Dear Mr. Sankaran,
1. For SS 410 (martensitic stainless steel), PWHT directly affects hardness, toughness, and risk of cracking. Metallurgically SS 410 forms untempered
martensite after welding, so PWHT is mandatory in most cases. PWHT is required to temper martensite, reduce hardness, and relieve residual stresses.
2. Applicable Standards / References: ASME Section II / IX – Material & Welding Qualification. AWS D1.6 – Structural Welding Code (Stainless Steel);
Industry practice for martensitic (410/420 series) SS materials.
3. Evaluation of PWHT Temperature Options:
Option 1: 650–700°C (Selected range)- Achieves effective tempering of martensite. Reduces hardness to acceptable range (~200–250 HV). Maintains
optimum balance of strength and toughness. Minimizes risk of over-tempering, grain coarsening and loss of mechanical properties.
Conclusion: Metallurgically stable and widely accepted range for SS 410.
Option 2: ~760°C (Higher range) - Produces further softening (lower hardness), may improve ductility marginally, however it introduces risks of over-
tempering resulting in reduction in tensile strength, possible degradation of creep/structural properties. This typically used when hardness reduction is
critical (e.g., NACE/ field service requirement), when the weld is too hard (>~250–275 HV), and for thick restrained joints. Not required unless hardness
reduction is specifically mandated and service conditions demand higher ductility.
Conclusion: Not preferred for general applications.
4. Code Compliance: ASME and AWS do not mandate a fixed PWHT temperature for SS 410. They require a PQR demonstrating acceptable properties,
control of hardness, strength, and soundness. The selected range 650–700°C complies, as it produces acceptable mechanical properties during qualification.
5. Justification: The PWHT temperature range of 650–700°C is selected because, It ensures adequate tempering of martensitic structure; Achieves required
hardness reduction without compromising strength; Avoids risks associated with higher temperature exposure (~760°C); Aligns with established industry
practice and metallurgical principles. Meets procedure qualification and code acceptance criteria.
6. Conclusion: PWHT at 650–700°C (1 hr/25 mm, furnace cooling) is technically justified, code-compliant, and optimal for SS 410 weldments. PWHT at ~760°C
is not necessary and is only to be used when specifically required by design or hardness criteria.
Sridhar.
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--Dear Mr Sridhar,
good & wishes for detailed explanation for welding of dissimilar material . All the inputs & parameters are found as good and meeting the standard requirements. small suggestion on PWHT temperature as given below:as per ASME sec VIII div-1 for 410 type steel- PWHT temperature will be 760deg C, kindly check & proceed further
Regards,Sankaran.SPWelding & Metallurgy expert
Coimbatore, India.
On Tuesday, 17 March 2026 at 09:05:28 pm IST, sridhar cn <sridharcn305@gmail.com> wrote:
Giving below are the hints for WPS (both ISO / AWS) for joining SS 410 (martensite) to SS 316 (austenitic).
This should be supported by a PQR qualification.
WPS: Dissimilar Joint: SS 410 vs. SS 316
1. General Information:
Process: GTAW (Root) + SMAW / GMAW (Fill & Cap); Type: Dissimilar stainless steel welding
2. Base Materials:
SS 410 (UNS S41000) – 410 Martensite SS to SS 316 – Austenitic SS; ASME sec. IX P no 6 (410) to Pno 8 (316)
3. Joint Details:
Joint Type: Butt joint; Thickness Range (Qualified): xx mm – xx mm (based on the PQR)
Root Gap: 2–3 mm; Bevel Angle: 60° included; Backing: Optional (SS backing or GTAW root)
4. Filler Metal:
Primary Choice: ER309L / E309L (for welding); Alternative (for critical service): ERNiCr-3 (Inconel 82)
GTAW: ER 309L / ER NiCr-3; SMAW: E 309L / ENiCrFe-3; GMAW: ER309L
(309L acts as a buffer to handle dilution & prevent cracking; Ni-base reduces risk of martensite cracking)
5. Welding Parameters: GTAW (root) Polarity: DCEN ; Shielding gas: Argon (99.99%) Flow rate: 10–15 L/min
SMAW (fill/cap).Polarity: DCEP; GMAW (Optional) Mode: Spray / Pulse; Gas: Ar + 2–5% CO₂ or Ar + 2% O₂
6.Preheat & Inter-pass Temperature: Preheat 200-300 degC (for SS 410 to avoid cracking); Inter-pass 250 deg.C.
7. PWHT (for SS 410): SR at 650-700 deg C; Holding time- 1hr / 25 mm thick; Cooling- Controlled furnace cooling.
8. Special Technique: Buttering recommended on SS 410 side with ER309L to void cracking; Stringer beads preferred (no weaving)
9. Inspection & Testing: 100% VT+ PT + RT / UT – As per the requirement; Hardness check (important on 410 side & HAZ)
Trust above details will help you to prepare your WPS & PQR.
Sridhar.
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--On Tue, 17 Mar 2026 at 15:39, Md Usman Ghani <mdushmanghani@gmail.com> wrote:
Just for clarificationCan any one share, WPS, for ss410 to SS316,
--On Mon, 2 Mar, 2026, 12:39 pm Sajeersayed Ali, <sajeersayed@gmail.com> wrote:
5.2.2 Combination of WPSs. A combination of qualified and prequalified WPSs may be used without qualification
of the combination, provided the limitation of essential variables applicable to each process is observed.
--On Mon, Mar 2, 2026 at 12:26 PM praba karan <prabakaran776@gmail.com> wrote:
Dear experts,
For procedure qualification as per ASME SEC IX- "Multiple PQRs may support one WPS",
Likewise can we follow the same practice in AWS also? Because which is not mentioned directly on the code that we can use multiple PQRs to support one WPS.(And I'm not using prequalified WPS)
Thanks & regardsPrabaharan--
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