Steel production barely increased over the past year. Aluminum production has risen more, but it remains more than 40 percent down from where it was in 2015. The United States produced 890,000 metric tons of aluminum in 2018 — barely more than Iceland, well below Norway and less than 3 percent of the output of China.

Executives at foreign-owned metals producers, which were supposed to bear the brunt of America’s tariffs, say Mr. Trump’s levies have largely been an annoyance and, ironically, a hindrance to their operations in the United States. They say tariffs have not changed the competitive landscape in the global aluminum or steel business.

“The main effect in the markets seems to be that aluminum is becoming more expensive for the U.S. consumer” relative to people elsewhere around the world, said Kathrine Fog, the head of corporate strategy and analysis for the Norwegian aluminum giant Norsk Hydro, in an interview in the company’s Oslo headquarters.

Ms. Fog and other Hydro executives say that on their list of worries over the last year, Mr. Trump’s trade policies ranked well below cyber attack, South American courts and executive turnover. The only harm they have suffered from the tariffs, which still apply to Norway and other European allies of the United States, has come through the aluminum extrusion plants they operate in the United States, which import some of their source materials from Canada. Lifting the tariffs on Canada will ease that pain, officials say.

At the end of last year, after months under the tariffs, the United States still produced barely two-thirds the aluminum of Norway — a country with just 5 million residents — according to the United States Geological Survey. It produced one-tenth the amount of raw steel as China, and its steel output was still growing slower than China’s.

Since Mr. Trump imposed metal tariffs on trading partners last spring, aluminum prices worldwide have fallen nearly 20 percent. That is attributable in large part to China’s government-supported smelters, which poured additional supply into the global market, as well as falling demand for aluminum in Europe and other large economies. Production costs also declined worldwide.

Aluminum prices in the United States have fallen substantially less, by about 9 percent, according to data compiled by Harbor Aluminum, an industry analysis firm. The premium that American consumers pay for aluminum, compared to what others pay on the global market, has doubled since the administration began the government investigation in 2017 that ultimately authorized the metal tariffs. Today, American manufacturers that use aluminum in their products pay 22 percent more for the metal than their international competitors, including countries like Norway and Canada.