Research On Heat Treatment And Residual Stress Reduc-Tion Of6061Aluminum Alloy Thick Plate

Aluminum alloy thick plate is widely used. Residual stress will be produced during processing and the solid solution strengthening of thick plate, which will greatly restrict the using of material perform-ance. It’s important to explore methods to reduce residual stress of thick plate.This paper based on6061Al alloy hot-rolled plate, the double solu-tion treatment have been developed and HVSR treatment have been de-veloped by utilizing the homemade platform. The influence of solution treating times and HVSR on the residual stress, mechanical properties of aluminum alloy6061thick plate have been studied by hole drilling, hardness and room temperature tensile experiment. The microstructure and texture gradient along the thickness of the thick plate have been in-vestigated by optical microscopy(OM), scanning electron micro-scope(SEM), transmission electron microscopy(TEM) and orientation distribution function(ODF) respectively. The main conclusions are as follows:(1) The microstructure is not uniform on hot-rolled6061aluminum alloy plate along thickness direction; Organization structure contained the plate particles which with size length>1um, width0.2um, the particle is intermetallic compounds rich Si, Mg, Cu.(2)Double solution treatment has been developed, compared with conventional solution treatment, residual stress of as-quenched plate is reduced greatly, microstructure and mechanical properties tend to be uni-form along thickness direction of plate, deformation texture orientation density increase, while the typical recrystallization texture tend to random distribution. The difference of orientation density of texture between sur-face and center layer after quenching decrease.(3) Schmidt Factor of plate with components different texture un-der plane stress state was calculated by a single slip system model. The calculated results of Schmidt Factor showed that SF value of center layer of conventional solution treat sample is the largest, SF=0.212089, which is most easy to occur deformation during the quenching process. The dif-ference of SF value between surface and central layers of sample is larger than double solution treatment sample. The difference of residual stress of the as-quenched plate is ascribed to evolution of crystallographic texture, which can be explained with the weighted mean value of Schmidt Factor.(4) The residual stress of6061aluminum alloy as-quenched plate have been reduced and homogenized greatly by HVSR. Which tensile strength and yield strength improved, elongation decreased, which pre-cipitated phase more dispersion, small, well-distributed. Aging time is much shorter than artificial aging and cost reduction, which technical and economic benefit is remarkable.