So I'm homebrewing a race and one of their things is that they're averse to iron (I'm basing this off of how in a lot of folklore supernatural creatures are warded off by iron) and I just want to know what would make sense for them to use.
Bronze was widely used metal before iron, and was better than early low-quality iron (but harder to make): https://en.wikipedia.org/wiki/Bronze#History Bronze is still used in ship-building today.
I am not sure you can make rifles from bronze, or steam boats, but you should be able to make cannons and maybe even larger steam engines that power mine pumps, mills, factories, etc.
If their world is like earth, and you don't mind handwaving about how they found out how to do things, obvious alternatives include aluminum and magnesium, and alloys of the two. These are some of the most common things in the earth's crust, if you can separate them out.
For some uses, silica. Silica is reasonably hard, somewhat flexible, it takes a great edge,and it shatters. That last is a problem but sometimes it could be a plus.
You can also have silica bricks. And silica/aluminum clay bricks. You can make lots of things out of ceramics but if you mold it hot you have to carefully predict how it will shrink as it cools.
Calcium gives you cement. Concrete. Great compressive strength, but weak in tension or shear.
Then there's carbon. If they can make carbon fiber and graphene then there are surely lots of uses including some we haven't found yet. I can imagine that with many layers of graphene stapled together, you might get a whip for which the graphene edges might serve as an efficient saw.
Silicon carbide. Tungsten carbide. There are lots of things for special purposes. But they'll probably use what's most plentiful unless it's hard to extract. That's silicon, aluminum, carbon, and magnesium. Plus calcium for cement etc.