Blue-collar federal workers in Alabama have threatened to strike if the Senate and the Carter Administration okay a cut in the number of longevity pay steps for the government's half million wage board workers.

The mechanics, carpenters and other blue-collar workers have a 5-step pay system now which gives beginners salaries supposedly equal to 96 per cent of non-federal pay for the same job. The top step, according to the government, is equal to 112 per cent of the going rate for the same kind of job in industry.

A Defense money bill now before the Senate would shave the blue collar pay system from five steps to three, meaning a potential pay cut - at least as far as future salary progresion of up to 12 per cent for the employees.

On Saturday, the Alabama State Council of the American Federation of Government Employees voted to strike if the Senate keeps the pay cut in its money bill, and if Carter approves it. The House killed a smiliar pay-cutting attempt. But the language was put back in the Senate bill with the blessings of the Defense Department (which employes most of the blue-collar workers) and the White House.

Strikes against the government are illegal, punishable by dismissal, a $1,000 fine and/or a year and a day in jail. But there have been walkouts (in the Postal Service and Federal aviation Administration), and government officials admit they would have a hard time enforcing the law if 500,000 people decided to break it.

The Alabama AFGE Council represents nearly 30,000 blue-collar government workers in the state. Most of them work in Defense installations or at the space agency jobs in Huntsville.