Steel E155 +A vs E155 +SR
Steel · E155 temper comparison
E155 +A and E155 +SR are two conditions of the same steel grade, E155: +A (annealed) versus +SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. E155 +SR is the stronger of the two: yield strength 280 MPa (40.6 ksi) against 180 MPa (26.1 ksi) for E155 +A, about 56% more; tensile strength follows at 390 MPa (56.6 ksi) vs 300 MPa (43.5 ksi). In exchange, E155 +A is the more ductile: elongation 35% versus 18% for E155 +SR, and E155 +SR is harder (125 HB vs 95 HB). On the shop floor, E155 +SR machines more easily (good vs fair).
E155 +AChoose it when the part is bent, formed or impact-loaded.
E155 +SRChoose it when strength drives the design, or when the part is machined in volume.
E155 +A vs E155 +SR: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Shear Strength
Fatigue Strength (Endurance Limit)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 210 GPa30.5 Msi · Shear Modulus 81 GPa11.7 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29 · Reduction in Area 65% · Compressive Strength 180 MPa26.1 ksi · Fracture Toughness (K_IC) 110 MPa·√m100 ksi·√in · Charpy V-Notch Impact (RT) 60 J44.3 ft·lbf
Physical
Density and transition temperatures.
Same in both: Density 7.85 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,495°C2,723 °F · Liquidus Temperature 1,530°C2,786 °F
Thermal
How each material carries heat and how hot it can run.
Same in both: Thermal Conductivity 52 W/m·K30 BTU/hr·ft·°F · Specific Heat Capacity 475 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12 µm/m·K6.7 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Max Service Temperature (continuous) 350°C662 °F · Min Service Temperature -20°C-4 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 10.8 % IACS · Electrical Resistivity 1.6×10⁻⁷ Ω·m6.3 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Galvanic Potential (seawater, vs SCE) -0.61 V · Corrosion Resistance 10 / 100
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Same in both: Brazeability / Solderability 75 / 100 · Polishability 45 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 24 MJ/kg10,318 BTU/lb · Embodied Carbon (primary production) 1.9 kg CO₂/kg · Embodied Water 45 L/kg5.4 gal/lb · Typical Recycled Content 30%
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
E155 +A vs E155 +SR — frequently asked
Is E155 +SR stronger than E155 +A?
Yes. E155 +SR has a typical yield strength of 280 MPa (40.6 ksi) against 180 MPa (26.1 ksi) for E155 +A — about 56% more. Tensile strength is 390 MPa (56.6 ksi) vs 300 MPa (43.5 ksi).
Which condition does FabDigit quote by default, +A or +SR?
+A is the default E155 condition in the FabDigit quote flow. The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, E155 +A or E155 +SR?
E155 +SR. Its machinability rates good (60/100) against fair (46/100) for E155 +A.
Ready to make it?
Upload a CAD file and FabDigit prices the part in E155 +A and E155 +SR side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.