Stress corrosion cracking of 7020 aluminium alloy jointed by different welding methods

The results of stress corrosion cracking (SCC) of aluminum alloy AW 7020 [AlZn5Mg1] welded by friction stir welding FSW and MIG were presented. Friction Stir Welding (FSW) - a new technology can be successfully used for butt welding of different types of aluminum alloy sheets. In the article the parameters for friction stir welding ofsheets made of AlZn5Mg1 [7020] alloy was presented as well as parameters for MIG. Metallographic analysis of bonds showed a proper structural construction of both, the FSW and MIG welded 7020 aluminum alloys. Stress corrosion cracking was examined via the slow-strain-rate-testing (SSRT) according to EN ISO 7539-7. The following parameters were measured: time-to-failure - T [h], obtained max. load - F [N]; strain energy (the diagram surface under the stress-elongation curve) - E [MJ/m3]; relative elongation of the specimen — a10 [%]; max. tensile stress — R [MPa] and contraction — Z [%]. The tests were carried out on cylindrical notch-free specimens in the air and 3.5% water solution NaCl. Good resistance to stress corrosion was found of friction stir welded 7020 aluminum alloys. The tested samples cracked during SSRT test in the native material in case of FSW and in the joint in case of MIG. Original value are received results of the stress corrosion resistance of new method friction stir welded AlZn5Mg1 alloy compared with traditional MIG method.