I’m so glad you asked!  (I’m supposed to be working right now, but I won’t tell if you don’t!) Women did indeed work the forges!  Keep in mind I’m focusing on Western history as that’s what I know.  I couldn’t tell you what was happening in other part of the worlds because I don’t know enough and I don’t want to be That Kind of researcher.

Here’s part of the
Holkham Bible Picture Book, an illuminated manuscript, showing a lady with a wimple going at some nails, one of the stables of the female blacksmith:

Here’s two more women working while their bearded friend works a very exciting looking bellows.

There were rules to this sort of craft, in the highly regulated world of London guilds, a woman was discouraged from becoming a master blacksmith unless she was married.  In fact, for most of Europe Master Craftswomen were expected to be married and only to take on female apprentices.  Read more about it below:

A lot of the sources for these sorts of things are old manuscripts and paper documents of censuses of craftspeople, account books, travel records and letters, and guild records.  There’s little to no record of women who received informal family training in the country or what their life was like, and so I can’t suppose after them.

Instead I can point you toward some sources where the author has waded through the archive for you.  Vicki Leon wrote about Fya upper Bach was a German blacksmith living in a time where widows of blacksmiths could legally get automatic entry into their late husband’s guild if they so desired.  As a result Germany was full of just about every kind of smith from iron to copper to silver.  Lady blacksmiths used their femininity as a selling point for their wares.  Would you like to buy a pan from a man who once looked at his dinner being cooked, or a woman who actually knows what your kitchen wares need to help you succeed?

Colonial American women had a habit of working topless for reasons that had some benefit to them greater than the inherent danger to said ladies’ ladies.  They also could take male apprentices and advertised their services in newspapers and directories before the Revolutionary War.  Often, as in the case of Betsy Hager, orphan girls were ‘bound’ as apprentices and in her case took an interest in cannons.

Blair and Ramsey list sources which mention into the fearsome reputation of the woman blacksmith as well as the rules she had to follow in a lot of Europe.

I really do need to get to work though so here are a few more sources!  I’ll let you explore those on your own.