Rockwell International Corp. has heated the debate involving backers of the B1 and Stealth bombers in Congress, but not at the Defense Department, by offering to build 48 more of its B1s for what the company considers a bargain price, $195 million apiece.

Rockwell officials, saying yesterday that they made the offer last month but have not received a response from the department, said they are not trying to shoot down the Stealth bomber being developed by Northrop Corp. in California.

Instead, a Rockwell executive said, the company made the $195 million offer in hopes of stimulating the Pentagon to negotiate for more than the 100 B1s already ordered. Otherwise, they said, Rockwell must fire about 20,000 of the 23,000 employes working on the B1 by the time production of the 100 bombers stops in 1988.

"We have said we will buy 100 bombers, and that's it," Pentagon spokesman Fred S. Hoffman said when asked for reaction to the Rockwell offer. "There has been no change in the building on that" since it was received, he added.

The Pentagon has revealed to only a selected few officials and defense executives how much the Stealth bomber will cost despite congressional demands to make the information public. Unofficial estimates are as high as $80 billion for 132 bombers, or $600 million apiece, by the time Stealths are produced in the 1990s.

Donald A. Hicks, a former Northrop senior vice president who is the Pentagon's research director, has dismissed such estimates, telling Congress that Stealth will cost no more than 3 percent more than the B1. He did not disclose how he arrived at that estimate for a "flying wing" bomber not yet tested or produced in quantity.

Rep. Mike Synar (D-Okla.), whose congressional district is home for many Rockwell workers, said yesterday that the Rockwell offer "will move the bomber debate in Congress to the front burner" by forcing debate on the question of Stealth's cost and what the country will get for the money.

Synar has been at the forefront in Congress in pressing the Pentagon to release Stealth cost figures. In declining to do so, the Pentagon has said such information would help the Soviets by disclosing the program's scope.

Synar said Hicks used fiscal 1981 dollar figures to make his comparisons between the bombers. If the Stealth figures were determined for the years in which the bombers are expected off the production line, "the true cost of Stealth becomes $75 billion to $80 billion," Synar said.

"We should place a cap on the The Pentagon has revealed to only a selected few officials and defense executives how much the Stealth bomber will cost. total program cost and require congressional approval for any expenditures higher than that cap. We should require testing of the Stealth bomber before providing funds for production," he said.

President Reagan reversed President Jimmy Carter's decision and ordered the B1 into production in 1981. The plane's Air Force and congressional backers said it would fill the gap between old B52s and Stealth's appearance.

If Rockwell's offer impels Congress to force the Pentagon to stage a B1-Stealth competition before closing down the Rockwell production line, Northrop would be in a familiar situation.

Northrop had successfully pushed for a competition between its F20 fighter, developed but not in production, and General Dynamics' F16, then in volume production.