Quote from TwoflowerSince trying to get a HC barb to 60 and failing 3 times so far, I discovered seismic slam aswell and love it. Specialy since you get it early on and it just destroys white packs.
Edit : scratch that. Gotta rethink that build some more ^^
I just got my barb to 60 in HC in 20 hours. I used Frenzy with increased movement speed and Rend with Ravage. When I got to the hard parts of Hell (certain parts of Act 3), I switched to Bloodlust rune for Rend. Other than that, I used Battle Rage, War Cry, Revenge, and Leap (Iron Impact). Nice thing about Leap is it saves you movement time and gets you into a middle of a pack, where you can rend and kill everything near you. I was able to do Normal, Nightmare, and the first parts of Hell at MP10. Gear was decent, but nothing expensive; it was all stuff I picked up while leveling my Monk and WD to 60. Only thing I spent gold on was a reduced level weapon, of which i picked up a 700 dps one at level 48 for 80k, and a reduced level shield (the armor and block amount increases are really helpful for Hell).
Also I learned a few tricks to survive hardcore along the way. I always switch to MP0 for Fields of Misery and Highlands because the charging guys can charge from offscreen and at high MP levels they can one-shot you. Also the explodey guys in Act 2 and 3 are a problem with Rend, but since you can run faster than them when they arm, I will rend and then run or leap away. Also I used a shield the entire time. Hope this helps!