轧机分配减速箱齿轮轴和齿轮的轮齿堆塌原因分析

轧机分配减速箱齿轮轴和齿轮在使用过程中发生轮齿堆塌而失效,通过化学成分分析、力学性能测试和金相检验等手段分析了堆塌产生的原因。结果表明:由于出现润滑故障,形成干摩擦,致使齿轮轮齿表面局部温升产生热塑流变现象,最终导致齿肉损伤,形成堆塌失效。提出防止此类失效的根本对策是防止出现供油系统故障。     

Failure Analysis of a Cylindrical Roller Bearing from a Rolling Mill

Premature failure of a cylindrical roller bearing of a gear box input shaft from a hot strip mill has been investigated. The pins of the cylindrical rollers of the bearing broke from the welded joints at their ends on the cage ring. Investigations were carried out on the failed roller pin and the welded joint. The investigation consists of visual observation, chemical analysis, characterization of macro- and microstructures, measurement of hardness profile, fractography, and energy dispersive spectroscopy (EDS). The fracture surface of the roller pins exhibits beach marks. Scanning electron microscopy (SEM) of the fracture surfaces reveals striations suggesting fatigue failure. The measured hardness profile along the welded joint shows very high hardness due to the presence of untempered martensite at the fusion boundary as revealed by the microstructural examination. Analyses of the results infer that the roller pins failed by the initiation of fatigue cracks from the welded joint because of the presence of untempered martensite originated due to improper welding process.     

热轧机轧辊失效分析及对策

Cr-Ni-Mo无限冷硬Ⅳ材料轧辊在使用中出现了工作层剥落和炸裂的现象,经现场取样分析,并在实验室进行了系列温度的时效工艺试验和耐磨性试验的基础上确定了该材料热处理条件与性能之间的关系.无限冷硬Ⅳ材料轧辊经过(425±5)℃去应力处理后,可以得到最佳性能配合和使用效果.使轧制带钢的宽度增加了10%以上,即解决了生产中的轧辊质量问题,又为用户增加产品规格提供了条件,具有推广价值.     

热轧钢管用限动芯棒表面失效形貌分析

利用数码相机、光学显微镜、扫描电镜以及能谱仪等仪器,对某参与钢管轧制后失效报废的限动芯棒进行了解剖分析,对失效芯棒的各种表面缺陷进行了观察和分类,并探讨了缺陷产生的原因。结果表明:限动芯棒经过轧制后产生的表面缺陷主要有片状脱落、网状裂纹、沟状缺陷和环状裂纹等,高温氧化和高温磨损是限动芯棒表面失效的主要原因;在轧制初期,芯棒头部和中部表面的镀铬层被磨损,随后形成氧化膜,氧化膜在压力、摩擦力及热应力的作用下发生起泡乃至开裂、脱落;裂纹首先从表面萌发,逐渐向芯棒心部扩展、交汇,在摩擦或内应力的作用下极易脱落,甚至形成大面积的严重磨损;芯棒表面的网状缺陷或大面积的氧化膜剥落进一步恶化,裂纹逐渐变宽,伴随着表层的块状脱落,形成了较深的磨损沟,并且在高温、润滑剂以及腐蚀液的作用下,沟状缺陷的内表面发生氧化,这些氧化皮的破裂和脱落加速了裂纹的扩展和局部脱落,因此当限动芯棒表面出现沟状缺陷时,意味着其失效速度将明显加快。     

基于ANSYS的四辊精密轧钢机轧辊的设计分析

通过ANSYS对3T精密轧钢机用不同直径轧辊在轧制同截面轧件轧制过程的有限元分析，揭示了在轧制过程中应力及轧制力随轧辊直径变化的分布规律，对轧辊的改进设计具有指导意义。     

基于CATIA工程斜齿圆柱齿轮精确建模与失效有限元分析

以准确绘制齿廓渐开线和螺旋线为基础,通过多截面曲面绘制出齿型曲面并运用曲面缝合功能实现齿型闭合,最后结合技术细化处理,实现斜齿轮的精确建模．在此基础上,利用CATIA软件CAE功能并结合斜齿轮传动原理,对斜齿轮实际工况进行有限元分析,从而为工程失效分析提供精确的数据参考．     

A Fault Diagnosis Expert System for a Heavy Motor Used in a Rolling Mill

A fault diagnosis expert system for a heavy motor used in a rolling mill is established in this paper.The fault diagnosis knowledge base was built,and its knowledge was represented by production rules.The knowledge base includes daily inspection system,brief diagnosis system and precise diagno-sis system.A pull-down menu was adopted for the management of the knowledge base.The system can run under the help of expert system development tools.Practical examples show that the expert system can diagnose faults rapidly and precisely.     

加热炉不锈钢盘管泄漏失效分析

某气田再生气加热炉奥氏体不锈钢盘管在运行49h后发生泄漏,采用化学成分分析、力学性能测试、渗透检测、宏微观形貌分析、晶间腐蚀试验以及能谱分析等方法对盘管失效原因进行了分析。结果表明：由于进入加热炉盘管的介质中含有较高浓度的氯离子,导致盘管发生了氯化物应力腐蚀开裂。并提出了相应的防护措施。     

变速箱双联齿和512齿轮失效分析

某型号变速箱在台架试验过程中,双联齿和与之啮合的512齿轮均发生失效事件。采用断口分析、金相检验、硬度测试以及化学成分分析等方法对失效件进行了检验。结果表明:由于双联齿和512齿轮的齿面存在严重的异常接触,加之双联齿的有效硬化层深度和心部硬度均低于技术要求,从而导致在台架试验过程中双联齿表面发生严重的接触疲劳剥落,与之啮合的512齿轮发生弯曲疲劳断齿。     

Cracking Failure of Hardfacing Layer of Repaired Backup-Roller in Rolling Mill

A worn backup-roller in rolling mill was repaired by hardfacing technology. The routine flaw detection after machining revealed that randomly distributed circumferential short cracks occurred on the surface of repaired roller. Sectional observation throughout hardfacing region showed that intensively distributed transverse short cracks were also present inside the outer layer of hardfacing region. Detailed metallographic analysis and fractographic investigation indicate that the transverse short cracks are crystallization cracks, caused by hot-cracking. General excessive element of P in the outer layer and the segregation of impurity elements P, S within the interdendritic space and at the grain boundary are metallurgical factors responsible for hot-cracking. Occurrence of the bending load on the roller, resulting from the great self-weight of roller, is mechanical factor leading to forming transverse crystallization cracks.     

齿轮轴失效分析

对失效齿轮轴进行了断口的宏观检查、金相检验、断口扫描电镜分析,结果表明残余拉应力是齿轮轴开裂的主要原因,聚集的非金属夹杂物和混晶对开裂有重要的促进作用.     

小螺旋锥齿轮断裂失效分析

对小螺旋锥齿轮的断裂失效进行了分析，结果表明，齿轮在传动中出现偏载，造成了连续冲击过载，而使齿轮过早疲劳断裂，本文还讨论了造成偏载的可能性。     

Failure Analysis of Stainless Steel Pipeline Used in Propulsion Engine Test Facility

Austenitic stainless steel pipelines are used as a conduit for gaseous nitrogen to ejector flow lines of propulsion engine test facility. Leakage was noticed near a welded T-joint of such a pipeline system that was in service for years. Detailed metallurgical investigations were carried out to understand the cause of failure. Synergistic effect of chloride ions, thermal stresses from welding, and the presence of sensitized grains of the material led to stress-corrosion cracking of the steel. This paper highlights details of investigation.     

Failure Analysis of SG Iron Collector Nozzle Holder Used in Steel Ladle

The failed collector nozzle holder (CNH) of steel ladle, made of ferrite grade spheroidal graphitic (SG) iron was investigated in the present article. The microstructure, volume fraction, and morphology of spheroidal graphite were investigated. The cause of failure was analyzed through comparative study with a good CNH, using optical and scanning electron microscopy and the data available in various sources in the literature. The effect of microstructure evolution on mechanical properties of the SG iron was analyzed. Failure analysis conducted in this article revealed that the presence of exploded and chunky graphite succeeded the distortion caused by dimensional instability at elevated temperature. The phenomena analyzed were found to be aggravated at higher carbon equivalent, lower residual magnesium, and low yield strength of the sample. The remedial measures were suggested in material and operation guidelines for failure prevention of CNH in steel ladles.     

Study on Rolling Mill Gear Box and Design of Multichannel Fault Diagnosis

Gear box places an important role rolling mill.Its reliability decides the machine operation.Due to the important role,if the key machine is broken because of g...     

风机齿轮箱齿轮失效分析

某发电厂的风力发电机在运行中齿轮箱出现故障,经现场检查发现在风机某一级传动齿轮中有一个齿轮出现断齿现象,断裂部位在轮齿的中间腰部位置.为了判断风机齿轮箱的断裂性质及原因,对风机齿轮箱断齿残片进行了宏微观观察,对断齿残片基体及断口源区进行了能谱分析,测定了断齿表面残余应力,还对齿轮进行了断口定量分析.结果表明,风机齿轮箱齿轮轮齿失效性质为弯曲疲劳断裂.可基本排除齿轮设计、材质、使用维护方面的异常,齿轮断裂原因在于断裂部位存在夹渣缺陷.     

齿轮开裂失效分析

采用断口分析、化学成分分析、低倍检验、金相检验和硬度测试等方法对某批经渗碳、淬火热处理及磨齿加工后放置一段时间发生开裂的齿轮的失效原因进行分析。结果表明：齿轮渗碳层碳化物级别过高,加上淬火后齿轮齿部应力集中,磨齿时又产生磨削裂纹,齿轮在放置期间由于应力导致裂纹扩展而开裂。     

Failure Analysis of Two Stainless Steel Based Components Used in an Oil Refinery

The petroleum industry has changed significantly over the past decades. For example, in Brazil, oil extraction under very deep sea water is growing very quickly. As a consequence, materials and components used for such applications must have properties required to withstand adverse conditions and ensure satisfactory performance and reliability in service. Nonetheless, components that normally fulfill these standard requirements can fail under severe service conditions such as high pressure and temperatures and high concentrations of H₂S and CO₂. Among the factors that can cause the premature failure in metallic components are the use of inadequate materials, the presence of defects that appeared during the production, and errors of project, assembly, or maintenance. Failure analysis allows the identification of causes and thus contributes to improvements in the operation and performance of similar equipment. In this work, light optical microscopy and scanning electron microscopy (SEM) were used to analyze the microstructure and fracture surface of two centrifugal pump shafts that failed during use in a Brazilian petroleum refinery. The results showed that one shaft, made of duplex stainless steel, failed by fatigue fracture, and the other, made of 316 austenitic stainless steel, experienced a similar fracture, which was promoted by the presence of nonmetallic inclusion particles.     

大型齿轮箱输出轴断裂失效分析

利用金相检查、SEM分析和X射线衍射物相分析等方法对材料为42CrMo的开裂大型齿轮箱输出轴进行失效分析,结果表明残余拉应力和位于中心的严重的冶金缺陷是输出轴失效的原因.     

Failure Analysis of Gearbox and Clutch Shaft from a Marine Engine

This article presents metallurgical failure analysis of a gearbox shaft and a clutch shaft from a marine engine. The gearbox shaft was made of low alloy steel, and the clutch shafts were components made of carbon steel. Fracture surface examination revealed circumferential ratchet marks with the presence of inward progressive beach marks suggesting rotary-bending fatigue failure in the case of gearbox shaft. The star-shaped pattern on the clutch shaft fracture surface suggested that the failure was due to torsional overloading which might have initiated at corrosion pits visible around the fracture surface. The gearbox shaft experienced rotational bending stresses which induced fatigue failure because the fatigue strength of the alloy was too low. The fatigue failure of the gearbox shaft led to the torsional failure of the corroded clutch shaft. The sudden, high level failure load on the clutch shaft occurred when the gear box shaft failed.