剥落腐蚀对7055铝合金板材力学性能的影响

通过室温拉伸、金相显微镜和扫描电镜研究剥落腐蚀(腐蚀时间为0～48 h)对7055铝合金板材力学性能的影响。研究结果表明:随着腐蚀时间的延长,板材的强度和伸长率在最初6 h内快速下降,6 h后慢速下降;腐蚀24 h后,板材的抗拉强度降至500 MPa以下,伸长率降至1%左右;腐蚀48 h后,板材的强度和伸长率分别下降约28%和87%;剥落腐蚀后板材表层产生了大量的沿晶腐蚀裂纹和腐蚀缺口;在拉伸时,腐蚀缺口处产生应力集中,增加了裂纹源数量,这是力学性能下降的主要原因。

Effect of exfoliation corrosion on mechanical properties of 7055 aluminum alloy sheet

The effect of exfoliation corrosion on the mechanical properties of 7055 aluminum alloy sheet was investigated by ambient tensile testing,optical microscopy and scanning electron microscopy.The results show that with the increase of the corrosion exposure time,both strength and elongation decrease rapidly within the initial 6 h and then slowly after 6 h.After corrosion exposure for 24 h,the ultimate strength is decreased to below 500 MPa and elongation is decreased to about 1%.After 48 h the strength and elongation are decreased by about 28% and 87%,respectively.Exfoliation corrosion exposure leads to a number of intergranular cracks and corrosion notches in the surface layer of the sheet.During the tensile test,stress concentration occurs at the bottom of corrosion notches,and thus the number of crack sources is increased,which is supposed to primarily be responsible for the decrease in the mechanical properties.