Partial modification of an aluminium wrought alloy and casting by a gas tungsten arc heat source: Applicability of modification to an internal thread

Summary

Partial modification of an internal thread in an Al-Zn-Mg wrought alloy (T651) and Al-Si-Mg casting (F) has been investigated using a gas tungsten arc heat source and a copper alloying process. Threading was machined into the partial modification zone and the mechanical properties of the internal thread were evaluated by a hexagon-head-bolt tensile test. With the Al-Zn-Mg wrought alloy, the hardness distribution of the modified zone became uneven and grain boundary cracks were recognised in the modified zone. With the Al-Si-Mg casting, hardness at the modified zone increased with an increase in copper addition. Improvement in the tensile strength of the internal thread was confirmed by relevant process parameters.