21CrMoV5-7 Frequently Asked Questions

Q. What is the correct Werkstoff number for 21CrMoV5-7?
Werkstoff 1.7709. Older or fabricated references that quote 1.7783 are wrong; 1.7783 is X22CrMoV12-1, a 12 percent chromium martensitic stainless steel for steam-turbine blades, an entirely different alloy class.

Q. Is 21CrMoV5-7 the same as 21CrMoV5-11?
No. 5-11 (Werkstoff 1.8070) has a higher Mo range (0.90 to 1.10 percent vs 0.55 to 0.80 percent for 5-7) and is the heavier-section variant. For OD up to 200 mm, 5-7 is the workhorse; above 200 mm fully-hardened, 5-11 is the preferred grade. See vs 21CrMoV5-11.

Q. What is the AFNOR or French designation for 21CrMoV5-7?
20CDV5.7 per NF A35-559. The Polish PN equivalent is 21HMF per PN-89/H-84030. See vs 20CDV5.7 and vs 21HMF.

Q. What chemistry windows govern 21CrMoV5-7?
C 0.17 to 0.25, Si max 0.40, Mn 0.40 to 0.80, P max 0.030, S max 0.030, Cr 1.20 to 1.50, Mo 0.55 to 0.80, V 0.20 to 0.35, Ni max 0.60, Al max 0.030. Full element-by-element roles on the chemistry page.

Q. What are the room-temperature mechanical-property floors?
Tensile 700 to 850 MPa, 0.2 percent proof stress at least 550 MPa, elongation A5 at least 16 percent, Charpy V impact at least 63 J at 20 deg C. Full elevated-temperature data on the mechanicals page.

Q. What Q+T cycle do you run for 21CrMoV5-7?
Austenitise 880 to 940 deg C (1 hour per 25 mm section), oil quench, temper 680 to 740 deg C (minimum 2 hours), air cool. Detail on the heat treatment page.

Q. What welding consumable matches 21CrMoV5-7?
Matched-composition Cr-Mo-V low-hydrogen filler with preheat 200 to 300 deg C and PWHT 690 to 720 deg C. Full procedure on the welding page.

Q. What is the maximum service temperature for 21CrMoV5-7?
550 deg C continuous to EN 10269. Above 550 deg C the design steps up to Durehete 1055 (Alloy T41 / 1.7729). Below 450 deg C ASTM A193 B7 is the cheaper correct choice.

Q. Is 21CrMoV5-7 an exact substitute for ASTM A193 B16?
Close but not exact. Both are Cr-Mo-V Q+T bolting steels with overlapping chemistry and similar envelope. See vs ASTM A193 B16.

Q. What is VdTUV Wb 350 and is 21CrMoV5-7 approved under it?
VdTUV Werkstoffblatt 350 is the German pressure-vessel approval scope for bolting steels. 21CrMoV5-7 is approved. Detail on the VdTUV Wb 350 page.

Q. What size range do you supply 21CrMoV5-7 in?
Round bar OD 16 to 300 mm; stud bolts M12 to M120 (lengths 50 to 800 mm); hex bolts and heavy hex bolts to M64 / 4 inch. Forgings up to 800 kg piece weight on call-out.

Q. What inspection documentation do you supply?
EN 10204 type 3.1 by default; type 3.2 with Lloyd's, DNV, BV, SGS or TUV witness on call-out and standard for turbine and pressure-vessel work.

Q. Where can I download the 21CrMoV5-7 datasheet?
On the 21CrMoV5-7 datasheet page along with the EN 10269 specification reference.