| Title |
Stress Corrosion Behaviour of Al - Zn - Mg Weldments - Effects of Heat Input Rate and Postweld Heat Treatment |
| Authors |
김용석(Yong Seog Kim); 변수일(Su Il Pyun) |
| Abstract |
The stress corrosion cracking (SCC) of Al-Zn-Mg welds in an aqueous solution of 3.5 wt.% NaCI (PH = 1) at 20±2℃ was studied with specimens under constant load, relative to heat input rate of the welding process and postweld heat treatment. Dendrite arm spacing determined by heat input rate was a major factor in the reduction of yield strength of welds. The failure time of welds was dependent on both heat input rate and postweld heat treatment: Electrochemical corrosion due to galvanic effect was influenced by the heat input rate. Heat input rate dependence of failure time showed that the higher the susceptibility to galvanic corrosion of welds, the lower the susceptibility to SCC of welds in the case of weld specimens, postweld-heat-treated under the same conditions (temperature and time). Weld specimens, postweld-heat-treated at 120℃ for 24 hrs showed the highest susceptibility to SCC followed by the specimen at 80℃ for 48 hrs and then that at 150℃ for 16 hrs. The postweld heat treatment effect on SCC was explained in terms of the ageing stage-SCC relation. |