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
21CrMoV5-7 Machinability (EN 10269 / 1.7709)
The machinability of 21CrMoV5-7 (Werkstoff 1.7709) in the quenched-and-tempered condition is rated 50 to 60 percent against the AISI 1212 free-machining base of 100 percent. The Cr-Mo-V Q+T microstructure with 210 to 250 HBW hardness is moderately abrasive to cutting tools; tooling and cutting parameters need to be set for medium-hard alloy steel.
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Machinability Rating
| Reference base | Rating |
|---|---|
| AISI 1212 free-machining (base = 100 percent) | 50 to 60 percent |
| AISI 1045 medium-carbon (base = 65 percent) | roughly equivalent |
| 42CrMo4 / AISI 4140 Q+T | slightly worse (45 to 55 percent of AISI 1212) |
Recommended Cutting Parameters (Turning)
| Parameter | Carbide insert | Coated carbide (TiN / TiAlN) |
|---|---|---|
| Cutting speed (Vc) | 100 to 150 m/min | 150 to 250 m/min |
| Feed (fn) | 0.2 to 0.5 mm/rev | 0.3 to 0.6 mm/rev |
| Depth of cut | 1 to 5 mm | 1 to 5 mm |
| Coolant | Flood with emulsion | Flood or MQL |
Thread Cutting
Single-point lathe thread cut for diameters above M30 / 1 1/4 inch. Multi-pass cutting recommended: 6 to 10 passes for M48, 10 to 14 passes for M64. Carbide threading inserts coated with TiAlN for the secondary hardening matrix. Rolled threading below M30 where the rolled crest gives a stronger profile.
Tool Life
Carbide insert tool life on 21CrMoV5-7 Q+T at the recommended cutting parameters: typically 30 to 60 minutes per insert edge. Tool life shorter by 30 to 50 percent compared to soft annealed bar; longer by 20 percent compared to the same chemistry over-tempered above 250 HBW.
Stress Relief After Heavy Machining
For heavily machined fastener blanks where dimensional stability matters, stress relief at 50 deg C below the final temper (typically 620 to 680 deg C) and slow furnace cool is recommended. The stress relief redistributes residual machining stresses without altering the Q+T microstructure or mechanical-property floor.
Frequently Asked Questions
Q. What is the machinability rating of 21CrMoV5-7?
50 to 60 percent against AISI 1212 free-machining (base = 100 percent). The Q+T microstructure with 210 to 250 HBW hardness is moderately abrasive to cutting tools.
Q. What cutting speed should I use for turning 21CrMoV5-7?
100 to 150 m/min with uncoated carbide insert; 150 to 250 m/min with TiN / TiAlN coated carbide. Flood emulsion coolant; feed 0.2 to 0.5 mm/rev; depth of cut 1 to 5 mm.
Q. Is thread cutting easier in annealed or Q+T condition?
Annealed condition is easier but produces a softer thread that needs subsequent Q+T (with risk of thread distortion). Q+T-then-cut is the standard practice for 21CrMoV5-7 fasteners above M30, accepting the reduced tool life for dimensional stability.
Q. Do you supply pre-machined fastener blanks?
Yes. Pre-machined bolt blanks, stud blanks and threaded-rod blanks ship from TorqBolt to the customer drawing in Q+T condition. Cuts the customer machining burden when the customer is set up only for finish threading and not roughing.
Related Properties Pages
Drill into 21CrMoV5-7 properties: Chemical Composition · Mechanical Properties · Heat Treatment · Elevated-Temperature Properties · Hardness · Creep-Rupture · Welding Procedure. Standards: EN 10269 · vs ASTM A193 B16. Back to the 21CrMoV5-7 Alloy Hub.
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