Dashes serve progressively to link nouns that serve an adjectival function, ie:
titanium
titanium alloy
titanium-alloy weld
titanium alloy-welded joints
Note in the final example that the dash disappears from between the first two words. That is because a dash helps us to associate ideas, as opposed solely to words, and hence to distinguish between them. In both the third and fourth cases the dash serves, albeit in different ways, to ensure that the reader groups ‘titanium’ and ‘alloy’ by distinguishing them from the larger list, either through inclusion, or as a form of parenthesis.
Of course, you can always avoid using a dash by turning a construction around, ie:
for: titanium alloy-welded joints
use: joints welded with titanium alloy
It’s longer, but easier on the reader’s eye.