Steel P355QH1 QT-HIC
Certified grade
EN 1.0571, 10028-6
QT-HIC = q+T, HIC / sour-service tested
Low-sulphur, calcium-treated, HIC-tested plate for wet H2S separators and amine vessels.
Values for the QT-HIC condition
Other P355QH1 tempers and conditions
P355QH1 is listed in 6 conditions; see the grade overview at P355QH1.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Q+T | Maximum practical section; use where full hardenability and mid-thickness toughness must still be certified. | 355 | 520 | 24 | 160 HB | 9 % IACS |
simulated post-weld heat treatment (stress relieved) | Ordered when the vessel will be stress-relieved at 550–620 °C; properties certified after simulated PWHT cycle. | 375 | 530 | 26 | 165 HB | 9 % IACS |
Q+T | Heavy plate for thick-wall shells and forgings-substitute flanges; strength de-rated for section size. | 380 | 540 | 24 | 168 HB | 9 % IACS |
QT-HICThis page Q+T, HIC / sour-service tested | Low-sulphur, calcium-treated, HIC-tested plate for wet H2S separators and amine vessels. | 395 | 555 | 25 | 11 HRC | 9 % IACS |
QTDefault Quenched and tempered | Standard delivery condition for plate up to 50 mm; full 355 MPa minimum yield with -20 °C impact guarantee. | 400 | 560 | 25 | 175 HB | 9 % IACS |
Q+T with Z35 through-thickness ductility | Same heat treatment plus guaranteed 35 % through-thickness reduction of area for heavily restrained T-joints and nozzle reinforcements. | 400 | 560 | 24 | 175 HB | 9 % IACS |
What is P355QH1 QT-HIC?
P355QH1 QT-HIC is P355QH1 in a QT-HIC certified grade — low-sulphur, calcium-treated, HIC-tested plate for wet H2S separators and amine vessels. P355QH1 QT-HIC has a yield strength of 395 MPa (57.3 ksi) and a tensile strength of 555 MPa (80.5 ksi) — weaker than 63% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi). P355QH1 QT-HIC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). QT is the default condition FabDigit quotes; QT-HIC is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 160 MPa·√m (145.6 ksi·√in), better than 98% of steel grades
- Readily welded — 78/100, better than 78% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
P355QH1 QT-HIC properties
Typical room-temperature values for P355QH1 QT-HIC; 23 are specific to this condition. Other listed values are P355QH1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
P355QH1 QT-HIC has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
P355QH1 QT-HIC has a yield strength of 395 MPa (57.3 ksi) and a tensile strength of 555 MPa (80.5 ksi) — weaker than 63% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
P355QH1 QT-HIC 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
P355QH1 QT-HIC conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of P355QH1 QT-HIC 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
P355QH1 QT-HIC's machinability is fair (53/100, better than 53% of steel grades); weldability very good (78/100); formability good (55/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with P355QH1 QT-HIC
Is P355QH1 easy to machine?
Machines like a 180 HB Q&T C-Mn steel — carbide inserts, moderate speeds, rigid setups; avoid heavy grinding heat that tempers the surface.
Can P355QH1 be welded?
Good weldability with low-hydrogen SMAW/SAW/FCAW consumables; check CEV, preheat 100–150 °C above ~40 mm and limit heat input to preserve HAZ toughness; PWHT 550–620 °C, below the tempering temperature.
Can P355QH1 be formed, bent or molded?
Cold-roll shells with generous bend radii (≥3t) or hot-form at 850–950 °C followed by re-quench and temper, since hot forming destroys the delivered condition.
What surface finishes work on P355QH1?
Shot-blast to Sa 2½ and apply epoxy/zinc-rich paint, or clad/weld-overlay with stainless or Alloy 625 for corrosive process sides; no anodizing possible.
P355QH1 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 10028-6 | ≤ 0.16 | 0.14 |
| Si | ≤ 0.5 | 0.3 |
| Mn | 0.8 – 1.7 | 1.4 |
| PQH grade | ≤ 0.03 | 0.01 |
| SQH grade; lower for HIC plate | ≤ 0.01 | 0 |
| Altotal Al, grain refinement | ≥ 0.02 | 0.04 |
| Cr | ≤ 0.3 | 0.15 |
| Ni | ≤ 0.5 | 0.2 |
| Mo | ≤ 0.25 | 0.1 |
| Cu | ≤ 0.3 | 0.1 |
| Nbmicroalloy | ≤ 0.05 | 0.03 |
| Timicroalloy | ≤ 0.05 | 0.02 |
| Vmicroalloy | ≤ 0.08 | 0.03 |
| Bhardenability, thick plate | ≤ 0.01 | 0 |
| N | ≤ 0.02 | 0.01 |
| Fe | balance | — |
P355QH1 QT-HIC — frequently asked
What is P355QH1 QT-HIC used for?
P355QH1 QT-HIC is typically used for high-pressure vessels, thick-wall reactors, heavy boiler drums and chemical process equipment. In short: highest-strength 355 vessel plate; thinner walls, heavier sections; Q&T condition limits fabrication.
What is the yield strength of P355QH1 QT-HIC?
P355QH1 QT-HIC has a typical yield strength of 395 MPa (57.3 ksi) and a tensile strength of 555 MPa (80.5 ksi) — weaker than 63% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is P355QH1 QT-HIC easy to machine?
Reasonably — machinability is rated fair (53/100, better than 53% of steel grades). Machines like a 180 HB Q&T C-Mn steel — carbide inserts, moderate speeds, rigid setups; avoid heavy grinding heat that tempers the surface.
Can P355QH1 QT-HIC be welded?
Yes — weldability is rated very good (78/100). Good weldability with low-hydrogen SMAW/SAW/FCAW consumables; check CEV, preheat 100–150 °C above ~40 mm and limit heat input to preserve HAZ toughness; PWHT 550–620 °C, below the tempering temperature.
What surface finishes work on P355QH1 QT-HIC?
Shot-blast to Sa 2½ and apply epoxy/zinc-rich paint, or clad/weld-overlay with stainless or Alloy 625 for corrosive process sides; no anodizing possible.
Can P355QH1 QT-HIC be formed, bent or molded?
Cold-roll shells with generous bend radii (≥3t) or hot-form at 850–950 °C followed by re-quench and temper, since hot forming destroys the delivered condition.
What is the maximum service temperature of P355QH1 QT-HIC?
P355QH1 QT-HIC 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 P355QH1-QT and P355QH1 QT-PWHT?
QT is the default condition — standard delivery condition for plate up to 50 mm; full 355 MPa minimum yield with -20 °C impact guarantee. QT-PWHT: ordered when the vessel will be stress-relieved at 550–620 °C; properties certified after simulated PWHT cycle. Yield strength is 400 MPa in QT versus 375 MPa in QT-PWHT.
Sources
- EN 10028-6 Flat products for pressure purposes — Weldable fine grain steels, quenched and tempered — CEN (2017)
- ASTM A537/A537M Heat-Treated Carbon-Manganese-Silicon Steel Plates for Pressure Vessels — ASTM (2020)
- GB/T 713 Steel plates for boilers and pressure vessels (Q345R) — SAC (2014)
- EN 10164 Steel products with improved deformation properties perpendicular to the surface — CEN (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Quenched and tempered pressure vessel plate datasheets (Dillinger / Industeel / voestalpine) — various 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.