| dc.description.abstract | The 6061-T6 aluminium alloy is commonly used in automobile industry, and inert gas tungsten arc (TIG) welding and vacuum brazing(VB) welding are the most popular to be applied. Nowadays, the existing regulations only focuses on the specific fatigue assessment of melting welding. As a result, the study analyzes the differences of mechanical properties of inert gas tungsten arc (TIG) welding and vacuum brazing(VB) welding through hardness test, static fatigue test, tensile test, and metallographical observation and investigates the applicability of existing regulations as well.
According to the analysis of metallographical and hardness tests, the result is discovered that the influenced width of inert gas tungsten arc (TIG) welding is almost equal to the width of welding, whereas the base material of vacuum brazing(VB) welding exposes in hot environment for long time to annealing, precipitation hardening phase grows, which decreases the hardness; in the meanwhile, the material and welding diffusion layer are heated equally, so there is no obvious differences of hardness with heat affect zone of inert gas tungsten arc (TIG) welding. The breaking point of tensile and fatigue of gas tungsten arc (TIG) welding is different from the tests. The break of tensile test occurs in heat affect zone whereas it appears in the weak welding fulled with cracks in fatigue test. However, for vacuum brazing(VB) welding, the breaking points of tensile and fatigue both occur within welding diffusion layer. Since there is no significant differences of strength of the material, the damages appear within the positions where the weaknesses will grow easily.
Compared with each regulation, the prediction of inert gas tungsten arc (TIG) welding is in accordance with IIW within the stress range of lower cycle 104, but the trend becomes conservative for every regulation has hugh differences between higher cycle prediction and results from experiment, and this can be seen the most from the regulation prediction assessment of Euecode 9. On the other hand, the vacuum brazing(VB) welding can be not be stable predicted since it is easily influenced by properties such as the time length of holding temperature and the fixed pressure, the quality is unstable and the statistics of fatigue is distributed differently.
| en_US |