The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morpholo...The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morphology was observed by means of electron backscatter diffraction(EBSD)technology.The results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain rate.In contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain rates.The microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix zones.The grain size in the welding zone was smaller than that in the matrix zone due to lower DRX fraction.The decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.展开更多
As a good method to solve the problem of high methane on the workface and inthe goaf,drawing coal strata methane through a surface borehole is used.However,theexcavation affected the overlying rock strata greatly.When...As a good method to solve the problem of high methane on the workface and inthe goaf,drawing coal strata methane through a surface borehole is used.However,theexcavation affected the overlying rock strata greatly.When the excavation face passedthrough the surface borehole position,the surface borehole fractures fast.This problemwas seriously related to the unformed squeeze effect.Therefore,a squeezing deformationfracture model based on the rock strata squeezing effect was set up.At the same time,a3DEC simulation model is presented to confirm the theory.The result shows that the modelis reliable and has a good engineering application value.展开更多
基金Project(U1664252)supported by the National Natural Science Foundation of China
文摘The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and simulation.The grain morphology was observed by means of electron backscatter diffraction(EBSD)technology.The results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain rate.In contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain rates.The microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix zones.The grain size in the welding zone was smaller than that in the matrix zone due to lower DRX fraction.The decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.
基金Supported by the National Great Research Foundation of China(973)(2005CB221504)the National Natural Science Foundation of China(50534080)the National Key Technology R&D Program(2006BAK03B03)
文摘As a good method to solve the problem of high methane on the workface and inthe goaf,drawing coal strata methane through a surface borehole is used.However,theexcavation affected the overlying rock strata greatly.When the excavation face passedthrough the surface borehole position,the surface borehole fractures fast.This problemwas seriously related to the unformed squeeze effect.Therefore,a squeezing deformationfracture model based on the rock strata squeezing effect was set up.At the same time,a3DEC simulation model is presented to confirm the theory.The result shows that the modelis reliable and has a good engineering application value.
