The specimens of 304 austenite stainless steel with the hydrogen attackbubbles or cracks were heat treated at 600 deg C for 6h. The SEM and TEM observations on thespecimens before and after the heat treatment showed t...The specimens of 304 austenite stainless steel with the hydrogen attackbubbles or cracks were heat treated at 600 deg C for 6h. The SEM and TEM observations on thespecimens before and after the heat treatment showed that the bubbles or cracks could be healedcompletely by heat treatment. The healing of hydrogen attack bubbles or cracks is closely related toheat diffusion of Fe and C atoms in austenite. The driving force of crack healing results from theplastic deforming energy E_s induced by the growth of hydrogen attack bubbles or cracks. Thecritical condition of healing of bubbles or cracks is E_s >= 2 gamma/r (where gamma is the surfacetension, r is the radius of bubbles or half length of crack). During healing of the hydrogen attackbubbles or cracks, the recovery, polygonization and recrystallization of the sub-grain also occured.展开更多
This paper integrates the characteristic of structure design and manufacture and maintenance for Chinese flat steel band wound pressure vessel(UCWPV) with the problems existing in current in service high temperature a...This paper integrates the characteristic of structure design and manufacture and maintenance for Chinese flat steel band wound pressure vessel(UCWPV) with the problems existing in current in service high temperature and pressure vessel exposed to hydrogen. In view of economy and safety it is suggested that it be practicable for UCWPV to act as reactors for platreating, hydrogenating, and catforming. UCWPV has not only potential advantages, but also removes shortages present in in-service reactors for hydrogen.展开更多
Thispaperintroduces materialandstructureofthe hydrogenation reactors, and analysesthe problems presentin use of hydrogenation reactors. Main factors which can lead to stoppingworkof reactors, are hydrogen attack, hyd...Thispaperintroduces materialandstructureofthe hydrogenation reactors, and analysesthe problems presentin use of hydrogenation reactors. Main factors which can lead to stoppingworkof reactors, are hydrogen attack, hydrogen embrittlement, temper embrittlement andstripsof overlap weldinglayer,andsomeproposalsare putforward forsafeoperation ofre actors. Finallyitissuggested thatitbe notenough only by advancing the reactor material,and adoptingthe new design and structureof reactorisimperative.展开更多
In order to investigate the effect of hydrogen attack degree on acoustic emission(AE) behavior of low carbon steel during tensiling, specimens made of Low carbon steel was exposed to hydrogen gas of 18 MPa at 450 and ...In order to investigate the effect of hydrogen attack degree on acoustic emission(AE) behavior of low carbon steel during tensiling, specimens made of Low carbon steel was exposed to hydrogen gas of 18 MPa at 450 and 500℃ for 240, 480 and 720 h respectively. Experimental results show that with increase of the hydrogen attack degree, the totally AE activity decreases during tensiling. In addition, the count of AE signals with high amplitude for the specimens with hydrogen attack keeps a constant which is less than that without hydrogen attack. It is concluded that AE signals originate in the specimens with hydrogen attack from intergranular fracture induced by methane blisterings or/and microcracks on grain boundaries.展开更多
基金Thanks are due to the National Natural Science Foundation of China(Grant No.59971011) National Key Basic Research and Development Programme of China(No.G19990650) for financial support.
文摘The specimens of 304 austenite stainless steel with the hydrogen attackbubbles or cracks were heat treated at 600 deg C for 6h. The SEM and TEM observations on thespecimens before and after the heat treatment showed that the bubbles or cracks could be healedcompletely by heat treatment. The healing of hydrogen attack bubbles or cracks is closely related toheat diffusion of Fe and C atoms in austenite. The driving force of crack healing results from theplastic deforming energy E_s induced by the growth of hydrogen attack bubbles or cracks. Thecritical condition of healing of bubbles or cracks is E_s >= 2 gamma/r (where gamma is the surfacetension, r is the radius of bubbles or half length of crack). During healing of the hydrogen attackbubbles or cracks, the recovery, polygonization and recrystallization of the sub-grain also occured.
文摘This paper integrates the characteristic of structure design and manufacture and maintenance for Chinese flat steel band wound pressure vessel(UCWPV) with the problems existing in current in service high temperature and pressure vessel exposed to hydrogen. In view of economy and safety it is suggested that it be practicable for UCWPV to act as reactors for platreating, hydrogenating, and catforming. UCWPV has not only potential advantages, but also removes shortages present in in-service reactors for hydrogen.
文摘Thispaperintroduces materialandstructureofthe hydrogenation reactors, and analysesthe problems presentin use of hydrogenation reactors. Main factors which can lead to stoppingworkof reactors, are hydrogen attack, hydrogen embrittlement, temper embrittlement andstripsof overlap weldinglayer,andsomeproposalsare putforward forsafeoperation ofre actors. Finallyitissuggested thatitbe notenough only by advancing the reactor material,and adoptingthe new design and structureof reactorisimperative.
基金This work was financially supported by the National Science Foundation of China(No.59971011) and the "973" Item of China(No.1999
文摘In order to investigate the effect of hydrogen attack degree on acoustic emission(AE) behavior of low carbon steel during tensiling, specimens made of Low carbon steel was exposed to hydrogen gas of 18 MPa at 450 and 500℃ for 240, 480 and 720 h respectively. Experimental results show that with increase of the hydrogen attack degree, the totally AE activity decreases during tensiling. In addition, the count of AE signals with high amplitude for the specimens with hydrogen attack keeps a constant which is less than that without hydrogen attack. It is concluded that AE signals originate in the specimens with hydrogen attack from intergranular fracture induced by methane blisterings or/and microcracks on grain boundaries.
