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Steel HRS · finish state

Steel HRS HRPO

Properties of the HRPO condition, compared with the other HRS tempers.

Choose when you want hot-rolled price and gauge but a clean, paint- or weld-ready surface without shot blasting.

CNC machiningSheet metalStandard cost $$
Request a quote in HRS HRPOHRS overview

What is HRS HRPO?

HRS HRPO is HRS supplied in the HRPO condition — choose when you want hot-rolled price and gauge but a clean, paint- or weld-ready surface without shot blasting. HRS HRPO has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 90% of steel grades. Elongation at break is 26% and the elastic modulus is 200 GPa (29 Msi). HRS HRPO has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F). HR is the default condition FabDigit quotes; HRPO is available on request or by drawing note.

Advantages

  • Readily welded — 97/100, better than 100% of steel grades
  • Conducts heat well — 51.9 W/m·K (30 BTU/hr·ft·°F), better than 96% of steel grades
  • High electrical conductivity — 10.8 % IACS, better than 94% of steel grades
  • Easy to machine — 62/100, better than 89% of steel grades
  • Forms and bends easily — 72/100, better than 88% of steel grades

Limitations

  • Low strength — 280 MPa (40.6 ksi), worse than 90% of steel grades

HRS HRPO properties

Typical room-temperature values for HRS HRPO — 10 properties are specific to this condition; the rest are grade-level values shared by every HRS temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.

Physical3

HRS HRPO has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,495°C (2,723 °F).

Density7.85 g/cm³0.28 lb/in³
Melting Point (Solidus)1,495°C2,723 °F
Liquidus Temperature1,525°C2,777 °F

Mechanical16

HRS HRPO has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 90% of steel grades. Elongation at break is 26% and the elastic modulus is 200 GPa (29 Msi).

Elastic (Young's) Modulus200 GPa29 Msi
Shear Modulus79 GPa11.5 Msi
Bulk Modulus160 GPa23.2 Msi
Poisson's Ratio0.29
Tensile Strength (Ultimate)440 MPa63.8 ksi
Yield Strength (0.2% offset)280 MPa40.6 ksi
Elongation at Break26%
Reduction in Area50%
Compressive Strength285 MPa41.3 ksi
Shear Strength270 MPa39.2 ksi
Fatigue Strength (Endurance Limit)200 MPa29 ksi
Fracture Toughness (K_IC)80 MPa·√m72.8 ksi·√in
Charpy V-Notch Impact (RT)40 J29.5 ft·lbf
Hardness, Brinell125 HB
Hardness, Rockwell B68 HRB
Hardness, Vickers137 HV

Thermal6

HRS HRPO is rated for continuous service to 400°C (752 °F). It conducts heat at 51.9 W/m·K (30 BTU/hr·ft·°F), better than 96% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).

Thermal Conductivity51.9 W/m·K30 BTU/hr·ft·°F
Specific Heat Capacity480 J/kg·K0.11 BTU/lb·°F
Thermal Expansion (CTE, 20–100 °C)11.9 µm/m·K6.6 µin/in·°F
Latent Heat of Fusion247 J/g106 BTU/lb
Max Service Temperature (continuous)400°C752 °F
Min Service Temperature-20°C-4 °F

Electrical3

HRS HRPO conducts electricity at 10.8 % IACS, better than 94% of steel grades.

Electrical Conductivity10.8 % IACS
Electrical Resistivity1.6×10⁻⁷ Ω·m6.3 µΩ·in
Magnetic Responseferromagnetic

Chemical & Environmental3

Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.

Galvanic Potential (seawater, vs SCE)-0.65 V
Corrosion ResistanceNot recommended11/100
Chemical Resistance SummaryRusts freely in humid air, water and chlorides; requires paint, oil, phosphate or zinc coating. Resists dry gases, most oils and alkalis (pH>10); attacked rapidly by dilute acids and salt spray.

Sustainability4

Producing a kilogram of HRS HRPO takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 25%.

Embodied Energy (primary production)25 MJ/kg10,748 BTU/lb
Embodied Carbon (primary production)2.1 kg CO₂/kg
Embodied Water40 L/kg4.8 gal/lb
Typical Recycled Content25%

Manufacturability7

HRS HRPO's machinability is good (62/100, better than 89% of steel grades); weldability excellent (97/100); formability very good (72/100).

MachinabilityGood62/100
Machinability Rating (AISI 1212 = 100 %)60%
WeldabilityExcellent97/100
Formability (cold)Very good72/100
Brazeability / SolderabilityVery good70/100
PolishabilityFair50/100
Anodizing Responsen/a — ferrous alloy; use zinc plating, hot-dip galvanizing, phosphate + paint or black oxide instead

Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.

Other HRS tempers and conditions

HRS is also supplied in 5 other conditions. The full side-by-side table is on the HRS overview.

Working with HRS HRPO

Is HRS easy to machine?

Free and easy at HSS/carbide speeds but gummy — use positive rake, sharp tooling and coolant; expect a poorer finish than cold-rolled or leaded grades and remove mill scale first to protect edges.

Can HRS be welded?

Prequalified for essentially all processes (SMAW/GMAW/FCAW/RSW) with E70/ER70S-6 consumables, no preheat below ~38 mm at RT; grind off scale, oil or zinc coating before welding and ventilate zinc fume.

Can HRS be formed, bent or molded?

Bends and rolls readily cold (min bend radius ≈ 1–1.5 t hot rolled, 0.5–1 t cold rolled); hot-rolled scale can crack and mark dies, and springback is low.

What surface finishes work on HRS?

No anodizing — blast or pickle then prime; typical finishes are phosphate + powder coat/e-coat, zinc plating, hot-dip galvanizing or black oxide/oil for temporary protection.

HRS 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.

ElementSpec limit (wt %)Nominal
CA36 plate ≤0.26; A1011 CS / Q235B typically 0.12–0.20≤ 0.260.18
Mnwider range for thicker plate0.3 – 1.20.7
Si0.15–0.40 when silicon-killed≤ 0.40.2
P≤ 0.040.02
S≤ 0.050.02
Cu0.20 min if copper-bearing grade specified≤ 0.20.05
Febalance, residual Cr/Ni/Mo typically <0.1 eachbalance—

HRS HRPO — frequently asked

What is HRS HRPO used for?

HRS HRPO is typically used for structural plate and base plates, bracket weldments, welded machine frames and skids, sheet-metal enclosures and panels, formed channels, angles and gussets and machine guards and platform floor plate. In short: workhorse hot-rolled plate.

What is the yield strength of HRS HRPO?

HRS HRPO has a typical yield strength of 280 MPa (40.6 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 90% of steel grades. Strength varies by condition: see the 6 listed tempers.

Is HRS HRPO easy to machine?

Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Free and easy at HSS/carbide speeds but gummy — use positive rake, sharp tooling and coolant; expect a poorer finish than cold-rolled or leaded grades and remove mill scale first to protect edges.

Can HRS HRPO be welded?

Yes — weldability is rated excellent (97/100). Prequalified for essentially all processes (SMAW/GMAW/FCAW/RSW) with E70/ER70S-6 consumables, no preheat below ~38 mm at RT; grind off scale, oil or zinc coating before welding and ventilate zinc fume.

What surface finishes work on HRS HRPO?

No anodizing — blast or pickle then prime; typical finishes are phosphate + powder coat/e-coat, zinc plating, hot-dip galvanizing or black oxide/oil for temporary protection.

Can HRS HRPO be formed, bent or molded?

Bends and rolls readily cold (min bend radius ≈ 1–1.5 t hot rolled, 0.5–1 t cold rolled); hot-rolled scale can crack and mark dies, and springback is low.

What is the maximum service temperature of HRS HRPO?

HRS HRPO 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 HRS-HR and HRS-CR?

HR is the default condition — cheapest structural condition — pick for weldments, frames, brackets and plate where dimensional tolerance and surface finish don't matter. CR: pick for tight thickness tolerance, smooth paint-ready surface and better machined finish; costs more and has less ductility than HR. Yield strength is 285 MPa in HR versus 350 MPa in CR.

Can FabDigit make parts in HRS HRPO?

Yes — HRS HRPO is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.

Sources

  1. ASTM A36/A36M Carbon Structural Steel — ASTM International (2019)
  2. ASTM A1011/A1011M Hot-Rolled Sheet and Strip, CS/SS/HSLAS — ASTM International (2018)
  3. ASTM A1008/A1008M Cold-Rolled Sheet, CS/SS/HSLAS — ASTM International (2021)
  4. ASTM A653/A653M Zinc-Coated (Galvanized/Galvannealed) Sheet — ASTM International (2020)
  5. GB/T 700 (Q235B) — SAC / (2006)
  6. ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
  7. Machinery's Handbook, 31st ed. (machinability ratings) — Industrial Press (2020)
  8. worldsteel LCI data for steel products — World Steel Association (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.