Traders also were encouraged by news Trump might meet North Korean leader Kim Jong-un.
The move drew consternation outside the U.S.
Beijing said it was ready to retaliate if Chinese companies are hurt, but Friday's statement gave no indication of official action.
The two metals are "the bedrock of our defence-industrial base", the president said on Thursday. "We'll terminate NAFTA and do it all over again... but I think we'll make a deal", he said during a White House signing ceremony.
"Our industries have been targeted for years and years - decades, in fact - by unfair foreign trade practices", Trump said.
The Foreign Secretary, reacting to Trump's imposition of the tariffs, said yesterday: "We don't think that tariffs on United Kingdom steel are a good idea".
$15 billion of the two metals combined were exported to the USA a year ago.
While that is not a lot for the economy as a whole, it would be painful for the individual industry.
And Trump repeatedly claimed that America's trade partners were robbing the country of $800 billion on an annual basis, and that it would be worth slapping "75 percent" tariffs on some nation's imports to combat this menace.
India's miniscule export of steel to the USA means it may breathe freely, but not other major countries. Representative Peter Roskam (R-IL) also released a statement, saying, "While we must stop countries like China from dumping steel in our market, the actions taken today by the Administration could hurt companies, employees and consumers in my district". Meanwhile, U.S. Steel Corp. said it would reopen a closed mill in IL.
Cecile Shea, an global consultant, worries about the long-term impact on other industries such as Caterpiller. "We will continue to urge the administration to narrow this policy so that it is focused only on those countries and practices that violate trade law", Ryan said. Trump has also threatened to impose hefty tariffs on European vehicle exports if the EU does take retaliatory measures.
Eggert said "the loss of exports to the US, combined with an expected massive import surge in the European Union could cost tens of thousands of jobs in the European Union steel industry and related sectors".
Sasse predicted a trade war was ahead and Nebraska stands to lose big.
U.S. Senator Joni Ernst Senator Ernst of Iowa joined a parade of other Republicans calling for President Trump to reconsider.
When imported steel and aluminum cost far more here than elsewhere, many jobs manufacturing planes, cars, tractors, tools, factory machinery, robots and rebar will go to those cheaper nations. "Under current circumstances, this tariff is necessary and appropriate to address the threat that imports of steel articles pose to the national security". China accounts for only a small fraction of USA steel imports, but its massive industrial expansion has helped create a global glut of steel that has driven down prices.
"The steel industry are the crybabies of the Beltway lobby farm", said Stockman.
The tariffs will affect a wide range of products, including high-tech gadgets, food, furniture and beverages.
Mr Trump has said the United States is suffering from "unfair trade" and that the move would boost USA industry.
"Any business or any manufacturer that utilizes steel or aluminum is potentially going to be harmed by this", said Johnson.
China has accused Donald Trump of damaging the global trading system by hiking steel and aluminium tariffs, while Japan and South Korea expressed alarm at potential economic damage.
"A tariff is a tax, plain and simple", said Matthew Shay, president and CEO of the NRF.
Theresa May told Trump of her concerns over the tariff plan on the weekend and warned against starting a trade war with the EU.