Ly12铝合金化铣蚀坑形成机理

Etch-Pit Formation Mechanism of Aluminium Alloy Ly12 due to Chemical Milling

研究了淬火转移时间与８ｍｍ厚Ｌｙ１２铝合金板化铣蚀坑出现的关系．发现瞬间淬火时，合金化铣不产生蚀坑；淬火转移时间稍长时，合金化铣将产生蚀坑．合金出现蚀坑时，微观组织上沿晶界有第二相析出．第二相沿晶界析出导致晶界抗腐蚀性能降低，是引起合金化铣时产生蚀坑的基本原因．

The effect of transfer time for quenching on etch-pits found on Ly12 aluminium alloy plate due to chemical milling was studied. The result revealed that the etch-pits do come and do not come into being in chemical milling when the transfer time for quenching is transient and long,respectively. There are some 2nd phase precipitates found microscopically along grain boundaries when etch-pits take place,which will cause the boundary corrosion resistance to be reduced and be the main reason why the etch-pits form.