Steel 4340H-Annealed Round Bar 3-3/4" diameter Price

About 4340H|4340 with guaranteed hardenability band per ASTM A304. The 'H' suffix means the steel was tested to a Jominy end-quench specification, so you know the hardness at specific depths from the quenched end. Same chemistry as 4340 but with tighter controls. Matters when your heat treater needs to hit a specific hardness profile in a thick section and can't afford to get a bad heat that falls outside the hardenability range. If your drawing calls out 4340H, it's because the engineer wanted assurance the part would harden predictably. Machines the same as standard 4340. The premium is small and mostly about paperwork and certification. Compare to 4340 (same steel, less guaranteed hardenability) and 4140H (same concept for the 4140 family).

About Round Bar|The default starting stock for lathe work. It gets turned, bored, and parted into shafts, pins, bushings, spacers, and just about anything round.