Effects of different melt-treatment methods on tensile properties at elevated temperatures and microstructure of the Al sheet for pressure cans have been investigated by OM（optical microscope）

DTA（differential thermal analysis）

SEM（scanning electron microscope）

EDAX（X-ray energy diffraction analysis） and TEM（transmission electron microscope） based on tensile testing at elevated temperatures.The results show that the existence of metallurgical defects can be responsible for the restraint of high temperature deformability and directly affect the crack propagation in the aluminum sheet as the key crack resource.Compared with the un-treatment and conventional treatment

the high-efficient melt-treatment can remarkably improve the metallurgical quality and uniformity of high temperature deformation

greatly raising the high temperature plasticity due to transgranular micro-pore gathering crack mode.The high temperature plasticity of high-efficient melt-treated aluminum sheet would be greatly deteriorated as a result of the coarsened grain size and creation of Fe（Si） phase with the deformation temperature more than 500 ℃

so the proper deformation temperature should be chosen in the range of 400

4

50 ℃.The main plastic deformation properties of the aluminum sheet from lower grade commercially pure aluminum after high-efficient melt-treatment can reach or exceed the properties of using materials

which shows the availability of lower grade aluminum raw materials.