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 Welding Procedure (EN 10269 / 1.7709)
Welding of 21CrMoV5-7 (Werkstoff 1.7709) requires matched-composition Cr-Mo-V low-hydrogen filler, controlled preheat and interpass temperature, and mandatory post-weld heat treatment (PWHT) to re-temper the heat-affected zone and restore creep performance. The procedure is qualified to EN ISO 15614-1 or ASME Section IX with hardness traverse and impact testing on the qualification coupon.
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Filler Metal
| Process | Filler standard | Designation example |
|---|---|---|
| SMAW (stick) | AWS A5.5 / EN ISO 3580-A | E9018-B3L |
| GTAW (TIG) | AWS A5.28 / EN ISO 21952-A | ER90S-B3L |
| SAW (submerged arc) | AWS A5.23 / EN ISO 24598-A | EB3 wire + appropriate flux |
| FCAW (flux core) | AWS A5.29 / EN ISO 17634-A | E91T1-B3 |
Preheat and Interpass
Preheat 200 to 300 deg C minimum, maintained throughout welding. Interpass temperature 250 to 350 deg C maximum to avoid temper softening. Diffusible hydrogen capped at 5 ml per 100 g deposited (EN ISO 3690 / AWS A4.3) using low-hydrogen consumables stored per the manufacturer humidity-control requirement.
Post-Weld Heat Treatment
PWHT at 690 to 720 deg C with hold time 1 hour per 25 mm joint thickness, minimum 2 hours. Slow furnace cool to 300 deg C, then air cool. The PWHT re-tempers the HAZ and restores the secondary-hardening V4C3 microstructure throughout the weld region.
Inspection
| Method | Acceptance | When applied |
|---|---|---|
| Visual (VT) | ISO 5817 quality level B | All welds |
| Magnetic particle (MT) | ISO 17638 / ASTM E709 | Cap and root pass |
| Liquid penetrant (PT) | ISO 3452-1 / ASTM E165 | Cap and root pass |
| Ultrasonic (UT) | ISO 17640 / ASTM E164 | Butt joints above 25 mm thickness |
| Hardness traverse | 320 HBW max | After PWHT, weld + HAZ + parent |
Procedure Qualification
Welding procedure qualified to EN ISO 15614-1 (European) or ASME Section IX (US). Qualification coupon tested for tensile, bend, Charpy V impact on weld and HAZ, hardness traverse, and microstructure check. PQR plus WPS held by the project welding engineer.
Frequently Asked Questions
Q. What filler metal matches 21CrMoV5-7?
Matched-composition Cr-Mo-V low-hydrogen filler: AWS A5.5 E9018-B3L (SMAW), AWS A5.28 ER90S-B3L (GTAW), AWS A5.23 EB3 (SAW). The B3L designation indicates the Cr-Mo-V chemistry with low-hydrogen control.
Q. What is the PWHT recipe for 21CrMoV5-7?
PWHT at 690 to 720 deg C with hold time 1 hour per 25 mm joint thickness minimum 2 hours. Slow furnace cool to 300 deg C then air cool. The PWHT re-tempers the HAZ and restores creep performance.
Q. Is preheat mandatory?
Yes. 200 to 300 deg C preheat is mandatory for 21CrMoV5-7 to control diffusible hydrogen and avoid HAZ cracking. The preheat is maintained throughout welding (no interruption) and tempered down only after final PWHT.
Q. What is the maximum HAZ hardness after PWHT?
320 HBW (34 HRC) to EN ISO 15614 standard practice. Higher HAZ hardness indicates inadequate PWHT and risks hydrogen embrittlement or stress-corrosion cracking. Hardness traverse across weld plus HAZ plus parent confirms acceptance.
Related Properties Pages
Drill into 21CrMoV5-7 properties: Chemical Composition · Mechanical Properties · Heat Treatment · Elevated-Temperature Properties · Hardness · Creep-Rupture · Machinability. Standards: EN 10269 · vs ASTM A193 B16. Back to the 21CrMoV5-7 Alloy Hub.
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