高强度螺栓发生氢脆(hydrogen embrittlement,HE)和应力腐蚀(stress corrosion,SCC)事件直接威胁核电厂安全运行。该文介绍国内核电厂高强度螺栓HE和SCC问题现状,分析了失效机理、规律和控制难点,给出对策建议。在2015—2019这5年时间里...高强度螺栓发生氢脆(hydrogen embrittlement,HE)和应力腐蚀(stress corrosion,SCC)事件直接威胁核电厂安全运行。该文介绍国内核电厂高强度螺栓HE和SCC问题现状,分析了失效机理、规律和控制难点,给出对策建议。在2015—2019这5年时间里,国内核电厂共发生了 22起高强度螺栓HE和SCC事件,其中,内氢脆(internal hydrogenembrittlement,IHE)、阳极溶解型应力腐蚀(anode dissolution type of stress corrosion cracking,AD-SCC)和氢脆型应力腐蚀(hydrogen embrittlement type of stress corrosion cracking,HE-SCC)事件分别占比18%、27%和55%,与强度过高有关的事件占比55%。HE和SCC问题与时间高度关联,具有明显的慢性、偶发和随机性特征,已经成为国内核电厂高强度螺栓安全服役的主要威胁,应引起监管部门关注。长远看,建立针对高强度螺栓HE和SCC问题的行业标准、研究和使用可以有效阻断腐蚀介质到达螺栓表面的新方法、开发新型抗HE和SCC的高强度螺栓,是治理该问题的长久之策。展开更多
The hydrogen permeation behavior and stress corrosion cracking （SCC） susceptibility of precharged 7075-T6 A1 alloy were inves- tigated in this paper. Devanthan-Stachurski （D-S） cell tests were used to measure the ...The hydrogen permeation behavior and stress corrosion cracking （SCC） susceptibility of precharged 7075-T6 A1 alloy were inves- tigated in this paper. Devanthan-Stachurski （D-S） cell tests were used to measure the apparent hydrogen diffusivity and hydrogen permeation current density of specimens immersed in 3.5wt% NaCl solution. Electrochemical experiment results show that the SCC susceptibility is low during anodic polarization. Both corrosion pits and hydrogen-induced cracking are evident in scanning electron microscope images after the specimens have been charging for 24 h.展开更多
Variation and degradation of P-110 casing steel mechanical properties, due to sulfide stress cracking （SSC） in sour environments, was investigated using tensile and impact tests. These tests were carried out on spec...Variation and degradation of P-110 casing steel mechanical properties, due to sulfide stress cracking （SSC） in sour environments, was investigated using tensile and impact tests. These tests were carried out on specimens, which were pretreated under the following conditions for 168 hours： temperature, 60 ℃; pressure, 10 MPa; H2S partial pressure, 1 MPa and CO2 partial pressure, 1 MPa; preload stress, 80% of the yield strength （os）; medium, simulated formation water. The reduction in tensile and impact strengths for P-110 casing specimens in corrosive environments were 28% and 54%, respectively. The surface morphology analysis indicated that surface damage and uniform plastic deformation occurred as a result of strain aging. Impact toughness of the casing decreased significantly and intergranular cracking occurred when specimens were maintained at a high stress level of 85% %.展开更多
一批在生产加工后进行了淬火和低温回火的齿轮在库房存放过程中发生开裂。通过超声波探伤、金相检验、化学成分分析、硬度测试、断口形貌观察、端淬试验和补充热处理等手段,对齿轮开裂原因进行了分析。结果表明,开裂齿轮强度高导致氢脆...一批在生产加工后进行了淬火和低温回火的齿轮在库房存放过程中发生开裂。通过超声波探伤、金相检验、化学成分分析、硬度测试、断口形貌观察、端淬试验和补充热处理等手段,对齿轮开裂原因进行了分析。结果表明,开裂齿轮强度高导致氢脆敏感性高,在次表面产生氢致延迟裂纹是引起齿轮快速脆性开裂的直接原因。开裂齿轮淬硬性和淬透性过高,超出了BS EN 10084-2008对18CrNiMo7-6+HH钢淬透性要求,是齿轮开裂的根本原因;通过调整淬火介质,降低淬火时高温区冷速,从而降低淬回火后齿轮的强度和硬度,可有效避免开裂。展开更多
The role of atomic hydrogen and hydrogen-induced martensites in hydrogen embrittlement in slow strain rate tensile tests and hydrogen-induced delayed cracking (HIC) in sustained load tests for type 304 L stainless ste...The role of atomic hydrogen and hydrogen-induced martensites in hydrogen embrittlement in slow strain rate tensile tests and hydrogen-induced delayed cracking (HIC) in sustained load tests for type 304 L stainless steel was quantitatively studied. The results indicated that hydrogen-induced martensites formed when hydrogen concentration C 0 exceeded 30 ppm, and increased with an increase in C 0, i.e. M(vol%)=62–82.5 exp (?C 0/102). The relative plasticity loss caused by the martensites increased linearly with increasing amount of the martensites, i.e. l δ(M), %=0.45 M (vol %)=27.9?37.1 exp(?C0/102). The plasticity loss caused by atomic hydrogen l δ(H) increased with an increase in C 0 and reached a saturation value l δ(H)max=40% when C 0>100 ppm. l δ(H) decreased with an increase in strain rate $\dot \varepsilon $ , i.e. l δ(H), $\% = - 21.9 - 9.9\dot \varepsilon $ , and was zero when $\dot \varepsilon \geqslant \dot \varepsilon _c = 0.032/s$ . HIC under sustained load was due to atomic hydrogen, and the threshold stress intensity for HIC decreased linearly with in C 0, i.e. K IH (Mpam1/2)=91.7?10.1 In C 0 (ppm). The fracture surface of HIC was dimple if K 1 was high or/and C 0 was low, otherwise it was quasi-cleavage. The boundary line between ductile and brittle fracture surface was K 1-54+25exp(?C 0/153)=0.展开更多
文摘高强度螺栓发生氢脆(hydrogen embrittlement,HE)和应力腐蚀(stress corrosion,SCC)事件直接威胁核电厂安全运行。该文介绍国内核电厂高强度螺栓HE和SCC问题现状,分析了失效机理、规律和控制难点,给出对策建议。在2015—2019这5年时间里,国内核电厂共发生了 22起高强度螺栓HE和SCC事件,其中,内氢脆(internal hydrogenembrittlement,IHE)、阳极溶解型应力腐蚀(anode dissolution type of stress corrosion cracking,AD-SCC)和氢脆型应力腐蚀(hydrogen embrittlement type of stress corrosion cracking,HE-SCC)事件分别占比18%、27%和55%,与强度过高有关的事件占比55%。HE和SCC问题与时间高度关联,具有明显的慢性、偶发和随机性特征,已经成为国内核电厂高强度螺栓安全服役的主要威胁,应引起监管部门关注。长远看,建立针对高强度螺栓HE和SCC问题的行业标准、研究和使用可以有效阻断腐蚀介质到达螺栓表面的新方法、开发新型抗HE和SCC的高强度螺栓,是治理该问题的长久之策。
基金financially supported by the Natural Science Foundation of Jiangsu Province, China (No. BK20141292)the Foundation of Key Laboratory of Marine Environmental Corrosion and Bio-fouling, Institute of Oceanology, Chinese Academy of Sciences (No. MCKF201412)
文摘The hydrogen permeation behavior and stress corrosion cracking （SCC） susceptibility of precharged 7075-T6 A1 alloy were inves- tigated in this paper. Devanthan-Stachurski （D-S） cell tests were used to measure the apparent hydrogen diffusivity and hydrogen permeation current density of specimens immersed in 3.5wt% NaCl solution. Electrochemical experiment results show that the SCC susceptibility is low during anodic polarization. Both corrosion pits and hydrogen-induced cracking are evident in scanning electron microscope images after the specimens have been charging for 24 h.
基金support of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University in Chinathe National Natural Science Foundation of China (Grant No.51004084)
文摘Variation and degradation of P-110 casing steel mechanical properties, due to sulfide stress cracking （SSC） in sour environments, was investigated using tensile and impact tests. These tests were carried out on specimens, which were pretreated under the following conditions for 168 hours： temperature, 60 ℃; pressure, 10 MPa; H2S partial pressure, 1 MPa and CO2 partial pressure, 1 MPa; preload stress, 80% of the yield strength （os）; medium, simulated formation water. The reduction in tensile and impact strengths for P-110 casing specimens in corrosive environments were 28% and 54%, respectively. The surface morphology analysis indicated that surface damage and uniform plastic deformation occurred as a result of strain aging. Impact toughness of the casing decreased significantly and intergranular cracking occurred when specimens were maintained at a high stress level of 85% %.
文摘一批在生产加工后进行了淬火和低温回火的齿轮在库房存放过程中发生开裂。通过超声波探伤、金相检验、化学成分分析、硬度测试、断口形貌观察、端淬试验和补充热处理等手段,对齿轮开裂原因进行了分析。结果表明,开裂齿轮强度高导致氢脆敏感性高,在次表面产生氢致延迟裂纹是引起齿轮快速脆性开裂的直接原因。开裂齿轮淬硬性和淬透性过高,超出了BS EN 10084-2008对18CrNiMo7-6+HH钢淬透性要求,是齿轮开裂的根本原因;通过调整淬火介质,降低淬火时高温区冷速,从而降低淬回火后齿轮的强度和硬度,可有效避免开裂。
基金This project was supported by a Special Fund for the Major State Basic Research Projects (No. G19990650).
文摘The role of atomic hydrogen and hydrogen-induced martensites in hydrogen embrittlement in slow strain rate tensile tests and hydrogen-induced delayed cracking (HIC) in sustained load tests for type 304 L stainless steel was quantitatively studied. The results indicated that hydrogen-induced martensites formed when hydrogen concentration C 0 exceeded 30 ppm, and increased with an increase in C 0, i.e. M(vol%)=62–82.5 exp (?C 0/102). The relative plasticity loss caused by the martensites increased linearly with increasing amount of the martensites, i.e. l δ(M), %=0.45 M (vol %)=27.9?37.1 exp(?C0/102). The plasticity loss caused by atomic hydrogen l δ(H) increased with an increase in C 0 and reached a saturation value l δ(H)max=40% when C 0>100 ppm. l δ(H) decreased with an increase in strain rate $\dot \varepsilon $ , i.e. l δ(H), $\% = - 21.9 - 9.9\dot \varepsilon $ , and was zero when $\dot \varepsilon \geqslant \dot \varepsilon _c = 0.032/s$ . HIC under sustained load was due to atomic hydrogen, and the threshold stress intensity for HIC decreased linearly with in C 0, i.e. K IH (Mpam1/2)=91.7?10.1 In C 0 (ppm). The fracture surface of HIC was dimple if K 1 was high or/and C 0 was low, otherwise it was quasi-cleavage. The boundary line between ductile and brittle fracture surface was K 1-54+25exp(?C 0/153)=0.
