PSI - Issue 76

Filip Likavčan et al. / Procedia Structural Integrity 76 (2026) 145– 150

147

melt during the casting process · During welding, insufficient penetration of the weld root or burn-through as a result of inappropriate welding parameters with varying tube and profile thicknesses. Fig. 2 shows fractures in some bicycle frame components caused by defects in the microstructure of the material due to the casting or welding technology.

Fig. 1. Strength properties of aluminum alloy AW6082 for various processing technologies.

a/

b/

c/

Fig. 2. Fractures of bicycle components due to internal defects during casting (cavities and defects in pictures a/ and b/), welding (unmelted weld) picture c/ Internal defects after casting most often manifest themselves under dynamic loads during operation and can also be the site of fatigue crack initiation under cyclic loading. Welding due to the thermal influence of the environment and remelting of the weld joint eliminates the positive effect of previous heat treatment. If the desired properties of the aluminum alloy are to correspond to the T6 condition, the material properties at the weld joint after welding should correspond to those of the material in the T4 condition. Incorrectly selected welding parameters can further reduce these properties, as documented by the comparison of the S-N curves in Fig. 3, where the experimental points "AL6061welded badly" correspond to the welded joint in Fig. 2c/.