应力幅对LY12CZ铝合金腐蚀疲劳应变电流响应的影响

INFLUENCES OF STRESS AMPLITUDE ON THE TRANSIENT CURRENT BEHMIOR FOR LY12CZ ALUMINUM ALLOY DURING CORROSION FATIGUE

研究了 ＬＹ１２ＣＺ铝合金在应力控制下于 ３．５％ ＮａＣｌ溶液中恒电位下，应力幅对腐蚀疲劳（ＣＦ）应变电流行为的影响以及应变电流与腐蚀疲劳损伤相对应的关系结果表明：应变电流能反映 ＣＦ不同阶段的损伤行为应变电流的波型随 ＣＦ过程所发生的变化主要表现在应变电流的波幅、波峰数及其与应力波的相位差上不同应力幅下的应变电流行为的差异主要表现在：高应力幅下，在一个循环周次内，瞬变电流在整个腐蚀疲劳过程中均出现两个波峰；而低应力幅下，腐蚀疲劳初始阶段和裂纹扩展最后阶段均只出现一个波峰长距离显微镜（ＱＲＭＳ）的动态观测表明，高应力幅下产生的表面裂纹数明显多于低应力幅下的表面裂纹数，从而使得高应力幅下的最大峰值电流密度（Ｊｍ）和应变电流波幅均比低应力幅下的要高。

Influences of stress amplitude on the transient current behavior during corrosion fatigue for LY12CZ aluminum alloy in 3.5% NaCl at constant potential under the load control condition have been studied. The results indicated that as the cycling processed the transient current amplitude the number of the current peak will change, which could provide valuable information of the damage at different stages of corrosion fatigue. At the high stress amplitude there are two current peaks in each fatigue cycle during the whole cycling. However at the low stress amplitude there is only one current peak in each fatigue cycle at the saturated stage and the high crack propagation stage although there are two peaks at the crack initiation stage. The Questar Remote Measurement System (QRMS) observations show that there are more cracks on the surface at high stress amplitude as comparison to low stress amplitude, which agrees well with the higher current density and amplitude at relatively high stress amplitude recorded during corrosion fatigue.