The United Auto Workers (UAW) will continue to battle the use of foreign-made parts and materials in US automobiles and trucks.
Its recent bargaining with Ford Motor Company and General Motors Corporation yielded the union some gains in this area. GM, for example, agreed not to close any plants in the next two years as a result of decisions to buy parts from outside suppliers, domestic or foreign. Work will be kept in GM plants, saving thousands of UAW jobs.
But the auto workers see this as only a first step toward solving an increasingly serious problem. Although plants will not be shut down, the auto company contracts will not by themselves reverse a trend toward the use of foreign parts and materials in vehicles sold in the US market.
UAW's primary concern is with parts, but the union notes that other industries are strongly affected by materials now being imported. The auto industry buys 21 percent of all the steel used in this country, 50 percent of the malleable iron, 34 percent of the zinc, 12 percent of the primary aluminum, 13 percent of the copper, and 60 percent of the synthetic rubber.
UAW-backed legislation now before Congress would require by 1985 that vehicles in the US market contain at least 25 percent parts and materials produced in this country if annual sales for a company total 100,000 to 150,000. Sales higher than that would require a greater ''US content,'' to a maximum 90 percent in those with sales of 500,000 or more in a year.
The measure, the Fair Practices in Automotive Products Act, has 119 co-sponsors in the House. Predictions about its chances of being enacted are sharply mixed on Capitol Hill. But sponsors are quick to point out that continuing high unemployment and the serious problems facing US auto and auto-supplier industries have resulted in ''considerable support'' in Congress.
Industry spokesmen generally oppose the measure. They say it would be ''impractical'' to build cars and trucks without having the flexibility to buy parts and materials in the open market.
Within the Reagan administration, international trade experts are cautioning against HR5133 for another reason. They contend that restrictive legislation could lead to trade problems with other countries - and perhaps to retaliatory trade steps.
Nevertheless, UAW is sticking to its guns. According to the union, passage of the bill could lead to jobs for 868,000 more workers by the mid-1980s and a reversal of the fortunes of industries ''now reeling under the impact of 36 straight months of crisis.''
UAW says that Big Four automakers would employ 117,000 more workers, foreign companies selling cars and trucks in the US would have to employ 146,000 more workers in North America, and parts and materials suppliers would add 605,000 more jobs if the local content law is passed.
UAW, for decades a strong supporter of free trade policies, has turned toward protectionism in recent years. In many UAW plant areas, cars carry bumper stickers proclaiming, ''Built in America by Americans for Americans.''
But many of the vehicles cannot live up to the claim made for them. The use of imported parts has grown so much over the past decade that it is now difficult to buy a car assembled with only US-made parts.