If your manufacturing employer consumes steel and that steel is now more expensive it means less of those jobs, not more. You're only pulling money from other US citizens and companies so its not really a gain to the US overall. It increases the cost of US manufactured goods that have to buy tariff laden supplies. This ends up hurting US manufacturing exports over all. All of this assumes we actually do pay for US steel but the reality is we'll just go to the next cheapest supplier which may or may not be local.
That steel is only cheap short term. Once China has a monopoly they can charge whatever they want. The only reason Chinese steel is cheaper is because it's lower quality and their government subsidizes it with long term strategic intent
There's some merit to this argument. If your goal is to hurt China's competitiveness in spite of what it costs US buyers than its a legitimate strategy.
However, this policy is being sold as a way to help US manufacturers and that's not quite the same thing. The benefits could easily go to other imports with weaker tariffs. This coupled with the problem of hurting down stream US manufacturers means that the only benefit is hedging against a Chinese monopoly and not the direct benefits that are usually talked about.
