| Analysis | Mechanical_Properties | Applications | Machineability_and_Weldability | Heat_Treating | Tolerances | Speedy Metals items |
4142 HRHT is a chromium-molybdenun alloy steel that has been hardened to 27 to 32 Rockwell C and is ready to use while still machinable and of exceedingly high strength. The chromium content provides good hardness penetration, and the molybdenum imparts uniformity of hardness and high strength. 4142 resists creep in temperatures up to 1000° F and maintains its properties even after long exposure at these relatively high working temperatures. Other desirable properties include good wear resistance, excellent toughness and good ductility in the quenched and tempered condition. 4142 HRHT is produced in rounds with its ready to use hardness with no further thermal treatments necessary.
4140 cold roll bars conforms to ASTM A-193 Grade B7, ASTM A434 Grades BC and BD
The above values are average and may be considered as representative of 4140 HRHT
4142 HRHT can be used for as wide variety of applications where greater toughness and wear resistance is needed over lower carbon grades. Typical applications include ejectors, back up and support tooling, cams, drill collars, bolts, studs, couplings, reamer bodies, axles, shafting, piston rods, rams, hydraulic machinery shafts, gears, sprockets, valves, chain links, spindles, tool bodies, tool holders, tie rods, boring bars, machinery parts and components, etc. This material roll threads, knurls, and may be plated
4142 has a machinability rating at 63% of B1112. Average cutting speed 95 ft/min. 4142 Prehard is not recommended for welding. It is best suited for welding in the annealed state, with preheating prior to welding and stress relieving after the welding operation.
4142 HRHT is pre-hardened to 27-32 Rockwell C (261/321 Brinell) and is used where no further heat treating after machining is needed due to the likelihood of warpage. 4142 HRHT can be flame hardened at wear parts to approximately 85% of a 1.00 carbon steel.
Rounds
| Size | Over | Under | Out of Round |
| To 5/16" incl | .005 | .005 | .008 |
| Over 5/16 to 7/16" incl | .006 | .006 | .009 |
| Over 7/16 to 5/8" incl | .007 | .007 | .010 |
| Over 5/8 to 7/8" incl | .008 | .008 | .013 |
| Over 7/8 to 1-1/8" incl | .010 | .010 | .015 |
| Over 1-1/8 to 1-1/4" incl | .011 | .011 | .016 |
| Over 1-1/4 to 1-3/8" incl | .012 | .012 | .018 |
| Over 1-3/8 to 1-1/2" incl | .014 | .014 | .021 |
| Over 1-1/2 to 2" incl | .015 | .015 | .023 |
| Over 2 to 2-1/2" incl | .031 | - | .023 |
| Over 2-1/2 to 3-1/2" incl | .047 | - | .035 |
| Over 3-1/2 to 4-1/2" incl | .063 | - | .046 |
| Over 4-1/2 to 5-1/2" incl | .078 | - | .058 |
| Over 5-1/2 to 6-1/2" incl | .125 | - | .070 |
| Over 6-1/2 to 8-1/2" incl | .156 | - | .085 |
| Over 8-1/2 to 9-1/2" incl | .188 | - | .100 |
| Over 9-1/2 to 10" incl | .250 | - | .120 |