The first big labor negotiations in a year of intensive collective bargaining begin this week in Pittsburgh with more whimper than bang, as the nation's beleaguered steelworkers and steelmakers grope for a compromise that would end the threat of a strike next summer.

As the parties come together for their third try since July, union leaders are paying almost as much attention to "bargaining" with their own rank and file as to dealing with the management types across the table.

Union leaders don't want 1982's disturbing pattern repeated. The membership, taking an increasingly hard line against concessions, twice rejected proposed "giveback contracts" worked out with management by the union's leadership. This time, officials have been involving local leaders more in the process of deciding what terms are acceptable--but their bargaining position is weak.

The top steel companies are expected to hang tough on their demands for cuts in overall employment costs, which remain the highest in American industry.

"What we got here is a western standoff," said David Wilson, a United Steelworkers district director, at his office in Baltimore. "And we got a thousand wise men in Pittsburgh beating their brains out . . . . "

The talks open tomorrow, with bargainers facing a March 1 deadline. Nearly half the industry's work force is laid off, the industry is reporting losses of $3.3 billion for 1982, and some of steel's best customers are threatening to bolt to foreign competition in order to ensure a steady supply if the risk of a strike isn't soon removed.

General Motors Corp. Chairman Roger Smith has told Steelworkers President Lloyd McBride that he must place steel orders for 1984 car models in March and might buy foreign if there is no contract.

The Steel Service Center Institute, an association of major domestic steel customers, has also urged a March 1 deadline.

As the talks begin, the man in the middle, McBride, is in a hospital with heart trouble that friends say was aggravated by the stress of union problems. He was stable and improving last week after a pacemaker was installed.

The steel negotiations raise the curtain on a big bargaining year but do not set the tone. Many of the 3.6 million workers whose contracts expire in 1983 are in healthier industries, including telephone communications, aluminum manufacturing, aerospace, and East Coast and Gulf Coast longshoring.

"We ain't talking givebacks around here," said Rozanne Weissman, speaking for the Communications Workers of America. They are geared up to bargain starting May 19 with AT&T, as it prepares to begin dividing amoeba-like next year into the new entities set up by a landmark court-ordered divestiture.

Also in 1983, an unusually large number of construction contracts will expire because of a flurry of short-term contracts negotiated in 1982.

Overall, economists predict another year of modest pay increases, with an accompanying leveling off of inflation.

The anti-concession mood in the Steelworkers union stems from a mistrust of management--in contrast to their relatively sunny labor-management relations during fat times--and from a belief that accepting less will not necessarily save their jobs. The workers want something in return.

This month, local Steelworkers union officials agreed to consider contract concessions again--but only if the companies promise to return the givebacks to the workers eventually, help laid-off workers, and plow the harvest they reap from concessions back into steel plants rather than investing it elsewhere.

Steelworkers officials said last week that U.S. Steel, the lead bargainer for the industry's "Big 8," indicated it might agree to devote some of what it saves on labor costs to modernizing antiquated steel mills. It also hinted, they said, that it might agree to cut less from hourly wages than it previously demanded and more out of holidays and benefits.

The industry was expected to insist on the same total value of concessions as it did the last time--a pay cut averaging 18 percent and worth $1.3 billion to the major steelmakers for the year.

"I think we're in a different ballpark now," said Wilson, the Baltimore union official. When you get down to a bottom-line amount, the question is do we want to strike over that amount. My feeling is we don't want a strike."