分析断裂原因.化学成分和硬度符合要求,金相组织为回火索氏体.钢中非金属夹杂物含量低,材料纯净度良好.分析结果表明:螺栓的断裂属于疲劳断裂,疲劳起源于螺栓螺纹齿根... 相似文献
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《机械工程师》2021,(3)
某型号履带式液压挖掘机在装配过程中个别履带螺栓发生断裂。通过宏观形貌观察、扫描电镜形貌分析、能谱元素分析、金相组织检测、力学性能检测、化学成分检测等手段对螺栓断裂原因进行分析。分析结果表明,螺栓断裂模式符合氢脆断裂的典型特征。螺栓各项性能均符合标准规定,且基体残余氢含量仅为1.1×10-6,因此螺栓本身的氢脆敏感性较低。因热处理前磷化膜未去除干净,导致螺栓头下圆角表面存在深度约10μm的渗磷层。头杆连接处近表面基体的P含量异常偏高导致脆性增大,安装过程中产生微裂纹。螺栓头下圆角为应力集中区域,微裂纹加剧了应力集中状态,同时磷元素易引发氢致裂纹,促进了氢致裂纹的形成与扩展,最终表现为氢致延迟断裂。 相似文献
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本文针对某型飞机上的断裂螺栓和开裂螺栓进行了宏微观形貌分析、微区成分分析、金相组织检查及硬度测试,并进行了同批次螺栓氢含量和夹杂物测定、螺栓窝现场检查,结合断口氧化腐蚀情况获得了没有阶段性扩展痕迹、剪切唇(月牙区)等客观证据,对断裂源区的沿晶特征给出了新的解释,判断该螺栓为三向应力作用下的过载开裂. 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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Yanfei WANG Jianming GONG Yong JIANG Wenchun JIANG Wang JIANG 《Frontiers of Mechanical Engineering》2013,8(3):298
The mechanical properties and fracture behavior of 304L austenitic stainless steel after cathodic hydrogen charging and hydrogen spontaneously releasing are investigated by tensile tests. Flat tensile specimens were cathodic hydrogen charged at various current densities. For each density, two specimens were charged at the same condition. When the charging process completed, one specimen was tensile immediately to fracture and the other was aged to release the hydrogen out of it and then was also tensile to fracture. The resulting tensile properties and micrographs of fracture surfaces of these specimens were evaluated and compared. The results show ductility loss occurred in the hydrogen-charged specimens and the loss increased as the current density increasing. After hydrogen releasing, the specimens recovered a certain extent but not all of its original ductility. Scanning electron microscope (SEM) micrographs of fracture surfaces reveal that irreversible damage had developed in the hydrogen-releasing specimens during the releasing process rather than the charging process. This consequence can be ascribed to the high tensile stress caused by non-uniform hydrogen distribution during hydrogen releasing. 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
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Yong-Jun Lee Jun-Ho Park Dong-Ho Lee Sung-Su Kang 《Journal of Mechanical Science and Technology》2013,27(10):2991-2996
The purpose of this study is to investigate the effect of the changes in the tempering temperature on the hydrogen-delayed fracture resistance of high strength spring steel. The specimens with various microstructures are produced by differentiating the tempering temperature range, their mechanical characteristics are evaluated, and an impact test is carried out. The correlation with the change in mechanical properties is studied through the analysis of the microstructures with a scanning electron microscope. Hydrogen is forcefully injected inside the notched specimen electrochemically, and the hydrogen-delayed fracture resistance is evaluated using a constant loading test. The fractography of the fractured specimen is observed, and through a thermal desorption spectrometer analysis, the main trapping site of the diffusible hydrogen is investigated. The diffusible hydrogen in high strength spring steel is primarily trapped in dislocation, and the hydrogen-delayed fracture resistance increased depending on the increase in the tempering temperature. 相似文献
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