The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy （SEM） and optical microscopy, the main crack length was observed and measured. The ...The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy （SEM） and optical microscopy, the main crack length was observed and measured. The initiation sites of the tested alloys are different in as-cast （named as K465） and solution heat treatment （named as SK465） conditions. In K465 alloy, most thermal fatigue cracks nucleate at （Nb,W,Ti）C carbides. In SK465 alloy, thermal fatigue cracks initiate in interdendritic regions, MC-type carbides and some interfaces. Thermal fatigue cracks propagate in transdendritic mode, and M6C-type carbides could retard thermal fatigue crack growth for SK465 superalloy.展开更多
The formation and growth of thermal fatigue crack in chromium wear resistant cast iron was investigated, and the effect of hot deformation on the crack was analyzed by means of optical microscope and scanning electron...The formation and growth of thermal fatigue crack in chromium wear resistant cast iron was investigated, and the effect of hot deformation on the crack was analyzed by means of optical microscope and scanning electron microscope and high frequency induction thermal fatigue tester. The results show that eutectic carbide is the main location and passage for initiation and extension of thermal fatigue cracks, hot deformation can improve the eutectic carbiders morphology and distribution, inhibit the generation and propagation of thermal fatigue cracks. In the experiment, the propagation rate of thermal fatigue crack reduces with the quantity of hot deformation increasing, which was analyzed in the point view of the activation energy of crack propagation.展开更多
Thermal fatigue failure is one of the main failure forms of 8407 steel. Aiming at improving the anti-thermal-fatigue property of 8407 steel, the method of aluminization and subsequent oxidation is employed to form a c...Thermal fatigue failure is one of the main failure forms of 8407 steel. Aiming at improving the anti-thermal-fatigue property of 8407 steel, the method of aluminization and subsequent oxidation is employed to form a complex oxide on the die surface. Thermal fatigue test was performed with the cycle heating method to compare thermal fatigue behaviors of 8407 steel samples with and without aluminization and oxidation treatment. In the test, thermal fatigue crack morphology formed on the surface was observed by scanning electron microscope （SEM） and then variations of initiating rate and propagating rate of main crack of thermal fatigue with cycles were investigated. Moreover, the thermal fatigue property was judged according to thermal fatigue main crack length and its reciprocal. Finally, the anti-thermal-fatigue mechanism of oxide film was clarified. The results show that the surface aluminization and oxidation treatment can improve both the initiating resistance and propagating resistance of thermal fatigue crack, which will improve the anti-thermal-fatigue property of 8407 steel.展开更多
文摘The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy （SEM） and optical microscopy, the main crack length was observed and measured. The initiation sites of the tested alloys are different in as-cast （named as K465） and solution heat treatment （named as SK465） conditions. In K465 alloy, most thermal fatigue cracks nucleate at （Nb,W,Ti）C carbides. In SK465 alloy, thermal fatigue cracks initiate in interdendritic regions, MC-type carbides and some interfaces. Thermal fatigue cracks propagate in transdendritic mode, and M6C-type carbides could retard thermal fatigue crack growth for SK465 superalloy.
基金ItemSponsored by Guiding Programof Science and Technology Research of Jilin Province of China (20000513)
文摘The formation and growth of thermal fatigue crack in chromium wear resistant cast iron was investigated, and the effect of hot deformation on the crack was analyzed by means of optical microscope and scanning electron microscope and high frequency induction thermal fatigue tester. The results show that eutectic carbide is the main location and passage for initiation and extension of thermal fatigue cracks, hot deformation can improve the eutectic carbiders morphology and distribution, inhibit the generation and propagation of thermal fatigue cracks. In the experiment, the propagation rate of thermal fatigue crack reduces with the quantity of hot deformation increasing, which was analyzed in the point view of the activation energy of crack propagation.
基金Item Sponsored by Beijing Company Limited of ASSAB Tooling(2008-0-1-207)
文摘Thermal fatigue failure is one of the main failure forms of 8407 steel. Aiming at improving the anti-thermal-fatigue property of 8407 steel, the method of aluminization and subsequent oxidation is employed to form a complex oxide on the die surface. Thermal fatigue test was performed with the cycle heating method to compare thermal fatigue behaviors of 8407 steel samples with and without aluminization and oxidation treatment. In the test, thermal fatigue crack morphology formed on the surface was observed by scanning electron microscope （SEM） and then variations of initiating rate and propagating rate of main crack of thermal fatigue with cycles were investigated. Moreover, the thermal fatigue property was judged according to thermal fatigue main crack length and its reciprocal. Finally, the anti-thermal-fatigue mechanism of oxide film was clarified. The results show that the surface aluminization and oxidation treatment can improve both the initiating resistance and propagating resistance of thermal fatigue crack, which will improve the anti-thermal-fatigue property of 8407 steel.
