10CrMo910 and 316 stainless steel are widely adopted in high temperature structures of power generations, chemical processing plants and petroleum refineries. In this work, a total of 10000 hour tensile creep test on ...10CrMo910 and 316 stainless steel are widely adopted in high temperature structures of power generations, chemical processing plants and petroleum refineries. In this work, a total of 10000 hour tensile creep test on 16 specimens of such two materials was conducted at 550℃. On the basis of the experimental results, the isochronous stress-strain curves and time-dependent failure assessment curves of the two materials were given. Finally, the formulae of time dependent failure assessment curve for 10CrMo910 and 316 stainless steel corresponding to long-term creep cases, which could be utilized in the high temperature defects assessment, were established. The procedure for defining the time-dependent failure assessment curves was also presented.展开更多
From the idea of failure of defective structures at high temperature beingcontrolled by two mechanisms: fast fracture due to creep crack growth initiating at the crack tipand creep rupture on the weakened section, a t...From the idea of failure of defective structures at high temperature beingcontrolled by two mechanisms: fast fracture due to creep crack growth initiating at the crack tipand creep rupture on the weakened section, a time-dependent failure assessment diagram (TDFAD) isdeveloped on the basis of the time dependent crack tip parameter J integral. According to theproposed TDFAD method, detailed crack initiation and creep crack growth analysis is avoided insafety assessments of high temperature structures by performing simple calculations of stressintensity factor and limit load. To evaluate the creep toughness parameter K_(mat), three differentexpressions are suggested on the basis of experimental load-line displacement, creep crackinitiation and growth parameters as well as the isochronous stress-strain curve. The influence ofservice factors such as temperature and service-time on the proposed TDFAD is discussed by using theproperties of 2.25CrlMo steel and an example is also presented to illustrate the approach.展开更多
基于服役30 000 h P92焊接接头610℃下高温短时力学性能试验和蠕变试验,获得了材料的稳态蠕变速率公式,并得到了相应的等时应力应变曲线。在此基础上建立了P92焊接接头时间相关失效评定图(TDFAD)。基于TDFAD分析讨论了不同应力水平下P9...基于服役30 000 h P92焊接接头610℃下高温短时力学性能试验和蠕变试验,获得了材料的稳态蠕变速率公式,并得到了相应的等时应力应变曲线。在此基础上建立了P92焊接接头时间相关失效评定图(TDFAD)。基于TDFAD分析讨论了不同应力水平下P92蒸汽管道环向外表面裂纹临界尺寸。研究发现:在较大裂纹尺寸与较低应力水平下,裂纹临界尺寸受时间影响显著;而在较大应力水平下,通用失效评定曲线(R6 option 1)与时间相关失效评定曲线(TDFAC)所确定的临界尺寸无明显差别。对长期服役于高温工况下的蒸汽管道使用TDFAC进行缺陷评定才能获得更安全的评定结果。展开更多
基金supported by the National Natural Science Foundation of China(No.50225517)the Natural Science Foundation of Shanghai(No.03ZR14022)
文摘10CrMo910 and 316 stainless steel are widely adopted in high temperature structures of power generations, chemical processing plants and petroleum refineries. In this work, a total of 10000 hour tensile creep test on 16 specimens of such two materials was conducted at 550℃. On the basis of the experimental results, the isochronous stress-strain curves and time-dependent failure assessment curves of the two materials were given. Finally, the formulae of time dependent failure assessment curve for 10CrMo910 and 316 stainless steel corresponding to long-term creep cases, which could be utilized in the high temperature defects assessment, were established. The procedure for defining the time-dependent failure assessment curves was also presented.
文摘From the idea of failure of defective structures at high temperature beingcontrolled by two mechanisms: fast fracture due to creep crack growth initiating at the crack tipand creep rupture on the weakened section, a time-dependent failure assessment diagram (TDFAD) isdeveloped on the basis of the time dependent crack tip parameter J integral. According to theproposed TDFAD method, detailed crack initiation and creep crack growth analysis is avoided insafety assessments of high temperature structures by performing simple calculations of stressintensity factor and limit load. To evaluate the creep toughness parameter K_(mat), three differentexpressions are suggested on the basis of experimental load-line displacement, creep crackinitiation and growth parameters as well as the isochronous stress-strain curve. The influence ofservice factors such as temperature and service-time on the proposed TDFAD is discussed by using theproperties of 2.25CrlMo steel and an example is also presented to illustrate the approach.
