淬火介质及工艺对Al-Zn-Mg-Cu合金腐蚀性能的影响

采用晶间腐蚀、剥落腐蚀、扫描电镜、透射电镜等方法,研究了不同的淬火方式对Al-6.5Zn-2.65Mg-2.2Cu-0.3Sc-0.13Zr锻造态铝合金的腐蚀性能及显微组织的影响.结果表明,空气中自然冷却淬火严重降低了T6时效态合金的抗腐蚀性能.而采用室温水淬的T6时效态合金比室温油淬的时效态合金具有更好的抗剥落腐蚀性能.当预先采用80 ℃×30 s水淬或80 ℃×30 s油淬再室温水淬时,相应T6时效态合金的抗腐蚀性能得到明显改善.预先80 ℃淬火能提高时效态合金的抗剥落腐蚀性能的主要原因是晶界析出相的大小与分布发生了明显的改变.

Effects of Quenching Agents and Process on Corrosion Resistance of Al-Zn-Mg-Cu Alloy

Effects of different quenching agents on the corrosion resistance and microstructure of as-forged Al-6.5Zn-2.65Mg-2.2Cu-0.3Sc-0.13Zr alloy were investigated by intergranular corrosion, exfoliation corrosion, SEM (scanning electron microscope) and TEM (transmission electron microscope). It is shown that corrosion resistance of the T6 treated alloy is seriously deteriorated by quenching at air. The exfoliation corrosion resistance of T6 treated alloy by quenching at ambient water is obviously superior to that of one by quenching at ambient oil. The corrosion resistance of corresponding T6 treated alloy is distinctly improved after 80℃/30s water quenching and ambient water quenching or 80℃/30s oil quenching and ambient water quenching, which is attributed to the change of size and distribution of precipitates from the grain boundary by pre-quenching at 80℃.