Dezincification layer formed during corrosion or stress corrosion cracking (SCC) of brass in an ammonia solution could induce an additive stress. The effect of hydrogen on the dezincification layer induced stress and ...Dezincification layer formed during corrosion or stress corrosion cracking (SCC) of brass in an ammonia solution could induce an additive stress. The effect of hydrogen on the dezincification layer induced stress and the susceptibility to SCC were studied. The dezincification layer induced stress was measured using the deflection method and the flowing stress differential method, respectively. The latter measures the difference between the flowing stress of a specimen before unloading and the yield stress of the same specimen after unloading and forming a dezincification layer. The susceptibility to SCC was measured using slow strain rate test. Results show that both the dezincification layer induced stress and the susceptibility to SCC increase with increasing hydrogen concentration in a specimen. This implies that hydrogen enhanced dezincification layer induced stress is consistence with the hydrogen increased susceptibility to SCC of brass in the ammonia solution.展开更多
1.IntroductionSo far there are few people who studythe relationship between the criticalhydrogen concentration and the stress forhvdrogen induced cracking (CCHIC)quantitatively.Several researchers have cal-culated the...1.IntroductionSo far there are few people who studythe relationship between the criticalhydrogen concentration and the stress forhvdrogen induced cracking (CCHIC)quantitatively.Several researchers have cal-culated the CCHIC of steels under no stressby means of H permeation method,but no展开更多
The threshold stress intensity of stress corrosion cracking(SCC) for 40 CrMo steel in 3.5%NaCl solution decreased exponentially with the increase of yield strength.The threshold stress intensity of hydrogen-induced cr...The threshold stress intensity of stress corrosion cracking(SCC) for 40 CrMo steel in 3.5%NaCl solution decreased exponentially with the increase of yield strength.The threshold stress intensity of hydrogen-induced cracking during dynamical charging for 40 CrMo steel decreased linearly with the logarithm of the concentration of diffusible hydrogen.This equation was also applicable to SCC of high strength steel in aqueous solution.The critical hydrogen enrichment concentration necessary for SCC of high strength steel in water decreased exponentially with the increase of yield strength.Based on the results,the relationship between K_(ISCC) and σ_(ys) could be deduced.展开更多
The stress oriented hydrogen induced cracking (SOHIC) is a typical hydrogen embrittlement phenomenon occurring in the linepipe steels exposed to sour environment containing H 2 S gas.However,even recently,the cracking...The stress oriented hydrogen induced cracking (SOHIC) is a typical hydrogen embrittlement phenomenon occurring in the linepipe steels exposed to sour environment containing H 2 S gas.However,even recently,the cracking mechanism of SOHIC has not been clarified because of lacking in the empirical data on the actual failure mode of SOHIC cracking.The factors affecting SOHIC are discussed in terms of metallurgy of high strength linepipe steel and hydrogen electrochemistry.The cracking mechanisms of SOHIC are examined by comparing them with the empirical failure mode of SOHIC which is developed by observation of the actual fracture sites of the hydrogen induced blister cracking (HIBC) and secondary cracks.Finally,the correlation between SOHIC and HIC is discussed.展开更多
In the oil and gas industry, it has been established that for pipelines fabricated with carbon steels, their limitation is related to H<sub>2</sub>S and CO<sub>2</sub> environments, which is 7 ...In the oil and gas industry, it has been established that for pipelines fabricated with carbon steels, their limitation is related to H<sub>2</sub>S and CO<sub>2</sub> environments, which is 7 to 10 psia of partial pressure of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>. Therefore, in carbon steel cracking is shown, after 7 or 10 psia of partial pressure of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>. The experimental work was performed under static conditions in autoclaves within a pH of 3 to 3.8;partial pressures of 16 - 96 psi for H<sub>2</sub>S and 15 - 53 psi for <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>, in the temperature range of 25<span style="white-space:nowrap;">°</span>C - 150<span style="white-space:nowrap;">°</span>C. It was observed that the average yielding stress used in Sulfide Stress Cracking (SSC) tests decreases with temperature increment. Hydrogen Induced Cracking (HIC) evaluations showed that X52 steel, under conditions, was not susceptible to HIC. Results of SSC did not show indications of cracking after exposure to sour solutions, except for the specimen exposed to high H<sub>2</sub>S and <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> content (96 psi of H<sub>2</sub>S and 53 psi of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> of the partial pressure) and high temperature (150<span style="white-space:nowrap;">°</span>C). Microcracks located between the upper and lower weld beads were also observed. However, the highest average corrosion rate was 0.27 mm/year (10.6 mpy), which occurred in samples exposed to 96 psi of H<sub>2</sub>S and 53 psi of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> at 150<span style="white-space:nowrap;">°</span>C. Likewise, the highest localized corrosion (severe pitting attack) was obtained at the same environment with a corrosion rate of 4.2 mm/year (167 mpy). The oil and gas industry could use carbon steels pipelines in partial pressure higher than 10 psia.展开更多
For alloy Ti-24Al-11Nb,stress corrosion cracking(SCC) in methanol solution and hydrogen induced cracking(HIC) during dynamic charging at room temperature have been studied.Experiment has shown that the normalised thre...For alloy Ti-24Al-11Nb,stress corrosion cracking(SCC) in methanol solution and hydrogen induced cracking(HIC) during dynamic charging at room temperature have been studied.Experiment has shown that the normalised threshold stress intensities of SCC failure for various microstructures are KISCC/KC =0.53 0.69 and the threshold value for SCC arresting KISCC/ KIC=0.61-0.79.The threshold values of HIC during dynamic charging are close to that of SCC,but da/dt or fracture time of HIC is one to three orders of magnitude smaller or longer than that of SCC,respectively.The.fracture surface for HIC is also different from that for SCC.For the Ti-24Al-Nb alloy-methanol systein,a kind of inierphase SCC has been found For the microstructures resulting from furnace cooling,SCC initiated and propagated preferentially along theα2/βinterphase boundaries,displaying the microstructure on the fracture surface of SCC.However,there is no interphase SCC for the microstructure resulting from air cooling.展开更多
In this work,the crack growth behaviours of high strength low alloy(HSLA)steel E690 with three crystallographic orientations(the rolling direction,normal direction,and transverse direction)were investigated and compar...In this work,the crack growth behaviours of high strength low alloy(HSLA)steel E690 with three crystallographic orientations(the rolling direction,normal direction,and transverse direction)were investigated and compared from the view of the mechano-electrochemical ef-fect at the crack tip.The results show that the crack growth of the HSLA steel is controlled by the corrosion fracture at the crack tip.The vari-ation of crystallographic orientation in E690 steel plate has no influence on the crack tip electrochemical reaction and crack growth mechanism,but changes the crack growth rate.When the stress loading direction is parallel to the rolling direction and the fracture layer is parallel to the transverse-normal plane,the crack growth rate is the slowest with a value of 0.0185 mm·h^(-1).When the load direction and the fracture layer are parallel to the normal direction and the rolling-transverse plane,respectively,the crack growth rate is the highest with a value of 0.0309 mm·h^(-1).This phenomenon is ascribed to the different microstructural and mechanical properties in the rolling direction,normal direction,and transverse direction of E690 steel plate.展开更多
Threshold stress intensity factor of hydrogen-induced cracking (HIC), KIH, of a leadzirconate titanate ferroelectric ceramics (PZT-5) has been measured during dynamic charging with various current densities at constan...Threshold stress intensity factor of hydrogen-induced cracking (HIC), KIH, of a leadzirconate titanate ferroelectric ceramics (PZT-5) has been measured during dynamic charging with various current densities at constant load using notched tensile specimens with poling directionparallel or perpendicular to the crack plane. The results show that KIH reveals anisotropy, and thethreshold stress intensity factor for the specimen with poling direction parallel to the crack plane, K aIH, is greater than that perpendicular to the crack plane, K bIH, similar to the anisotropy of fracture toughness, KIC. The normalized threshold stress intensity factor of HIC, however, does not reveal anisotropy, and decreass linearly with logarithm of hydrogen concentration, C0, i.e. K aIH/K aIC = K bIH/K bIC = 0.4-0.15 lnC0. Therefore, the anisotropy of HIC is the same as that of the fracture tough-ness, and is due to the anisotropy of the stress-induced 90 domain switching.展开更多
Hydrogen diffusion in the wall of hydrogenation reactor for three situations, i.e. operating, normal shutdown and abnormal shutdown, was numerically simulated based on the finite element program-ABAQUS. The formula of...Hydrogen diffusion in the wall of hydrogenation reactor for three situations, i.e. operating, normal shutdown and abnormal shutdown, was numerically simulated based on the finite element program-ABAQUS. The formula of diffusion-induced stress was deduced for model of the thin walled cylinder. Distribution of diffusion-induced stress in the wall of hydrogenation reactor was studied. The results showed that the maximum stress was at the fusion surface between welding overlay and base metal and which would increase with cooling rate. The crack will initiate and propagate from fusion surface to welding overlay when the diffusion-induced stress is higher than yield stress, but it will not propagate to the base metal. Diffusion-induced stress is one of the important factors for crack initiation and propagation of welding overlay of hydrogenation reactor.展开更多
This review is about stress corrosion cracking (SCC) under anodic dissolution control. The section 1 is the methods distinguishing SCC controlled by anodic dissolution from those by hydrogen. The section 2 presents hy...This review is about stress corrosion cracking (SCC) under anodic dissolution control. The section 1 is the methods distinguishing SCC controlled by anodic dissolution from those by hydrogen. The section 2 presents hydrogen-enhanced corrosion and SCC under anodic dissolution control. The section 3 demonstrates corrosion-enhanced localized plasticity and corrosion-induced deformation localization, which are the fundaments of new mechanism of SCC. The section 4 is an overview of the proposed mechanisms of SCC under anodic dissolution control. The last section proposes a new mechanism of SCC.展开更多
文摘Dezincification layer formed during corrosion or stress corrosion cracking (SCC) of brass in an ammonia solution could induce an additive stress. The effect of hydrogen on the dezincification layer induced stress and the susceptibility to SCC were studied. The dezincification layer induced stress was measured using the deflection method and the flowing stress differential method, respectively. The latter measures the difference between the flowing stress of a specimen before unloading and the yield stress of the same specimen after unloading and forming a dezincification layer. The susceptibility to SCC was measured using slow strain rate test. Results show that both the dezincification layer induced stress and the susceptibility to SCC increase with increasing hydrogen concentration in a specimen. This implies that hydrogen enhanced dezincification layer induced stress is consistence with the hydrogen increased susceptibility to SCC of brass in the ammonia solution.
文摘1.IntroductionSo far there are few people who studythe relationship between the criticalhydrogen concentration and the stress forhvdrogen induced cracking (CCHIC)quantitatively.Several researchers have cal-culated the CCHIC of steels under no stressby means of H permeation method,but no
基金Item Sponsored by Special Funds for State Major Basis Research(G19990650)
文摘The threshold stress intensity of stress corrosion cracking(SCC) for 40 CrMo steel in 3.5%NaCl solution decreased exponentially with the increase of yield strength.The threshold stress intensity of hydrogen-induced cracking during dynamical charging for 40 CrMo steel decreased linearly with the logarithm of the concentration of diffusible hydrogen.This equation was also applicable to SCC of high strength steel in aqueous solution.The critical hydrogen enrichment concentration necessary for SCC of high strength steel in water decreased exponentially with the increase of yield strength.Based on the results,the relationship between K_(ISCC) and σ_(ys) could be deduced.
文摘The stress oriented hydrogen induced cracking (SOHIC) is a typical hydrogen embrittlement phenomenon occurring in the linepipe steels exposed to sour environment containing H 2 S gas.However,even recently,the cracking mechanism of SOHIC has not been clarified because of lacking in the empirical data on the actual failure mode of SOHIC cracking.The factors affecting SOHIC are discussed in terms of metallurgy of high strength linepipe steel and hydrogen electrochemistry.The cracking mechanisms of SOHIC are examined by comparing them with the empirical failure mode of SOHIC which is developed by observation of the actual fracture sites of the hydrogen induced blister cracking (HIBC) and secondary cracks.Finally,the correlation between SOHIC and HIC is discussed.
文摘In the oil and gas industry, it has been established that for pipelines fabricated with carbon steels, their limitation is related to H<sub>2</sub>S and CO<sub>2</sub> environments, which is 7 to 10 psia of partial pressure of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>. Therefore, in carbon steel cracking is shown, after 7 or 10 psia of partial pressure of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>. The experimental work was performed under static conditions in autoclaves within a pH of 3 to 3.8;partial pressures of 16 - 96 psi for H<sub>2</sub>S and 15 - 53 psi for <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub>, in the temperature range of 25<span style="white-space:nowrap;">°</span>C - 150<span style="white-space:nowrap;">°</span>C. It was observed that the average yielding stress used in Sulfide Stress Cracking (SSC) tests decreases with temperature increment. Hydrogen Induced Cracking (HIC) evaluations showed that X52 steel, under conditions, was not susceptible to HIC. Results of SSC did not show indications of cracking after exposure to sour solutions, except for the specimen exposed to high H<sub>2</sub>S and <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> content (96 psi of H<sub>2</sub>S and 53 psi of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> of the partial pressure) and high temperature (150<span style="white-space:nowrap;">°</span>C). Microcracks located between the upper and lower weld beads were also observed. However, the highest average corrosion rate was 0.27 mm/year (10.6 mpy), which occurred in samples exposed to 96 psi of H<sub>2</sub>S and 53 psi of <span style="white-space:normal;">CO</span><sub style="white-space:normal;">2</sub> at 150<span style="white-space:nowrap;">°</span>C. Likewise, the highest localized corrosion (severe pitting attack) was obtained at the same environment with a corrosion rate of 4.2 mm/year (167 mpy). The oil and gas industry could use carbon steels pipelines in partial pressure higher than 10 psia.
文摘For alloy Ti-24Al-11Nb,stress corrosion cracking(SCC) in methanol solution and hydrogen induced cracking(HIC) during dynamic charging at room temperature have been studied.Experiment has shown that the normalised threshold stress intensities of SCC failure for various microstructures are KISCC/KC =0.53 0.69 and the threshold value for SCC arresting KISCC/ KIC=0.61-0.79.The threshold values of HIC during dynamic charging are close to that of SCC,but da/dt or fracture time of HIC is one to three orders of magnitude smaller or longer than that of SCC,respectively.The.fracture surface for HIC is also different from that for SCC.For the Ti-24Al-Nb alloy-methanol systein,a kind of inierphase SCC has been found For the microstructures resulting from furnace cooling,SCC initiated and propagated preferentially along theα2/βinterphase boundaries,displaying the microstructure on the fracture surface of SCC.However,there is no interphase SCC for the microstructure resulting from air cooling.
基金This study was financially supported by the China Postdoctoral Science Foundation(No.2021M693706)Independent research project of State Key Laboratory of Mechanical Transmission of China(No.SKLMT-ZZKT-2021M10)the National Environmental Corrosion Platform of China(No.NECP).
文摘In this work,the crack growth behaviours of high strength low alloy(HSLA)steel E690 with three crystallographic orientations(the rolling direction,normal direction,and transverse direction)were investigated and compared from the view of the mechano-electrochemical ef-fect at the crack tip.The results show that the crack growth of the HSLA steel is controlled by the corrosion fracture at the crack tip.The vari-ation of crystallographic orientation in E690 steel plate has no influence on the crack tip electrochemical reaction and crack growth mechanism,but changes the crack growth rate.When the stress loading direction is parallel to the rolling direction and the fracture layer is parallel to the transverse-normal plane,the crack growth rate is the slowest with a value of 0.0185 mm·h^(-1).When the load direction and the fracture layer are parallel to the normal direction and the rolling-transverse plane,respectively,the crack growth rate is the highest with a value of 0.0309 mm·h^(-1).This phenomenon is ascribed to the different microstructural and mechanical properties in the rolling direction,normal direction,and transverse direction of E690 steel plate.
基金This work was supported by the Special Funds for the Major State Basic Research (G 19990650) and the National Natural Science Foundation of China (Grant No. 50131160738).
文摘Threshold stress intensity factor of hydrogen-induced cracking (HIC), KIH, of a leadzirconate titanate ferroelectric ceramics (PZT-5) has been measured during dynamic charging with various current densities at constant load using notched tensile specimens with poling directionparallel or perpendicular to the crack plane. The results show that KIH reveals anisotropy, and thethreshold stress intensity factor for the specimen with poling direction parallel to the crack plane, K aIH, is greater than that perpendicular to the crack plane, K bIH, similar to the anisotropy of fracture toughness, KIC. The normalized threshold stress intensity factor of HIC, however, does not reveal anisotropy, and decreass linearly with logarithm of hydrogen concentration, C0, i.e. K aIH/K aIC = K bIH/K bIC = 0.4-0.15 lnC0. Therefore, the anisotropy of HIC is the same as that of the fracture tough-ness, and is due to the anisotropy of the stress-induced 90 domain switching.
基金supported by Graduate Student Scientific Innovation Project of Jiangsu Province (No.CX09B 131Z)
文摘Hydrogen diffusion in the wall of hydrogenation reactor for three situations, i.e. operating, normal shutdown and abnormal shutdown, was numerically simulated based on the finite element program-ABAQUS. The formula of diffusion-induced stress was deduced for model of the thin walled cylinder. Distribution of diffusion-induced stress in the wall of hydrogenation reactor was studied. The results showed that the maximum stress was at the fusion surface between welding overlay and base metal and which would increase with cooling rate. The crack will initiate and propagate from fusion surface to welding overlay when the diffusion-induced stress is higher than yield stress, but it will not propagate to the base metal. Diffusion-induced stress is one of the important factors for crack initiation and propagation of welding overlay of hydrogenation reactor.
基金This work was supported by a special fund forIhe Major State Basic Research Projects (Grant No. G19990650) and the National Natural Science Foundation of China (Grant Nos. 19891180 and 59871010).
文摘This review is about stress corrosion cracking (SCC) under anodic dissolution control. The section 1 is the methods distinguishing SCC controlled by anodic dissolution from those by hydrogen. The section 2 presents hydrogen-enhanced corrosion and SCC under anodic dissolution control. The section 3 demonstrates corrosion-enhanced localized plasticity and corrosion-induced deformation localization, which are the fundaments of new mechanism of SCC. The section 4 is an overview of the proposed mechanisms of SCC under anodic dissolution control. The last section proposes a new mechanism of SCC.