石化装置用珠光体耐热钢损伤规律及安全评估技术的研究

【作者】 高宏波；

【导师】 赵杰； 韩双起；

【作者基本信息】 大连理工大学 ， 材料物理与化学， 2004， 硕士

【摘要】 石化装置用珠光体耐热钢一般都工作在高温压力条件下，在温度和压力长期作用下，材料的显微组织将发生一系列变化，如珠光体球化、合金元素贫化以及碳化物聚集长大等，这些组织劣化行为使得材料的高温性能下降，进而导致管材提前失效或发生爆裂事故，影响石化装置的安全运行。因而有必要研究珠光体耐热钢的损伤规律及安全评估技术。 本文主要针对石化装置常用的三种珠光体耐热钢12Cr1MoV、1Cr5Mo和20钢进行研究。通过不同温度、不同时间的高温时效试验，使材料出现不同程度的组织损伤，利用扫描电镜、电子探针、图像分析仪、光学显微镜等对时效过程中的组织演变规律进行研究。同时对于具有典型组织劣化状态的材料，进行常温、高温短时力学性能试验以及持久性能试验，以分析组织劣化对材料性能的影响。 通过上述试验，总结了三种材料在时效过程中显微组织的变化规律，并得到了碳化物的粗化动力学关系式。对材料的常温及高温短时拉伸的断口形貌分析表明，其断口都是典型的延性断口。对时效900h后的12Cr1MoV部分合金元素（Cr、Mo）的定量分析表明：Cr的贫化不显著，而Mo则有着明显的贫化现象，由于Mo的贫化，减弱了固溶强化的效果，这是材料性能降低的原因之一。 本文探讨了三种珠光体耐热钢进行剩余寿命评估的基本策略，对于在高温条件下运行的珠光体耐热钢来说，由于组织的劣化，导致持久性能的下降，这一过程可用Larson-Miller法表示为：P=Z—Z₁lg σ—Z₂σ或P=Z₀—Z—Z₁lgσ—Z₂σ，其中Z是用于表征由于组织劣化而产生的性能劣化参数，随着组织劣化，剩余寿命下降，相应的数据曲线左移，Z值随之发生变化。同时建立了材料持久性能劣化参数Z与组织劣化程度E之间的关系。因此，实现了通过对构件组织的评定来定量预测构件的剩余寿命。 本项目是与大连石化公司合作的横向课题，已于2003／12／9通过大连石化公司的验收。更多还原

【Abstract】 Pearlite heat resistant steels used in the petrochemical industry devices generally work under the high-temperature pressure condition. Under the circumstances that temperature and pressure act on for a long time, a series of changes will take place to the microstructure of the material such as pearlite spherodization, alloying elements impoverishment and carbide growing. These microstructurai degradation behavior makes high-temperature performance of material drop, leads to the pipe bursting ahead of time, and influences the safe operation of the petrochemical industry devices. Therefore it is necessary to research the damage law and security access technology of the pearlite heat resistant steels.This paper studies three pearlite heat resistant steels 12Cr1MoV , 1Cr5Mo and 20 steel which are commonly used in petrochemical industry devices. Through high-temperature aging experiment of different temperature and different time , make the microstructure damage in various degree. Microstructure changes are researched by SEM, EPMA, OM and image analyzer. At the same time, the material which has typical microstructure degradation state carries on normal temperature, high temperature short-time mechanical property experiment and creep-rupture strength experiment in order to analyse the impact of microstructure degradation on material performance.Through above-mentioned experiment, the microstructure changes law of three kinds of steels has been summarized, and kinetics formula of carbide coarsening is obtained. Tensile fractography indicates that the fracture is all typical ductility fracture. The quantitative analysis of some alloying elements (Cr , Mo ) of 12CrlMoV aging for 900 hours indicates that the impoverishment of Cr is not remarkable, but the impoverishment of Mo is obvious. Because of the impoverishment of Mo, solid solution strengthening decreases, and this is one of the reasons why material performance reduces.This paper discusses the strategy to evaluating residual life of three kinds of pearlite heat resistant steels. It has been shown that the creep-rupture strength decreased with microstructurai degradation. The relationship based on Larson-Miller method can be expressed as :P =Z -Z1lgσ - Z2 σ or P=Z0 -Z -Z1lgσ - Z2σ , where Z is a parameter related to degradation of creep-rupture strength. The residual life reduces with microstructurai degradation, and the corresponding curve moves to the left which makes Z changed. The relationship between creep-rupture strength deterioration parameter Z and microstructurai degradation parameter E is founded. So the residual life can be predicted by analyzing the microstructurai degradation of the components.This project which is the horizontal subject cooperating with Dalian Petrochemical Industry Company has already passed the confirmation on 12/9/2003.更多还原