【作者】 张忠政；

【导师】 巩建鸣；

【作者基本信息】 南京工业大学 ， 安全技术及工程， 2005， 硕士

【摘要】 由于不锈钢优良的机械性能和良好的抗氢脆性,在石油化工等部门得到大量应用。不锈钢长期在高温高压临氢环境下服役,其损伤与断裂对于石化企业的安全生产是至关重要的。本文主要针对扬子石化芳烃厂服役了10 万小时的循环氢气加热炉炉管出口段进行研究,通过炉管材料Incoloy 800H 的微观组织检查和常温以及高温机械性能试验,研究分析炉管材料微观组织结构损伤和机械性能劣化,讨论损伤的原因; 通过高温下断裂韧性试验,研究服役炉管断裂性能,并根据机械性能试验和断裂韧性研究结果建立高温失效评定图,对工程案例进行安全评定。本文的主要研究工作和结论如下: (1) 通过微观组织检查,研究炉管微观组织沿轴向和径向的变化以及损伤分布情况。对于服役10 万小时的Incoloy800H 炉管,其微观组织结构发生了一定程度的损伤,但并不严重。未观察到氢对微观组织结构损伤的明显特征,表明高温高压临氢条件下,Incoloy 800H 材料微观结构对于氢损伤不敏感。(2) 通过Incoloy800H 炉管的常温和高温机械性能试验研究,结果表明服役10万小时的炉管机械性能已经发生了某种程度下降,其中高温下塑性下降较为明显。在炉管焊接部位,常温冲击韧性较低,高温塑性下降较大,表明焊接部位已经发生一定脆化,是炉管中较为薄弱的部位。与新材料相比,尽管机械性能有些下降,但服役炉管仍有较高地强度和韧性,具有一定的安全储备。(3) 根据炉管材料在680℃下的蠕变和持久试验数据,利用Larson-Miller 寿命外推方法,预测服役条件下炉管的剩余寿命大约在10 万小时左右。通过分析比较炉管机械性能劣化程度,认为材质劣化主要原因是温度和压力等因素造成,氢对机械性能劣化影响不大。(4) 通过高温断裂韧性的试验研究,测得了Incoloy800H 在680℃高温下断裂韧性,结果表明温度高的部位的断裂韧性值低,总体上服役10 万小时的Incoloy800H炉管具有较强的抵抗裂纹扩展能力。论文就影响高温断裂韧性测试的因素进行了分析。(5) 根据试验测得炉管机械性能数据,建立了服役10 万小时的Incoloy800H 材更多还原

【Abstract】 The stainless steels are used widely in petroleum and chemical industry because of its excellent mechanical properties and hydrogen embitterment resistant abilities. The damage and fracture of stainless steel serviced in hydrogen environment with high temperature and pressure are very important for the safety production of petroleum and chemical industries. In the present paper, damage and fracture of the furnace tube used to heating hydrogen circularly, which had served for 106 hours, were mainly studied. The microstructure degradation of Incoloy800H furnace tube was analyzed by use of metallurgical examination, and the change of mechanical properties at room temperature and high temperature was investigated by mechanical tests. The reasons of resulting in damage of the furnace tube serviced in the hydrogen environment with high temperature and pressure were discussed. The fracture properties of the furnace tube are studied by measuring the high temperature fracture toughness of Incoloy800H alloy. According to obtained mechanical properties and fracture toughness of material , the high failure assessment diagram of the Incoloy800H furnace tube serviced for 106 hr at 6800C was constructed, which was applied in practical engineering case. The major research works and conclusions of this paper are as follows: (1) The change of the microstructure and damage distribution of the serviced furnace tube along axial and radial direction were analyzed by metallurgical examination. Little damage occurs in a certain extent for the Incoloy800H furnace tube serviced for 106 hr in the hydrogen environment with high temperature and pressure. The microstructure feature of the hydrogen damage was not observed, which implies that the Incoloy800H alloy is not susceptive of hydrogen damage. (2) Mechanical property tests of Incoloy800H furnace tube were carried out at room temperature and high temperature. The research results show that the mechanical properties of serviced Incoloy800H tube have be somewhat degraded. The decrease in plasticity is obvious at elevated temperature. Especially for weldment of the furnace tube, its impact toughness is relatively small in the room temperature, and the plasticity obviously falls down,which implies that the weldment become brittle in some extent and will be one of the weak links. Compared that new material, the mechanical properties of the serviced furnace tube decrease. However, the serviced Incoloy800H furnace tube still retain higher strength and toughness and has some safety stock. (3) Based on the data of creep test and long term term, the remaining life of the Incoloy800H furnace tube is predicted by Larson Miller life extrapolation methods and is about 106 hours at operating condition. By comparing and analyzing the degradation extent of the mechanical properties of the serviced furnace tube, such conclusions are obtained that the temperature and pressure are the main factors of causing mechanical property degradation of the Incoloy800H furnace tube and the effect of hydrogen on its mechanical properties is low. (4) By performing high temperature fracture toughness test, the fracture toughness of the serviced Incoloy800H alloy was measured at 680℃. The test results indicate that the fracture toughness is lower at higher temperature zone of the furnace tube. In general, the serviced Incoloy800H furnace tube still has the excellent ability of resisting the crack growth. The influencing factors of measurement of elevated temperature fracture toughness were also discussed in this paper. (5) Based on the mechanical property data of Incoloy 800H obtained from test, high temperature failure assessment diagram of the Incoloy800H alloy serviced for 106 hr was constructed. It was successfully applied to the elevated temperature fracture safety assessment for the Incoloy800H furnace tube with defects, and the safety assessment result indicates the furnace tube with some defects is safe at assessment condition.更多还原