"North American content required to qualify for NAFTA is set at between 50-60 percent under Chapter 4. With this low bar, many PRC goods and services can be regarded as Canadian products"
It's not just steel, it's basically any product due to NAFTA.
http://thehill.com/blogs/pundits-blog/economy-budget/344621-...
https://www.reuters.com/article/us-trade-nafta/nafta-meeting...