Bethlehem Steel Corp. officially dedicated the largest and most modern blast furnace in the Western Hemisphere yesterday.

Company Chairman Lewis W. Foy used the occasion as a platform to denounce critics of America's steel industry and to issue yet another warning about steel imports to the Carter administration.

In a two-hour tour of his company's huge manufacturing center here, at a symbolic ceremony opening the new $200 million blast furnace, in a news conference with reporters and in a luncheon address on technology to Baltimore area business and government leaders, Foy emphasized again and again his view of a steel industry that is not being permitted to chart its own course of growth.

"Even though this is an occasion to celebrate," Foy said, "the problem of imports must remain the industrys chief concern.

"We are hopeful, we are planning to continue spending this kind of money . . . but there is a contingency: There is not way Bethlehem or any other company can spend these sums of money to modernize and provide jobs if imports are going to continue at the level of recent months, he told the news conference.

Foy, who also heads the industry trade group, the American Iron and Steel Institute, said he is "trying very hard to work with the government" but that "pressure is building up at a very fast rate" and may force the industry to act on its own to challenge imports.

Steel imports took another jump in August despite an elaborate set of measures the administration has taken to protect domestic manufacturers from foreign competition and to prevent formal complaints about "dumping" of steel products in this country at low prices by foreign producers.

A trigger price system has been established, in effect setting minimum prices for imported steel, based on the cost of production in Japan, which Foy conceded is the lowest in the world.

The Bethlehem Steel chairman said yesterday he is "terribly distressed" about new government statistics showing that steel imports jumped to 1.89 million tons in August from $1.78 million tons in July.

"We know for a certainty that European costs are higher than those of the Japanese and ours so almost all the European steel coming in today is being dumped at less than their costs and less than they charge in their own markets," Foy asserted.

However, European imports declined in August to 662,000 tons from an abnormally high 748,000 tons the previous month. Furthermore, the absolute increase in August steel imports shows up as a decline when adjusted for seasonal variations because the imports had increased sizeably in each of the last three Augusts.

Bethlehem has threatened to file a major anti-dumping suit against European producers and Foy said yesterday that "we are living on a day to day basis" in terms of considering such actions, which would torpedo the trigger price program.

In Washington, meanwhile, President Carter described as "very successful" the initial experience with trigger prices, which did not take full effect until May. Carter told reporters at a news conference that steel shipments, employment and profits had increased and that the U.S. had a "very vigorous steel industry now."

The President said some "fine tunning" is warranted in the price measurements but added, emphatically, that "unwarranted dumping" had been stopped.

Foy's other major theme yesterday, at the 5,000 acre Sparrows Point complex east of Baltimore, was denunciation of critics he said had concluded "that we've been asleep at the switch" by falling behind in technology.

He described these critics as a "pack" led by government officials, journalists and professors, "howling that just about any and all industry problems have been due to our own reluctance of modernize."

White conceding that newer Japanese plants and some European facilities "are more advanced than most of ours," Foy noted that total U.S. steel industry capital spending exceeded $2 billion a year over the last decade while industry profits averaged $1 billion a year.

And he added, an increasing share of such spending each year is devoted to pollution control facilities. Bethlehem's own capital spending was $2.5 billion from 1973 through 1977, of which $322 million (13 percent) was for environmental controls.

Bethlehem's new blast furnace here scheduled to begin production within a few weeks, includes air and water pollution control devices that cost some $22 million.

"The installation reflects the dedication we have to the steel industry, to Sparrows Point, Baltimore and the State of Maryland," said Foy on a tour of the new plant with Acting Gov. Blair Lee III, State Comptroller Louis Goldstein, director of Bethlehem Steel and other visitors.

Bethlehem is Maryland's largest private employer, with about 19,609 workers here and in Baltimore engaged in the manufacture of a wide variety of steel products and shipbuilding.

The new furnace will produce 8,000 tons of molten iron a day, more than twice the capacity of the largest blast furnace now used here and the first of a new generation of such manufacturing facilities in the U.S. The furnace has been designated "L" and it replaces four older units.

"L" furnace is fed with ores by conveyor belt and its operation is directed by computer, which Foy said should produce higher quality iron from which steel is made in nearby buildings. About a dozen other furnaces of similar size now are being used in Europe and Japan. Some of the plant's equipment is the first of its kind made by American firms; other equipment is from Europe.

Koppers Co. Inc. was general contractor for the $200 million project. CAPTION: Picture 1, Bethlehem Steel Corp.'s new $200 million "L" blast furnace at Sparrows Point, outside Baltimore, By James M. Thresher - The Washington Post; Picture 2, Richard Zuromski, Bethlehem Steel Worker, in control center of new blast furance, the largest in America, Photos by James M. Thresher - The Washington Post; Picture 3, Bethlehem Chairman Lewis Foy with Acting Gov. Blair Lee at furance yesterday, By Bill Kyle for The Washington Post