Steel P420M-SR (Stress relieved)
Heat-treated state
EN 1.8824, 10028-5
Condition after PWHT of thick or highly restrained welds; expect a small loss of yield strength, so check the design allowables.
Values for the SR condition
Other P420M tempers and conditions
P420M is listed in 6 conditions; see the grade overview at P420M.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
M | Heaviest standard TM-rolled class; use when wall thickness cannot be reduced further. | 410 | 545 | 23 | 168 HB | 10 % IACS |
M | Medium-thickness plate class; specified yield drops to 400 MPa. | 425 | 560 | 24 | 172 HB | 10 % IACS |
SRThis page Stress relieved | Condition after PWHT of thick or highly restrained welds; expect a small loss of yield strength, so check the design allowables. | 425 | 550 | 25 | 165 HB | 10 % IACS |
MDefault Thermomechanically controlled processed | Standard supply condition for ambient / mildly cold pressure-vessel service down to -20 °C. | 445 | 570 | 24 | 175 HB | 10 % IACS |
TM rolled, low-temperature quality, impact tested at -40 °C | Choose for vessels with design temperature down to about -40 °C (tighter P/S limits). | 445 | 570 | 25 | 175 HB | 10 % IACS |
TM rolled, low-temperature quality, impact tested at -50 °C | Most demanding low-temperature grade of the family, for cold-climate or cryogenic-adjacent LPG/LNG-service vessels down to about -50 °C. | 450 | 575 | 25 | 175 HB | 10 % IACS |
What is P420M-SR?
P420M-SR is P420M heat treated to SR — condition after PWHT of thick or highly restrained welds; expect a small loss of yield strength, so check the design allowables. P420M-SR has a yield strength of 425 MPa (61.6 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 52% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi). P420M-SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F). M is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 140 MPa·√m (127.4 ksi·√in), better than 94% of steel grades
- Readily welded — 86/100, better than 85% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
- Forms and bends easily — 65/100, better than 81% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
P420M-SR properties
Typical room-temperature values for P420M-SR; 22 are specific to this condition. Other listed values are P420M reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
P420M-SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,460°C (2,660 °F).
Mechanical16
P420M-SR has a yield strength of 425 MPa (61.6 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 52% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
P420M-SR is rated for continuous service to 400°C (752 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
P420M-SR conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of P420M-SR takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
P420M-SR's machinability is good (61/100, better than 87% of steel grades); weldability excellent (86/100); formability good (65/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with P420M-SR
Is P420M easy to machine?
Machines like a tough 1.5 % Mn HSLA plate — rigid setups, sharp coated carbide, moderate speeds and generous feed to avoid work hardening at drilled/bevelled edges.
Can P420M be welded?
Very good weldability with low CEV; use low-hydrogen consumables matching 420 MPa yield, control heat input to keep HAZ toughness, preheat only for heavy or restrained joints.
Can P420M be formed, bent or molded?
Cold-bendable with radii larger than mild steel; avoid hot forming or normalizing above ~580 °C because the TM-rolled strength cannot be restored by reheat treatment.
What surface finishes work on P420M?
Blast and paint, metallize or galvanize — no inherent corrosion resistance; edges from thermal cutting should be ground before coating.
P420M 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 |
|---|---|---|
| Cladle analysis, EN 10028-5 | ≤ 0.18 | 0.13 |
| Si | ≤ 0.5 | 0.3 |
| Mn | 1 – 1.7 | 1.5 |
| P≤0.025 for ML1, ≤0.020 for ML2 | ≤ 0.03 | 0.02 |
| S≤0.015 for ML1, ≤0.010 for ML2 | ≤ 0.03 | 0.01 |
| Altotal Al, grain refinement | ≥ 0.02 | 0.04 |
| NbNb+V+Ti ≤ 0.22 | ≤ 0.05 | 0.04 |
| V | ≤ 0.12 | 0.05 |
| Ti | ≤ 0.05 | 0.02 |
| Cr | ≤ 0.3 | 0.1 |
| Ni | ≤ 0.8 | 0.2 |
| Mo | ≤ 0.25 | 0.08 |
| Cu | ≤ 0.7 | 0.15 |
| N | ≤ 0.03 | 0.01 |
| Fe | balance | — |
P420M-SR — frequently asked
What is P420M-SR used for?
P420M-SR is typically used for pressure vessels, petrochemical reactors and heavy tanks. In short: thinner walls than P355M; low-CEV pressure vessel plate; good HAZ toughness.
What is the yield strength of P420M-SR?
P420M-SR has a typical yield strength of 425 MPa (61.6 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 52% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is P420M-SR easy to machine?
Reasonably — machinability is rated good (61/100, better than 87% of steel grades). Machines like a tough 1.5 % Mn HSLA plate — rigid setups, sharp coated carbide, moderate speeds and generous feed to avoid work hardening at drilled/bevelled edges.
Can P420M-SR be welded?
Yes — weldability is rated excellent (86/100). Very good weldability with low CEV; use low-hydrogen consumables matching 420 MPa yield, control heat input to keep HAZ toughness, preheat only for heavy or restrained joints.
What surface finishes work on P420M-SR?
Blast and paint, metallize or galvanize — no inherent corrosion resistance; edges from thermal cutting should be ground before coating.
Can P420M-SR be formed, bent or molded?
Cold-bendable with radii larger than mild steel; avoid hot forming or normalizing above ~580 °C because the TM-rolled strength cannot be restored by reheat treatment.
What is the maximum service temperature of P420M-SR?
P420M-SR is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between P420M-M and P420M-SR?
M is the default condition — standard supply condition for ambient / mildly cold pressure-vessel service down to -20 °C. SR: condition after PWHT of thick or highly restrained welds; expect a small loss of yield strength, so check the design allowables. Yield strength is 445 MPa in M versus 425 MPa in SR.
Sources
- EN 10028-5 — Flat products made of steels for pressure purposes: weldable fine grain steels, thermomechanically rolled — CEN (2017)
- EN 10027-2 — Numerical designation system (1.8824) — CEN (2015)
- EN 13445-3 — Unfired pressure vessels: design — CEN (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Thermomechanically rolled fine-grain pressure vessel plate datasheets (P355M–P460M family) — European plate mills (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.