PITTSBURGH (AP) -The Pittsburgh Steelers signed former Titan and Panther Justin Hartwig to a $3,725,000, two-year contract on Tuesday, making him the second free agent center they have added in as many offseasons.

Last year, the Steelers signed Sean Mahan away from Tampa Bay by giving him a $17 million, five-year contract that included a $4 million signing bonus. They plan to use Mahan as a backup at several positions, including guard and center.

The Steelers were third in the NFL in rushing last season, but Ben Roethlisberger was sacked 47 times, the second most in club history.

By adding the 6-foot-4, 312-pound Hartwig, the Steelers could have different starters at three offensive line positions. Chris Kemoeatu is expected to start at left guard for longtime All-Pro guard Alan Faneca, who signed with the Jets. Max Starks will get the chance to win back his job at right tackle from 2007 starter Willie Colon.

Hartwig's contract includes a $975,000 signing bonus and is the second he signed as a free agent in three years.

The 29-year-old Hartwig was the Tennessee's center for most of four seasons, starting 47 games, before signing a $17 million, five-year deal with Carolina in 2006. He missed all but one game that season with a groin injury but played 15 games last season until being cut two weeks ago, along with left guard Mike Wahle, during a Panthers offensive line shakeup.

The Steelers have been up against the salary cap most of the offseason, but cleared some room last week by waiving wide receiver Cedrick Wilson, who was due $2 million this season.