Forging a right angle in a bar is great pratice. I use this technique on the right angle hooks which are great for practicing this.
The basic idea is to put a rough bend in the bar by quenching the end from the bend and using it as a lever. Then you refine the bend by knocking down the bar from the end.
To further refine the bend keep working from both sides. Work right on the corner and don’t overdo it or you’ll put a crease on the inside of the corner.