I guess Donald's main beef is with China, but they account for less than 3% of US steel imports.
The hardest blow is probably to Canada, which is a major source of both steel and aluminium for the USA.
Sweden should not be that hard hit from the initial move. Of our three major steel companies, SSAB (aka Swedish Steel) has 25% of its production in the USA, and the gains they can make there as steel prices go up, should offset any other problems. Sandvik has 26 factories within the USA, and they supply 75% of what Sandvik sells in the US. Also, Sandvik mainly sells specialty steel products and are not sure those will be subject to the tariffs, as they more or less lack US produced substitutes. The third company, Ovako, has less than 5% of sales headed to the US, so they won't lose much business directly.
There could however be secondary effects from cheap Chinese and Korean steel being redirected from the US to the European market, putting downward pressure on prices, and of course from an escalating trade war including ever more goods.
An interesting direct effect of the proposed tariffs is that Electrolux was just about to invest in a new plant for making refrigerators in the US, but has cancelled the plan as they figure with the tariffs in place, the cost for production in the USA would render the products impossible to sell.
It's hard to say just how hurtful these tariffs will be for the US (and the global) economy, but it has been calculated that the steel tariffs introduced by George W Bush in his first term caused the loss of some 200,000 American jobs.
https://en.m.wikipedia.org/wiki/2002_Un ... eel_tariff