After a week of jokes, smiles and waves at every available television camera, Teng Hsiao-ping has joined the ranks of Nikita Khrushchev, Chou En-lai and other Communist leaders who have charmed the Americans they rubbed shoulders with.

"Americans like heroes," said a senator who watched Teng soothe his sharpest critics on Capitol Hill.

Just as deftly as he used a handkerchief rather than his usual spittoon, Teng finessed the still serious U.S.-Chinese differences over Taiwan and human rights.

After decades of less than fraternal dealings with Soviet diplomats and after having been purged twice by his Chinese Communist Party Politburo colleagues, Teng may have a keener appreciation than most people of the limits of trust and friendship.

Versions of recent unpublished speeches by Teng, some from Taiwan sources but judged authentic by Western analysts, refer bluntly to unfriendly intentions of American leaders and the need to use the United States without getting too close to it.

A media event as well orchestrated and lively as Teng's U.S. visit opens up the possibility of future public disappointments, when the Communist leader shows a sterner face back in Peking. There are numerous pitfalls ahead for the U.S.-Chinese relationship.

During his visit in Washington, however, Teng bent over backward to avoid even suggesting a serious split between Washington and Peking over Taiwan. He told senators and reporters that he could not entirely rule out the use of force against the island because to do so would give Taiwan's leaders no incentive to negotiate a peaceful end to the half-century-old Chinese civil war.

When a questioner tried to press the vice premier on the question of a possible invasion of Taiwan, Teng's interpreter cut him off, insisting the Chinese leader had already answered the question.

American officials who have been in touch with the Chinese in Peking, however, say they have been assured China will protest vigorously and publicly when Washington announces its next sale of arms to Taiwan -- as tacitly allowed under the normalization agreement.

Similar vehement Chinese statements about Japanese efforts to explore for oil in the East China Sea have brought protests in the Japanese parliament. The U.S. Congress is not likely to take a verbal attack on the United States any more kindly.

The Chinese have never recanted what they said in a Nov. 1, 1977 People's Daily editorial: "U.S. imperialism has not changed as far as its policies of aggression and hegemonism are concerned, nor has it lessened its exploitation and oppression of the people at home and abroad."

The point is simply not made very often or very prominently now; the focus is placed instead on a later statement in the editorial that "the Soviet Union [is] the more dangerous instigator of world war."

The trade agreements and business deals that should provide the bulk of news about U.S.-China relations in the coming months contain their own limits and potential problems, obscured by the euphoria surrounding Teng's trip and the agreements he signed here.

Major American-managed construction projects like the six Intercontinental hotels or the huge U.S. Steel iron ore processing plant are likely to run into delays through the failings of Chinese bureacracy and the difficulties of communication between U.S. engineers and Chinese laborers. This may dampen the enthusiasm of American businesses eyeing the China market, an enthusiasm even leading promoters of China trade here think has gone too far.

One other potential problem area involves human rights. Secretary of State Cyrus Vance described the U.S. position on the issue in talks here with Teng, but there is no sign the Chinese made any response. Teng said in Peking he did not want to discuss the subject and it is still very uncertain how long the pro-democracy wall poster campaign in Peking will continue.