Here's a video of my washing machine tub fire pit. This tub came from a friend who had already removed it, but it has turned out to be a perfect fire pith with some small modifications. I cut off the bottom legs and welded the base to the tub more robustly.

The coating on the tub is an enamel coating and it has held up incredibly well. Rust isn't coming through and the heat has not altered the coating at all.

As a bonus, a weber grill grate fits perfectly on the top of the tub!