某井油管穿孔原因分析

通过宏观和微观检验、化学成分分析、力学性能测试、能谱分析等方法,对某井油管穿孔的原因进行了分析。结果表明:油管穿孔是原始缺陷形成裂纹并扩展所致。建议在油管生产过程中应严格执行有关标准和用户订货技术条件。     

HPB300钢筋表面缺陷原因分析

某HPB300钢筋表面出现了翘皮、裂纹、折叠、掉肉等缺陷,通过宏观分析、化学成分分析、金相检验、扫描电镜以及能谱分析等方法对表面缺陷形成的原因进行了分析。结果表明:大量的非金属夹杂物是造成翘皮和裂纹缺陷的主要原因,轧辊槽形状不规则是产生裂纹的另一原因;轧制过程的前面道次出现耳子或者过充满导致产生折叠缺陷;轧制过程中外界金属或其他物质落在轧件表面,在后期加工过程中又脱落形成了掉肉缺陷。     

HRB400螺纹钢表面缺陷形成原因分析

某厂生产的HRB400螺纹钢表面出现了大量的结疤和类似于"裂纹"的缺陷,通过宏观分析、化学成分分析、金相检验以及能谱分析等方法对螺纹钢表面缺陷产生的原因进行了分析。结果表明:螺纹钢表面的缺陷是由于轧制原因而造成的结疤和折叠类缺陷;另由于终轧温度较高和冷却速率较快而在螺纹钢表面形成了贝氏体组织,这也是螺纹钢生产所不允许的。     

某井114.3mm油管接箍破裂原因分析

通过化学成分分析、力学性能测试、宏观和微观检验,对某井114.3mm油管接箍破裂事故进行了调查研究。结果表明:油管接箍在工厂镀铜之前就存在原始轧制裂纹,在正常使用过程中从原始裂纹位置发生了断裂。为了防止类似事故再次发生,要求对该批油管进行返修,不允许修复油管存在裂纹、发纹、折叠等缺陷。     

发动机燃油总管分油管断裂分析

采用外观检查、金相检验、断口宏观和微观分析,对发动机燃油总管分油管断裂的原因进行了分析。结果表明:分油管的断裂均为疲劳断裂,疲劳断裂位置一般位于管子接头的焊接区域,主要原因是该区域存在露出表面的焊接缺陷和装配应力过大。     

40Cr钢产品表面裂纹产生原因分析

某公司生产的40Cr钢产品在加工过程中有时会出现表面开裂现象,采用宏观分析、金相检验以及能谱分析等方法,对不同40Cr钢产品在加工过程中出现表面裂纹的原因进行了分析。结果表明:40Cr钢产品表面裂纹的产生主要是由钢坯缺陷和轧制缺陷引起的。     

钢板表面纵向裂纹的金相检验和分析

在连铸轧制的钢板表面有沿轧制方向的裂纹。采用化学成分分析,宏、微观检验等方法对裂纹进行了分析。结果表明,裂纹中存在氧化物及其脱碳等缺陷,这说明连铸坯表面在轧制前已存在裂纹并在轧前加热中裂纹内发生氧化和脱碳,导致轧制后的钢板表面出现裂纹。     

槽钢轧制裂缝与掉块缺陷原因分析

采用低倍检验、金相检验、扫描电镜观察以及能谱分析等方法对某Q235槽钢中间坯腿部裂缝和掉块等缺陷的成因进行了分析。结果表明：由于用于轧制该槽钢的钢坯内部存在严重的中心裂纹和角部裂纹等缺陷,以及钢坯化学成分中的残余元素铜含量较高并在钢坯表面富集,是造成该槽钢中间坯腿部裂缝与掉块缺陷产生的主要原因。     

22mm厚Q235B钢板表面裂纹成因

某批规格为22 mm厚的Q235B钢板在表面质量检验过程中发现部分钢板表面存在纵向裂纹缺陷。采用光学显微镜和扫描电镜等手段对钢板表面裂纹的形成原因进行了分析。结果表明:该批钢板表面裂纹主要是由于其原始连铸板坯表面存在较深的裂纹缺陷,在后期轧制过程中被压扁、延伸,未轧合所致。     

SPHD热轧带钢边部翘皮缺陷分析

在SPHD热轧带钢边部发现有翘皮缺陷。通过宏观检验、化学成分分析、金相检验、扫描电镜及能谱分析等方法对带钢边部翘皮的原因进行了分析。结果表明:连铸时结晶器内的保护渣卷入铸坯表层,轧制变形后被拉长存在于带钢皮下表层是引起SPHD带钢翘皮缺陷的主要原因。SPHD带钢经过粗轧道次的变形,中间坯角部低温区在一定的立辊侧压作用下产生了超出板坯材料热塑性容限的变形,形成角部裂纹,这种裂纹在随后的轧制过程中不能被焊合,形成沿轧制方向断续迭层分布的翘皮缺陷,并随中间坯侧边"翻边"过程的进行向板坯上下表面翻转,最终分布在热轧板边部区域。     

某稠油井Ф88．9mm×6．45mm110EU油管挤毁原因分析

对某井在稠油开采、反注稀油过程中发生的油管挤毁和断裂事故进行了调查研究。对挤毁油管和同批新油管取样进行材质分析、尺寸测量和挤毁试验,认为油管材质和尺寸均符合标准要求。对挤毁油管外表面形状检查结果表明,油管挤毁之前没有机械损伤,油管挤毁与机械损伤无关。通过推理分析,认为油管首先发生挤毁,然后才发生断裂。通过力学分析和计算,认为油管挤毁和断裂的原因是其所受的外力超过了油管的屈服强度。     

Contact Fatigue Failure of a Tapered Roller Bearing Used in a Lorry Wheel

Tapered roller bearings, which are also known as angular-contact bearing, are suitable for supporting radial and axial loads. The more frequent types of defects in such bearings are caused by contact fatigue in these machine components, and this examination focuses on a contact fatigue failure in a tapered rolling bearing. The examination included visual inspection, microscopic analysis (optical and scanning electron microscope), and microhardness measurements. These measurements were conducted to help understand the failure mechanisms. Based on the results of visual examination and microstructure and fracture surface analysis, it was determined that the tapered roller bearing failed by contact fatigue that was caused by overloading of the bearing.     

Development of a surface defect inspection system using radiantlight from steel products in a hot rolling line

The steel industry is constantly trying to reduce production cost and improve quality by making the steel manufacturing processes continuous and faster. Currently, the rolling process of steel production is largely automated, while the finishing process is not yet appreciably automated. The finishing processes involve many tasks difficult to automate, such as defect inspection and repairing the detected defects. In recent years, however, many automated and labor-saving systems have been developed for use in the finishing processes. The surface defect inspection of steel products is the largest bottleneck in the finishing process. This paper describes an inspection system of steel surface defects for large sections, such as wide flange beams and I-beams. This system is based on applied radiant light and it senses the temperature deviation caused by defects. The wavelength of the detector is optimized to improve the signal-to-noise ratio. An optical attenuator was developed to compensate for the known temperature distribution across the product immediately after rolling. The image processor takes only 50 ms per image frame. Each time frame has the necessary image information to detect defects     

Failure analysis of pin prick defects in galvannealed sheet – A case study

A peculiar type of pin prick spots/dents on the surface of some galvannealed sheets was observed, causing significant appearance problems in the finished product. In the present study, the surface defect was characterized by visual inspection, optical microscopy, microhardness, scanning electron microscopy and EDX to understand the source and mechanism of the defects. In the visual inspection, these peculiar defects were found to align in one direction. The SEM examination exhibited three distinct regions of the surface defect apart from the matrix: (1) particle, (2) a dense layer surrounding the particle, and (3) a crater region surrounding the particle. The EDX analysis of these regions indicated enrichment of Al and Fe and depletion of Zn in the particle. The microhardness measurements of the dense layer and the matrix indicated an increase in hardness in the dense layer compared to the matrix. Based on the preliminary results, the following hypothesis was made: Dross/zinc dust falling from snout wall or intermetallic phase or reaction product particles embed in the craters on the strip surface; during subsequent skin-pass rolling these particles peel out the zinc coating in the craters, thus densifying and flattening the region surrounding the particle. The paper presents the results of the investigation.     

圆筒混料机滚圈表面点蚀及剥离失效分析

通过宏观检查、磁粉检测、化学成分分析、硬度测试以及金相检验等方法对某圆筒混料机的滚圈进行分析．找出了引起滚图表面出现点蚀及剥离的主要原因。结果表明：由于滚圈铸钢材料组织粗大．且在后续热处理过程中由于方法不当产生了魏氏组织，使得材料的力学性能较差．从而导致其在使用过程中出现点蚀及剥离等失效现象。     

Guided Wave Tuning Principles for Defect Detection in Tubing

Dispersion diagrams for longitudinal modes and several flexural modes are given. A partial loading oblique incidence technique was introduced for non-axisymmetric guided wave generation. Acoustic fields for partially loaded generation of guided waves were obtained along a sample Inconel steam generator tube surface. The axial field and the circumferential fields were non uniform. Even though the acoustic field was much more complicated than in the case of axisymmetric modes, the study of non-axisymmetric mode cannot be avoided; excitation of a single symmetric mode is often difficult due to limited access and transducer efficiency and there is also mode conversion after scattering from defects. For 100% inspection coverage of tubing and piping, three dimensional tuning (distance, frequency, and incident angle tuning), was employed. A single combination of incident angle, position, and frequency may miss defects in blind spots. However, complete inspection coverage of a whole cross sectional area over a certain distance of tubing was successfully demonstrated through a multi crack detection experiment by using the three dimensional tuning concepts. Also, the use of non-axisymmetric guided waves for a large distance inspection capability was successfully demonstrated.     

110钢级φ88.9mm×6.45mm超级13Cr钢油管刺穿失效分析

采用宏观分析、化学成分分析、力学性能测试、金相检验及扫描电镜断口分析等手段,对某油田一根规格为φ88.9mm×6.45mm的110钢级超级13Cr马氏体不锈钢油管的刺穿失效原因进行了分析。结果表明:油管失效的实质是油管发生了氯离子应力腐蚀开裂,裂纹起源于外壁腐蚀坑底部,从外壁向内壁扩展,直到穿透壁厚,形成刺穿通道,高压流体从内向外刺出并在随后的过程中形成了刺穿孔洞。     

Q235B钢热轧板带孔洞及边裂缺陷成因分析

采用宏观分析、化学成分分析、金相检验以及能谱分析等方法,对某钢铁公司生产的Q235B钢热轧板带中部孔洞和边裂缺陷的成因进行了分析。结果表明：该类热轧钢板的中部孔洞和边裂缺陷是由于连铸工艺出现异常,造成连铸板坯边部产生表层气孔以及中部产生较严重的硫偏析,从而使钢板中部生成了大量的条带状硫化物,特别是低熔点FeS的生成导致了中部孔洞缺陷的产生;而连铸板坯边部的表层气孔在轧制过程中导致了边裂缺陷的产生。     

齿轮轴裂纹分析

齿轮轴在淬火校直后表面出现轴向裂纹。采用化学成分、断口试验、热酸侵低倍试验、硬度试验和金相检验等方法对齿轮轴开裂件做了解剖分析。结果表明，齿轮轴纵向裂纹为由原材料缺陷引起的淬火裂纹，心部内裂纹为在解剖分析线切割加工过程中产生的应力裂纹。