Stainless Steel XM-21 1/4H vs XM-21 3/4H
Stainless Steel · XM-21 temper comparison
XM-21 1/4H and XM-21 3/4H are two conditions of the same stainless steel grade, XM-21: 1/4H (quarter hard) versus 3/4H (three-quarter hard). The chemistry is identical, so every difference below comes from the condition. XM-21 3/4H is the stronger of the two: yield strength 960 MPa (139 ksi) against 650 MPa (94.3 ksi) for XM-21 1/4H, about 48% more; tensile strength follows at 1,230 MPa (178 ksi) vs 900 MPa (131 ksi). In exchange, XM-21 1/4H is the more ductile: elongation 18% versus 8% for XM-21 3/4H, and XM-21 3/4H is harder (345 HB vs 260 HB). XM-21 1/4H runs hotter in service (400°C vs 340°C continuous). On the shop floor, XM-21 1/4H welds better (very good vs good).
XM-21 1/4HChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
XM-21 3/4HChoose it when strength drives the design.
XM-21 1/4H vs XM-21 3/4H: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all stainless 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 stainless 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
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell B
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 193 GPa28 Msi · Shear Modulus 77 GPa11.2 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Same in both: Density 7.9 g/cm³0.29 lb/in³ · Melting Point (Solidus) 1,400°C2,552 °F · Liquidus Temperature 1,450°C2,642 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 16.2 W/m·K9.4 BTU/hr·ft·°F · Specific Heat Capacity 500 J/kg·K0.12 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 16.5 µm/m·K9.2 µin/in·°F · Latent Heat of Fusion 275 J/g118 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 2.4 % IACS · Electrical Resistivity 7.4×10⁻⁷ Ω·m29.1 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.08 V
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: Castability 40 / 100 · Brazeability / Solderability 65 / 100 · Polishability 80 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 53 MJ/kg22,786 BTU/lb · Embodied Carbon (primary production) 4.5 kg CO₂/kg · Embodied Water 120 L/kg14.4 gal/lb · Typical Recycled Content 70%
Strength versus weight
Yield strength against density for every stainless steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
XM-21 1/4H vs XM-21 3/4H — frequently asked
Is XM-21 3/4H stronger than XM-21 1/4H?
Yes. XM-21 3/4H has a typical yield strength of 960 MPa (139 ksi) against 650 MPa (94.3 ksi) for XM-21 1/4H — about 48% more. Tensile strength is 1,230 MPa (178 ksi) vs 900 MPa (131 ksi).
Which condition does FabDigit quote by default, 1/4H or 3/4H?
Annealed is the default XM-21 condition in the FabDigit quote flow (neither 1/4H nor 3/4H). 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, XM-21 1/4H or XM-21 3/4H?
XM-21 1/4H, by a small margin. Both rate poor for machinability — 33/100 against 26/100 for XM-21 3/4H; for welding the order is XM-21 1/4H first (very good, 78/100) then XM-21 3/4H (good, 65/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in XM-21 1/4H and XM-21 3/4H 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.