Stainless Steel ER420 PWHT-400
Heat-treated state
UNS S42080
PWHT-400 = pWHT 350–450 °C
Compromise temper for tools needing ~45 HRC; avoid holding near 475 °C where embrittlement and carbide sensitisation begin.
Values for the PWHT-400 condition
Other ER420 tempers and conditions
ER420 is listed in 6 conditions; see the grade overview at ER420.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Use when the whole repaired part is fully annealed for extensive machining before final hardening. | 450 | 760 | 18 | 215 HB | — |
PWHT 600–700 °C | Choose when the repair must be machined or when a tougher, less crack-sensitive deposit is required at moderate hardness. | 850 | 1,050 | 13 | 33 HRC | — |
PWHT-400This page PWHT 350–450 °C | Compromise temper for tools needing ~45 HRC; avoid holding near 475 °C where embrittlement and carbide sensitisation begin. | 1,250 | 1,500 | 7 | 45 HRC | 3.2 % IACS |
AWDefault As-welded deposit | Default condition straight off the arc — maximum hardness for wear surfacing, but brittle and crack-prone until tempered. | 1,350 | 1,650 | 3 | 50 HRC | — |
PWHT 200–300 °C | Pick when maximum wear hardness must be kept but hydrogen/quench stresses need relieving on hardfaced surfaces. | 1,450 | 1,700 | 5 | 49 HRC | 3.1 % IACS |
Q&T | Full re-heat-treatment of the welded assembly to restore uniform cutlery/die hardness of 52–56 HRC. | 1,550 | 1,850 | 4 | 54 HRC | — |
What is ER420 PWHT-400?
ER420 PWHT-400 is ER420 heat treated to PWHT-400 — compromise temper for tools needing ~45 HRC; avoid holding near 475 °C where embrittlement and carbide sensitisation begin. ER420 PWHT-400 has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 99% of stainless steel grades. Elongation at break is 7% and the elastic modulus is 200 GPa (29 Msi). ER420 PWHT-400 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,450°C (2,642 °F). AW is the default condition FabDigit quotes; PWHT-400 is available on request or by drawing note.
Advantages
- High electrical conductivity — 3.2 % IACS, better than 100% of stainless steel grades
- High strength — 1,250 MPa (181 ksi), better than 99% of stainless steel grades
- Conducts heat well — 25.4 W/m·K (14.7 BTU/hr·ft·°F), better than 95% of stainless steel grades
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
Limitations
- Limited ductility — 7%, worse than 99% of stainless steel grades
- Low fracture toughness — 28 MPa·√m (25.5 ksi·√in), worse than 99% of stainless steel grades
- Difficult to machine — 18/100, worse than 99% of stainless steel grades
- Needs corrosion protection — 38/100, worse than 95% of stainless steel grades
- Limited formability — 13/100, worse than 92% of stainless steel grades
ER420 PWHT-400 properties
Typical room-temperature values for ER420 PWHT-400; 22 are specific to this condition. Other listed values are ER420 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
ER420 PWHT-400 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
ER420 PWHT-400 has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 99% of stainless steel grades. Elongation at break is 7% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
ER420 PWHT-400 is rated for continuous service to 350°C (662 °F). It conducts heat at 25.4 W/m·K (14.7 BTU/hr·ft·°F), better than 95% of stainless steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
ER420 PWHT-400 conducts electricity at 3.2 % IACS, better than 100% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 95% of stainless steel grades.
Sustainability4
Producing a kilogram of ER420 PWHT-400 takes about 53 MJ of energy and emits 4.6 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
ER420 PWHT-400's machinability is poor (18/100, worse than 99% of stainless steel grades); weldability fair (38/100); formability not recommended (13/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ER420 PWHT-400
Is ER420 easy to machine?
As-welded deposit at ~50 HRC is essentially grind-only; high-temper (650 °C) or full anneal first if turning/milling is needed, then re-harden.
Can ER420 be welded?
GTAW/GMAW/SAW on 410/420 base metal; preheat and interpass 200–300 °C, slow cool, then temper or anneal immediately to avoid hydrogen cracking — never leave untempered overnight.
Can ER420 be formed, bent or molded?
Not a wrought product form — supplied as spooled wire or cut TIG rod; the martensitic deposit has no useful cold formability.
What surface finishes work on ER420?
Grind and polish to a fine finish for wear/sealing surfaces, then passivate (nitric or citric) to restore the chromium oxide film; hard chrome or nitriding may be added for extra wear life.
ER420 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CAWS A5.9 ER420 | 0.25 – 0.4 | 0.32 |
| Cr | 12 – 14 | 13 |
| Mn | ≤ 0.6 | 0.45 |
| Si | ≤ 0.5 | 0.35 |
| Ni | ≤ 0.75 | 0.3 |
| Mo | ≤ 0.75 | 0.2 |
| Cu | ≤ 0.75 | 0.15 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Fe | balance | — |
ER420 PWHT-400 — frequently asked
What is ER420 PWHT-400 used for?
ER420 PWHT-400 is typically used for cutlery and blade repair welding, hardenable tool component joining, die and mould weld build-up, plastic-mould steel repair, wear surface overlay on 420 shafts and valve seat and sealing face rebuilding. In short: hardest martensitic stainless filler; 50 HRC as-welded; grind-only after welding.
What is the yield strength of ER420 PWHT-400?
ER420 PWHT-400 has a typical yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 99% of stainless steel grades. Strength varies by condition: see the 6 listed tempers.
Is ER420 PWHT-400 easy to machine?
Not especially — machinability is rated poor (18/100, worse than 99% of stainless steel grades). As-welded deposit at ~50 HRC is essentially grind-only; high-temper (650 °C) or full anneal first if turning/milling is needed, then re-harden.
Can ER420 PWHT-400 be welded?
With care — weldability is rated fair (38/100). GTAW/GMAW/SAW on 410/420 base metal; preheat and interpass 200–300 °C, slow cool, then temper or anneal immediately to avoid hydrogen cracking — never leave untempered overnight.
What surface finishes work on ER420 PWHT-400?
Grind and polish to a fine finish for wear/sealing surfaces, then passivate (nitric or citric) to restore the chromium oxide film; hard chrome or nitriding may be added for extra wear life.
Can ER420 PWHT-400 be formed, bent or molded?
Not a wrought product form — supplied as spooled wire or cut TIG rod; the martensitic deposit has no useful cold formability.
What is the maximum service temperature of ER420 PWHT-400?
ER420 PWHT-400 is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ER420-AW and ER420-ANN?
AW is the default condition — default condition straight off the arc — maximum hardness for wear surfacing, but brittle and crack-prone until tempered. ANN: use when the whole repaired part is fully annealed for extensive machining before final hardening. Yield strength is 1,350 MPa in AW versus 450 MPa in ANN.
Sources
- AWS A5.9/A5.9M — Bare Stainless Steel Welding Electrodes and Rods — American Welding Society (2017)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol.6 — Welding, Brazing and Soldering — ASM International (1993)
- Martensitic stainless filler metal ER420 data sheets — Böhler Welding / Metrode / Lincoln Electric (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.