Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Durehete Machinability — Tooling Guidance for Cr-Mo-V Bolting Bar
Durehete bar in the quenched-and-tempered condition machines as a medium-strength alloy steel with hardness in the 250-320 HBW band. The Cr-Mo-V matrix is harder on tooling than plain carbon steels but well within the capability of carbide tooling at conventional speeds.
Machinability Rating
Approximate AISI B-1112 free-machining steel rating: 40 to 50 percent (where AISI B-1112 = 100 percent). Comparable to AISI 4140 quenched-and-tempered. The vanadium content increases tooling wear versus plain Cr-Mo grades; carbide tooling required for production rates.
Turning Parameters
| Operation | Tooling | Cutting speed (m/min) | Feed (mm/rev) | Depth (mm) |
|---|---|---|---|---|
| Roughing | Carbide P25 / P30 | 120 to 150 | 0.30 to 0.50 | 3 to 6 |
| Finishing | Carbide P10 / P15 | 150 to 200 | 0.10 to 0.20 | 0.5 to 1.5 |
Thread Cutting
Thread cutting on Durehete bar uses HSS or coated-carbide threading inserts. Cutting speeds 60-90 m/min for standard hex-bolt threads; coolant flood is mandatory to prevent work-hardening at the thread root. Thread rolling is preferred for high-volume production where dimensional stability allows it (Durehete 950 + 900 only; Durehete 1055 hardness can exceed thread-rolling die life).
Hex-Head Milling
Hex-head milling uses end-mills or hex-bolt forming tools at 80-120 m/min cutting speed. Coolant flood is recommended to control thermal expansion of the workpiece during the operation.
Drilling
Carbide-tipped or solid-carbide drills at 30-60 m/min cutting speed. Coolant flood through the drill is preferred for hole depths above 3x diameter to clear chips.
Frequently Asked Questions
Is Durehete 1055 harder to machine than Durehete 950?
Marginally. The Ti+B microalloying in 1055 raises tooling wear by 10-15 percent versus 950. Carbide tooling and coolant flood handle the difference; HSS tooling is workable on 950 but not recommended on 1055.
Can Durehete bar be thread-rolled?
Durehete 950 and 900 thread-roll within standard die life. Durehete 1055 is at the upper limit of thread-rolling capability; cut threads are preferred for production volumes above ~5,000 pieces.
What coolant is recommended?
Water-soluble coolant at 5-8 percent concentration. Straight oil coolants work but produce more smoke at the speeds required. Coolant flood is mandatory; mist coolant is insufficient for production rates.
Does the Q+T condition need to be re-established after machining?
Not for standard machining. Heavy plastic deformation (cold heading, severe forming) may benefit from a stress-relief at 600 degrees Celsius.
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