预拉伸厚铝板内部残余应力与晶粒取向均匀性的研究

Internal Residual Stress and Texture Homogenization in Pre- stretch Aluminum Alloy Plates

目的消减预拉伸铝板内部残余应力。方法利用短波长X射线衍射仪(SWXRD),分别对某公司国产25 mm厚2024-T351预拉伸铝板,以及美国铝业公司(ALCOA)20 mm厚7075-T651预拉伸铝板的内部残余应力、内部织构及其沿板厚的分布,进行了无损测定。结果 ALCOA的20mm厚7075预拉伸铝板内部残余应力小于25 MPa,其内部晶粒取向沿板厚均匀分布;而某公司原工艺生产的25 mm厚2024预拉伸铝板,内部残余应力高达100 MPa左右,其内部晶粒取向沿板厚分布很不均匀。结论源自于轧制的内部织构沿板厚分布的不均匀性,使得以消减残余应力为目的的预拉伸处理中的铝板塑性变形不均匀,导致某公司国产预拉伸铝板内部残余应力的消减效果差,在其后续加工中容易产生加工变形超差的问题,需要抑制强剪切织构的产生,减小织构在整个板材厚度上的不均匀分布程度。

Objective To decrease the residual stress in pre- stretch plates. Methods The internal residual stress,internal texture and its distribution along the plate thickness were measured non- destructively for the domestic produced2024- T351 aluminum alloy pre- stretch plate with a thickness of 25 mm and the ALCOA 7075- T651 aluminum alloy pre- stretch plate with a thickness of 20 mm by means of the self- developed short- wavelength X- ray diffractometer（ SWXRD）. Results The results showed that the internal residual stress was less than 25 MPa and the internal texture was homogeneous along the plate thickness for the ALCOA 7075- T651 aluminum alloy plate,and the internal residual stress was much higher（ reaching about 100 MPa） and the internal texture was quite inhomogeneous along the plate thickness for the domestic 2024- T351 aluminum alloy plate. Conclusion The inhomogeneous distribution of the internal texture along the plate thickness led to the inhomogeneous plastic deformation of the aluminum plate in the pre- stretch treatment aimed to reduce the residue stress,and finally caused the poor reduction of internal residue stress by the domestic aluminum alloy pre- stretch plates. Therefore,suitable rolling process should be adopted to obtain homogeneous texture,and the strong shear texture should be restrained to increase the texture homogenization.