Thermal fatigue test has been carried out on widely used hot work steel 4Cr5MoSiV1 and a low alloyed steel 3Cr3MoV in temperature range of 200 to 700 ℃. Tempering resistance, as well as high temperature hardness/ str...Thermal fatigue test has been carried out on widely used hot work steel 4Cr5MoSiV1 and a low alloyed steel 3Cr3MoV in temperature range of 200 to 700 ℃. Tempering resistance, as well as high temperature hardness/ strength of steel specimens, works as a dominating material parameter on thermal fatigue resistance. During the heating period, high hardness can depress the inelastic deformation. This deformation is the origination of tensile stress, which acts as the driving [orce o{ heat checking during the cooling period. The cyclic strain-oxidation interac- tion can speed up the damage on surface defects, which plays an obvious role in initiation of thermal cracks. On 4CrSMoSiV1 steel specimens, borders between the matrix and inclusions such as titanium compounds, or lager car- bides such as primary carbides, are focused by strain and attacked by oxidation, and are main initiating places of cracks. While on 3Cr3MoV steel specimens, larger strain causes plastic deformation concentrating around grain boundaries. Then the following oxidation accelerates this grain boundary damage and creates cracks.展开更多
High-speed injection die casting is an efficient manufacturing technology for upgrading aluminum die-cast products.However,deficiencies(such as die damage in early period)due to larger load on the molding die compared...High-speed injection die casting is an efficient manufacturing technology for upgrading aluminum die-cast products.However,deficiencies(such as die damage in early period)due to larger load on the molding die compared with conventional technology have brought new challenges.In this study,the cause of damage generated in super high-speed injection was investigated by the combination of experimental observation of the dies and CAE simulation(e.g.die temperature analysis,flow analysis and thermal stress analysis).The potential countermeasures to solve the above problems were also proposed.展开更多
基金Sponsored by National Key Technology Research and Development Program in 11th Five-Year Plan of China(2007BAE51B04)funded by the Chinese Scholarship Committee(CSC)under document No.20093004
文摘Thermal fatigue test has been carried out on widely used hot work steel 4Cr5MoSiV1 and a low alloyed steel 3Cr3MoV in temperature range of 200 to 700 ℃. Tempering resistance, as well as high temperature hardness/ strength of steel specimens, works as a dominating material parameter on thermal fatigue resistance. During the heating period, high hardness can depress the inelastic deformation. This deformation is the origination of tensile stress, which acts as the driving [orce o{ heat checking during the cooling period. The cyclic strain-oxidation interac- tion can speed up the damage on surface defects, which plays an obvious role in initiation of thermal cracks. On 4CrSMoSiV1 steel specimens, borders between the matrix and inclusions such as titanium compounds, or lager car- bides such as primary carbides, are focused by strain and attacked by oxidation, and are main initiating places of cracks. While on 3Cr3MoV steel specimens, larger strain causes plastic deformation concentrating around grain boundaries. Then the following oxidation accelerates this grain boundary damage and creates cracks.
文摘High-speed injection die casting is an efficient manufacturing technology for upgrading aluminum die-cast products.However,deficiencies(such as die damage in early period)due to larger load on the molding die compared with conventional technology have brought new challenges.In this study,the cause of damage generated in super high-speed injection was investigated by the combination of experimental observation of the dies and CAE simulation(e.g.die temperature analysis,flow analysis and thermal stress analysis).The potential countermeasures to solve the above problems were also proposed.
