The tribo-characteristics of metal forming at high temperatures have not yet been well understood due to the complex nature of thermal,microstructural,interaction,and process parameters.This is a review paper on the e...The tribo-characteristics of metal forming at high temperatures have not yet been well understood due to the complex nature of thermal,microstructural,interaction,and process parameters.This is a review paper on the effects of temperature,coating,and lubrication to the tribological characteristics in hot forming as well as the tribometers for different metal forming processes at elevated temperatures mainly based on the experimental work.The tribological behaviors of oxides in hot forming,such as rolling and stamping,were reviewed and presented.Some commonly used surface coatings and lubricants in hot forming were given.Many types of tribometer were selected and presented and some of them provided a great potential to characterize friction and wear at elevated temperatures.Nevertheless,more testing conditions should be further investigated by developing new tribometers.Eventually,experimental results obtained from reliable tribometers could be used in theory and model developments for different forming processes and materials at high temperatures.The review also showed the great potential in further investigations and innovation in tribology.展开更多
A finite element analysis of stress intensity factors （KI） in clamped SE（T）c specimens （dog bone profile） is presented. A J-integral approach is used to calculate the values of stress intensity factors valid for...A finite element analysis of stress intensity factors （KI） in clamped SE（T）c specimens （dog bone profile） is presented. A J-integral approach is used to calculate the values of stress intensity factors valid for 0.125≤a/W≤0.625. A detailed comparison is made with the work of other researchers on rectangular specimens. Different boundary conditions are explored to best describe the real conditions in the laboratory. A sensitivity study is also presented to explore the effects of variation in specimen position in the grips of the testing machine. Finally the numerically calculated SIF is used to determine an FCGR curve for AISI Hll tool steel on SE（T）c specimens and compared with C（T） specimen of the same material.展开更多
文摘The tribo-characteristics of metal forming at high temperatures have not yet been well understood due to the complex nature of thermal,microstructural,interaction,and process parameters.This is a review paper on the effects of temperature,coating,and lubrication to the tribological characteristics in hot forming as well as the tribometers for different metal forming processes at elevated temperatures mainly based on the experimental work.The tribological behaviors of oxides in hot forming,such as rolling and stamping,were reviewed and presented.Some commonly used surface coatings and lubricants in hot forming were given.Many types of tribometer were selected and presented and some of them provided a great potential to characterize friction and wear at elevated temperatures.Nevertheless,more testing conditions should be further investigated by developing new tribometers.Eventually,experimental results obtained from reliable tribometers could be used in theory and model developments for different forming processes and materials at high temperatures.The review also showed the great potential in further investigations and innovation in tribology.
文摘A finite element analysis of stress intensity factors （KI） in clamped SE（T）c specimens （dog bone profile） is presented. A J-integral approach is used to calculate the values of stress intensity factors valid for 0.125≤a/W≤0.625. A detailed comparison is made with the work of other researchers on rectangular specimens. Different boundary conditions are explored to best describe the real conditions in the laboratory. A sensitivity study is also presented to explore the effects of variation in specimen position in the grips of the testing machine. Finally the numerically calculated SIF is used to determine an FCGR curve for AISI Hll tool steel on SE（T）c specimens and compared with C（T） specimen of the same material.
