金属材料高温蠕变—疲劳损伤研究进展

用于汽轮机转子或涡轮叶片的金属材料长时间在高温环境下受到交变载荷的作用,会发生严重的高温蠕变—疲劳损伤,从而降低了转子及叶片的使用寿命。文中分析了加载条件因素、环境因素、材料特性及热处理工艺等对汽轮机转子钢蠕变—疲劳裂纹形成及扩展的影响,从疲劳裂纹萌生原因、蠕变阶段材料的组织变化及疲劳—蠕变的交互作用综述了汽轮机转子钢疲劳蠕变的损伤机理;并指出以材料的蠕变疲劳损伤机理为基础,建立材料的本构关系及损伤演化方程,将是高温疲劳—蠕变损伤研究的重点。     

基于遗传规划方法的汽轮机转子钢热脆化性能预测

在汽轮机转子钢热脆性无损检测技术的开发中,将遗传规划法应用到30Cr2MoV钢韧脆性转变温度预测模型的建立中,以提高检测精度。把材料的脆性转变温度作为预测模型的因变量,将单环动电位再活化法测得的峰值电流密度、电解液温度、材料的化学成分参数(J参数)、材料中Cr质量分数、S质量分数、材料的维氏硬度和晶粒度作为自变量,将因变量和自变量的试验测定结果分为训练样本数据和检验样本数据。依据训练样本数据,经过遗传规划法求得最优预测模型,并用检验样本数据对所得的预测模型进行检验。结果表明：所得模型的预测误差为±20 ℃,精度较高。因此可以将遗传规划法应用到汽轮机转子钢预测模型的建立中。     

汽轮机转子的模态分析与动力特性分析

详细介绍了汽轮机转子的建模思路与简化环节,利用ANSYS软件对汽轮机转子进行了模态分析,对汽轮机转子模型进行了动力特性分析,为研究和解决汽轮机转子故障提供理论指导。     

亚临界汽轮机转子的寿命计算

针对国产亚临界汽轮机,对其转子的寿命进行了分析研究,讨论了对汽轮机转子寿命有重要影响的因素,并给出了汽轮机转子温度场和应力以及转子使用寿命的计算方法。研究结果对实现汽轮机转子寿命的科学管理和优化分配具有一定的指导意义。     

数控汽轮机转子轮槽中心支架介绍

通过对汽轮机转子的加工制造图纸及实际工况研究,设计了用于加工汽轮机转子轮槽的支撑和分度用数控汽轮机转子轮槽中心支架,使汽轮机转子转槽中心支架的加工精度及效率大大提高。     

超临界汽轮机转子应力集中区域优化

转子作为汽轮机最重要的部件,在高温、高压等恶劣环境下,在转子应力集中区域,蠕变脆性断裂的危险性增大,这势必会造成转子寿命的损耗,进而缩短汽轮机的使用寿命。以超临界汽轮机高压转子作为研究对象,将转子寿命设为目标函数,对转子应力集中区域尺寸进行优化。运用热应力分析理论,针对应力集中区域在ANSYS软件中使用遗传算法来对转子形状进行优化,降低转子应力使得汽轮机运行更安全、可靠。     

核电汽轮机转子在低周疲劳与高周疲劳交互作用下裂纹扩展寿命的研究

提出核电汽轮机转子在低周疲劳与高周疲劳交互作用下裂纹扩展寿命的计算与评定方法。介绍核电汽轮机转子的低周疲劳与高周疲劳的应力幅与应力范围、低周疲劳裂纹扩展寿命与高周疲劳扩展寿命的计算方法。给出了核电汽轮机转子在低周疲劳与高周疲劳交互作用下裂纹扩展日历寿命的计算与评定方法,以及1 000 MW级核电汽轮机焊接低压转子疲劳裂纹扩展日历寿命的计算与改进的应用实例。结果表明,高周疲劳对汽轮机转子疲劳裂纹扩展日历寿命有比较大的影响,新研制核电汽轮机的转子结构设计和在役核电汽轮机的转子安全性评定,需要评估转子在低周疲劳与高周疲劳交互作用下裂纹扩展 寿命。     

浅谈汽轮机转子弯曲变形原因分析及修复方法与预防

本文针对汽轮机转子弯曲变形问题进行分析,找出了汽轮机转子弯曲变形的原因,进而采取有效的方法修复汽轮机转子,以便汽轮机及时投入生产使用。通过采取有效的防范措施,避免汽轮机在开停车和运行过程中发生转子变形事故。     

汽轮机转子加工工艺分析

汽轮机转子是汽轮机的关键部件,其结构很复杂,且尺寸精度和跳动要求很高,加工难度较大,依据汽轮机转子结构和工艺特点,阐述了汽轮机转子的装夹方法,对汽轮机转子叶根槽及轴颈和推力面关键结构的加工工艺进行分析研究,并针对在加工过程中产生的问题提出了合理的加工方法,从而保证了转子的加工精度和表面粗糙度要求。     

工业汽轮机转子用钢28CrMoNiV脆性转变温度的研究

针对如何正确评定工业汽轮机转子用钢28CrMoNiV的脆性转变温度(fracture appearance transition temperature,FATT)的问题,通过系列温度冲击法测定了该转子钢的冲击吸收功、脆性断面率,利用扫描电镜(scanning electronic microscopy,SEM)对冲击试样断口形貌的变化进行了研究,结合Boltzmann函数对冲击试验结果的拟合分析,正确评定了该转子钢的FATT。并对影响FATT的因素进行了归纳,研究分析了化学成分、微观组织和晶粒尺寸对转子钢FATT的影响。研究结果表明,28CrMoNiV钢的断口形貌随着温度的降低由韧窝逐渐向解理断裂变化,该转子钢的FATT为-52℃,明显低于技术标准要求值(≤85℃);通过先进的冶炼技术和热加工工艺严格控制化学成分,获得晶粒细小均匀的回火索氏体组织以及针状铁素体内部的高密度位错和亚晶界结构,可以提高转子钢的冲击韧性及降低FATT。     

25 Cr2 Ni2 MoV 钢焊接接头低周疲劳性能研究

对新型汽轮机焊接转子材料25Cr2Ni2MoV焊接接头及其母材进行应变控制的低周疲劳试验,并进行了相应的断裂位置统计和循环变形特征分析。试验结果表明,焊接削弱了焊接接头的疲劳强度,受到结构非均匀性和各部分力学性能的相对不匹配等因素的影响,焊接接头的断裂位置体现出明显的应变水平依赖性;焊接接头和母材在循环变形过程中均表现出循环软化特性,且存在明显的拉压不对称性,拉压不对称程度随应变水平的增加而增加;与母材相比,焊接接头表现出更加明显的平均应力松弛现象,且平均应力绝对值随着循环周次不断减小最后趋于常值。     

Evaluation of fracture toughness degradation of CrMoV rotor steels based on ultrasonic nonlinearity measurements

The objective of this paper is to develop a nondestructive method for estimating the fracture toughness (K _IC) of CrMoV steels used as the rotor material of steam turbines in power plants. To achieve this objective, a number of CrMoV steel samples were heat-treated, and the fracture appearance transition temperature (FATT) was determined as a function of aging time. Nonlinear ultrasonics was employed as the theoretical basis to explain the harmonic generation in a damaged material, and the nonlinearity parameter of the second harmonic wave was the experimental measure used to be correlated to the fracture toughness of the rotor steel. The nondestructive procedure for estimating theK _IC consists of two steps. First, the correlations between the nonlinearity parameter and the FATT are sought. The FATT values are then used to estimateK _IC, using theK _IC versus excess temperature (i.e.,T-FATT) correlation that is available in the literature for CrMoV rotor steel.     

高炉煤气能量回收透平转子二级叶片失效分析

对某公司断裂失效的高炉煤气能量回收透平转子二级叶片的宏观形貌、化学成分、硬度、断口、显微组织进行了观察和分析,以找出其失效的原因。结果表明:叶片断裂属于疲劳断裂,疲劳裂纹起始于叶片进气边;叶片断裂的原因为所用材料与常规设计材料不同,且采取的热处理工艺不当;叶片表面由颗粒冲蚀产生的大量凹坑促进了疲劳裂纹的萌生,是疲劳裂纹形成的外因。     

A study on fracture surface of aged turbine rotor steel by fractal dimension

Since fracture surface presents clear evidence to describe the circumstances of material failure event, analysis of fracture surface should provide plenty of useful information for failure prevention. Thus if we extract proper information from the fracture surface, the safety evaluation for plant component could be more accurate. In general, the chaotic morphology of fracture surface is determined by the degree of material degradation as well as by other factors such as type of load, geometry of specimen, notch condition, microstructure of material and environment. In this research, we developed a fractal analysis technology for the fracture surface of aged turbine rotor steel based on the slit-island technique using an image analyzer. Moreover the correlation between the fractal dimension and the aging time was studied.     

AP1000核电汽轮机转子疲劳断裂分析

针对核电汽轮机转子疲劳断裂进行分析,分别对高周疲劳以及低周疲劳引起的转子断裂进行分析。分析表明：除了破坏性超速原因,无论是低周疲劳还是高周疲劳均不会导致低压整锻转子产生断裂。     

汽轮机低压转子2Cr13不锈钢叶片断裂分析

通过断口宏观形态分析、扫描电镜(SEM)微观观察、能谱(EDS)分析和显微组织分析以及常规力学性能测试,对电站汽轮机低压转子2Cr13不锈钢叶片断裂失效模式和失效原因进行了全面的分析,并对开裂机制进行了深入探讨.结果表明:该汽轮机低压转子2Cr13不锈钢叶片的失效模式为腐蚀疲劳破坏,叶片材质较差的内部因素和腐蚀疲劳的工况条件共同作用造成了叶片的断裂失效.     

Evaluation of the influence of the initial deflection curve shape of a two-span rotor with residual imbalance on its vibroactivity during rundown

This work is devoted to the evaluation of the influence of the curve shape of the ineradicable initial deflection of a two-span rotor with the residual imbalance on the transition vibration amplitudes at low critical speeds under the rundown. The model corresponds to a high-pressure rotor–combined mid-low-pressure rotor (HPR–MLPR) system of a turbine unit. It is assumed that rotors are connected by a rigid coupling and installed on anisotropic elastic damper supports. It is supposed that the resulting deflection (bend) of this system is formed as a result of the fact that a high-pressure rotor acquires the initial deflection during the operation or because of abnormal launch conditions, the curve shape of which for a load-free rotor is known. The influence of the mutual arrangement of the residual imbalances of rotors and the imbalances caused by the resulting deflection of shafting in a system on the amplitudes of its transition vibration under the rundown of a turbine unit has been studied for two shapes of the initial rotor deflection curve that have the highest and lowest values of the shape parameter. The values of the initial rotor bending deflection and the residual imbalance of both rotors have been set equal to the maximum acceptable values for the operation of a turbine unit. Amplitude calculations have been performed for rotors of a K-300-23.5 Leningrad Mechanical plant (LMZ) turbine.     

2.25Cr-1Mo钢回火脆化对氢脆的影响

用冲击试验和电化学充氢方法研究了长期服役的2．25Cr-1Mo钢的回火脆化和氢脆问题．并对试样进行了显微组织分析和断口电镜扫描。结果表明：回火脆化程度不高的母材对氢脆的影响较小，断口形貌为准解理和少量的沿晶断裂；回火脆化程度较严重的焊缝对氢脆的影响较大，断口形貌为沿晶断裂。对于母材．回火脆化与氢脆的关系为线性相加；对于焊缝，回火脆化大大加剧了氢脆的程度。     

对转涡轮低压转子叶片的流固耦合数值分析

采用对转涡轮设计能提高航空涡轮发动机性能,其中无导叶方案是发展趋势之一。在无导叶对转涡轮中,低压转子叶片受到较大的高压转子出口气流激励。基于ANSYS/CFX软件,采用流固耦合数值分析方法对低压涡轮转子叶片进行了分析,得到了高压涡轮转子叶片尾流作用下的低压涡轮转子叶片振动的应力和变形变化规律。叶片温度对振动应力和位移的平均值、幅值和周期的影响较大,叶片材料密度对振动周期产生明显的影响,高低压转叶轴向间距的选择应兼顾涡轮效率等因素。