连铸坯轧制的Q235厚板质量分析

对Q235厚板出现的表面裂纹进行的检验确认裂纹源自于连铸板坯。进一步的检查表明，钢中硫化物等夹杂物及其偏析是造成铸坯表面裂纹及板材性能缺陷的主要原因。建议改善钢液清洁度和改进连铸工艺为解决途径。     

液化石油气储罐焊疤表面裂纹的磁记忆信号研究

采用磁记忆检测发现液化石油气储罐焊疤部位存在较强的磁记忆信号。通过对储罐进行0～4．0MPa的加载试验，研究磁记忆信号的幅度和梯度随载荷的变化。最后采用磁粉探伤复验发现磁记忆信号部位存在大量3-5mm长的焊疤表面裂纹。试验结果表明，在0～2．0MPa的加压过程中，磁记忆信号的幅度和梯度均逐渐增大，到2．0MPa时达到峰值，在2．0～4．0MPa的加载过程中迅速下降，在此期间采用声发射监测，发现了七个声发射信号，证明该部位应力产生了迅速释放。由此证明磁记忆信号的幅度和梯度既与材料所处的整体应力有关，也与该部位的局部应力集中度有关。     

Analysis of free and forced vibration of a cracked cantilever beam

Structures are weakened by cracks. When the crack size increases in course of time, the structure becomes weaker than its previous condition. Finally, the structure may breakdown due to a minute crack. Therefore, crack detection and classification is a very important issue. In this study, free and forced vibration analysis of a cracked beam were performed in order to identify the crack in a cantilever beam. Single- and two-edge cracks were evaluated. The study results suggest that free vibration analysis provides suitable information for the detection of single and two cracks, whereas forced vibration can detect only the single crack condition. However, dynamic response of the forced vibration better describes changes in crack depth and location than the free vibration in which the difference between natural frequencies corresponding to a change in crack depth and location only is a minor effect.     

压力容器壳体胶结补强后的裂尖应力场

本文从中心穿透裂纹板的局部范围胶结补强问题着手,研究了压力容器壳体上的裂纹在胶结补强后的裂纹尖端应力场,给出了裂尖应力分布曲线。证明补强后裂尖应力比未补强时明显减小,补块尺寸也对补强效果有很大影响。     

抽油杆的涡流探伤

介绍双通道涡流探伤仪组成的抽油杆无损探伤系统,根据抽油杆检测的特殊性在探伤系统中引入一个特殊的接口设备,用于完成检测探头的信号分配、预处理及系统控制。     

自增强厚壁筒表面裂纹尖端应力强度因子的柔度标定法

采用柔度法对液压疲劳实验中的自增强厚壁筒表面裂纹尖端应力强度因子进行了标定,结果表明这是一种求得表面裂纹尖端应力强度因子的有效方法。     

A study on tensile and fatigue properties of aged NAS 254N stainless steel at elevated temperatures

The effects of aging on tensile properties and fatigue crack growth behaviors of NAS 254N stainless steel was studied. Yield strength and ultimate tensile strength of the aged specimens were almost the same as the as-received (as-rec.). The fracture strain, however, was decreased significantly by the aging, and the fracture surface of the aged at room temperature (RT) test was intergranular. As test temperature increased, yield strength, ultimate tensile strength and elongation decreased. And a type of serration was observed at 550-650°C As strain rate decreased, yield strength and ultimate tensile strength decreased, but elongation increased. It was observed that tensile strength and strain had a sudden change at one point. And this critical temperatureT _cr was 550°C. The effect of aging time on the tensile strength and strain was also investigated. Tensile strength and strain decreased significantly beyond 100hrs. Fatigue crack growth rate at RT was enhanced by the aging at high stress intensity factor range. This is due to the occurrence of the intergranular fracture in the aged specimen. At 650°C, the fatigue crack growth behavior was almost the same without intergranular fracture.     

腐蚀疲劳裂缝扩展的韧带模型

采用４３４０、１５和Ａ５０８三种结构钢,八种热处理状态;测定了它们在空气、海水和蒸馏水中的疲劳、应力腐蚀和腐蚀疲劳裂缝扩展速率,并进行了定量断口分析。在比较了叠加模型、竞争模型与实验结果的差异之后,提出了腐蚀疲劳裂缝扩展的韧带模型,拟出了该模型的计算程序。结果表明,尽管这个模型还比较粗糙,某些常数的决定还有点勉强,但由此估算的腐蚀疲劳扩展曲线,无论在形状和数值上,都与实验吻合;而它的简单方便,为工程应用提供了有利条件。     

原地浸出的矿岩结构演化机理研究

原地浸出中矿岩结构演化是一个受多因素耦合作用的复杂动力学过程。本文对原地浸出作业中矿岩裂纹扩展与破坏机理进行了较详细的理论分析,发现了渗流水楔作用是矿岩裂纹产生、扩展及贯通的重要原因。在理论分析的基础上,建立了原地浸出矿岩结构演化的数学模型,对于缩短生产周期、提高浸出速率和提高经济效益具有一定的意义。     

加氢装置中管道法兰密封钢圈的断裂分析

采用宏观及断口分析、金相与硬度检测、扫描电镜与能谱分析等方法,对加氢装置中管道法兰密封钢圈的断裂原因进行了分析。结果表明,断裂是由于管道中气体所含的H2S对钢圈内表面产生严重点蚀和钢圈组织不合理所致。当法兰螺栓紧固时,钢圈内表面所受的强大拉应力造成蚀坑底部的应力集中而形成裂纹源,而钢圈硬脆的淬火组织促进了裂纹在基体中的快速扩展,最终导致断裂。