On his 24th birthday, young Andy Bean went public. Before a gallery of 18,000 and a television audience of millions, he beat the challengers, one after another, in the closing holes of the Doral-Eastern Open and took home the $40,000 first prize for his first pro tournament victory.

At the finish, the 6-foot-4, 206-pounder flashed a freckle-faced grin."Thank you, everybody," he said. He could have thanked his unflappable golf game. It refused to buckle although he was caught by David Graham on the 14th hole. He also came under the threat of old pro Tom Weiskopf who threw a 33 at him on the first nine.

The $40,000 was four times more than Bean had won in his two-season pro career. He led the tournament from the start, teed off his afternoon with a two-stroke lead and shot even par 72, finishing at 277, 11 under par and a stroke ahead of Graham. Another stroke back was Weiskopf.

A clear invitation for Bean to fold was offered by Graham, a transplanted Australian. He tied for the lead with a birdie on 14, wiping out what had been a five-stroke deficit. But the long-hitting Florida graduate responded by canning a 25-foot putt on 15, and reclaimed the lead.

Graham bogeyed 15 and 18 and Bean took a two-stroke lead to the 18th tee, despite his bogey 5 to 16. His only bad drive of the day caught a tree.

From the 18th tee, Bean made good his promise of the early morning, when he said, "If I ever am two strokes on top by the 18th, I'm gonna take an iron off the tee.I know that lake on 18, because I fished it, and it's deep, and it's close."

He attacked that 437-yard 18th with a three-iron and played it supersafe with a five-iron that left him 95 yards from the green.

Then came a wedge.

"I hit that wedge hard but it came up soft, and backed off the green," Bear said. He had to get down in two from 30 feet for the five that would clinch it.

Bean managed that with a putt that left him only six inches from the hole. "Best putt I ever sank," said the son of Tommy Bean, owner of a semiprivate golf course in Lakeland, who taught his big boy, Andy, most all the golf he knows, "and even let me a skip summer work so I could improve my game." Teen-ager Bean got a golf scholarship to Florida. Before today, his best pro performance was a 19th-place finish in the Doral last year.

Until today's 16th hole, when he got the birdie that turned back the challenge of Graham and reown him the lead, Bean birdied only the first hole. "I played aggressive golf, but until they came at me on the last nine I wasn't thinking of much more than getting my pars," he said.

On the 18the tee, he heard by the golfer's grapevine that Graham had bogeyed the last hole, and it was then that he decided on the iron strategy. "If David had parred 18, believe me, I'd have gone to a driver to make sure I had a shot at a winning par but with a two-stroke lead I played sensible golf.

Weiskopf was the hot golfer of the first nine with the 33 that drew him to within two strokes of Bean and he was still solidly in it until he, also bogeyed 18, and had to be content with third money.

In the postfinish interviews, Bean was asked if he had been thinking about getting an invitation to the Masters. "Yes, all morning I've been thinking about that invitation to the Master's," he said.

He's the newest young lion loose on the tournament tour. If he only made one birdie putt, he didn't miss any pars with his putter. And nobody outdrives him when he sets his mind to move the ball a big distance.

Bruce Lietzke, who missed the tour for three weeks because of the illness and death of his father, finished with two subpar rounds, 68 and 69, for 283 and was in a group with Jack Nicklaus tied for 11th.