The first part of the lesson is to make sure the steel is high-carbon steel, since most other steels aren’t able to be heat treated. It will also have a specific method for its quenching ...

US President Donald Trump’s threatened steel tariffs that don’t kick in for two weeks are impacting US buyers who already are seeing American-made metal cost more than imports.

The influx comes amid relatively anemic US steel demand as high borrowing costs make it expensive for buyers to move ahead with projects in everything from construction to appliance manufacturing.

He then hammers the tough, low-carbon steel, which he has shaped so it will make a snug fit into the channel and forges the two metals together. Both types of tamahagane are now exactly where they ...