Martin could compete for time at center or guard on a veteran offensive line challenged with protecting one of the NFL's best young quarterbacks in Colin Kaepernick.
The 6-foot-3, 321-pound Martin is credited for using his long arms to keep opposing defenders at bay. The Niners lost starting center Jonathan Goodwin, who had yet to sign with a new team.
In a busy day already for general manager Trent Baalke on Friday, San Francisco chose Ohio State running back Carlos Hyde earlier in the second round after pulling off a trade with Buffalo to get wideout Stevie Johnson to fill a key need in the receiving corps.
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