As a freshman legislator, Joseph V. Gartlan of Fairfax County rose to the floor of the Virginia Senate to tell his colleagues their budgetary sense was "appalling." Two years later he cut his fellow senators, Virginia gentlemen every one, deeper still by questioning the ethics of receiving per-diem expenses for days spent at home.

Gartlan, who once referred to Lt. Gov. Charles S. Robb as a "hireling," has never been accused of pulling his political punches. And after nine years in the General Assembly, the 55-year-old lawyer-legislator shows only slight signs of mellowing with age.

"The things I did broke down some barriers," Gartlan said this week between legislative duties and bites of a midday sandwich. "They weren't really such rash things."

Gartlan has not escaped Richmond's polite style of political infighting without scars of his own. Last year, for example, he was caught in the coup that led to the downfall of then-Senate majority leader Adelard Brault (D-Fairfax). The coup was orchestrated by the same Old Guard network of southside legislators whom Gartlan had helped Brault oust four years earlier.

Gartlan lost his power base just when the value of his seniority had ripened. He also was denied a seat on the important Finance Committee, an appointment he very much wanted.

"I think the things that happened last year were not done to punish me for stands taken on issues. They were directly linked to my support of Sen. Brault for Senate leadership," Gartlan said. "But I would support him again."

Gartlan does not fit any of the half-dozen stereotypes of the Virginia statesman. He was born in New York, educated at Georgetown University in Washington and, in looks and style, more resembles Ed Muskie than Robert E. Lee.

Though Gartlan is a lawyer, as are half the 140 members of the General Assembly, his law office is far from the Capital of the Confederacy on Washington's K Street. While most of Virginia's lawyer-legislators can expect to benefit directly or indirectly from their legislative posts, when Gartlan returns to Washington after each legislative session, he spends the first week figuring how much his absence cost him. The second week he explains to his Yankee clients where he has been.

"When I first got into (the Senate), I didn't have any idea the drain on my time would be as expensive as it's been," said Gartlan who admits he has enough personal wealth to guarantee he'll never have to chase fire engines for fees.

If last year was a dispiriting one for Gartlan, this session has begun well. He was assigned a seat on the powerful Senate Rules committee. And some of the bills he has championed unsuccessfully for years, including a revision of Virginia's sexual assault laws, are given good chances to pass.

"The pendulum has begun to swing back," Gartlan said.

But this year Gartlan faces another worry concerning his incumbency. The 36th Senatorial District, which he has represented since it was created after the 1970 census, will have its boundaries shifted as a result of the 1980 census. The district, which includes the eastern half of Fairfax County bordered by Alexandria on the north, the Potomac River on the east and Prince William County to the south, has been politicked smooth by Gartlan in the last decade. But in 1983, when his current four-year term expires, Gartlan will be forced to reprogram computer lists and take to unfamiliar streets.

"I wouldn't call it sobering," Gartlan said, "but I've got my work cut out for me."