Titanium Ti Grade 21-ST vs Ti Grade 21 STA-M
Titanium · Ti Grade 21 temper comparison
Ti Grade 21-ST and Ti Grade 21 STA-M are two conditions of the same titanium grade, Ti Grade 21: ST (solution annealed) versus STA-M (STA). The chemistry is identical, so every difference below comes from the condition. Ti Grade 21 STA-M is the stronger of the two: yield strength 1,150 MPa (167 ksi) against 805 MPa (117 ksi) for Ti Grade 21-ST, about 43% more; tensile strength follows at 1,220 MPa (177 ksi) vs 830 MPa (120 ksi). In exchange, Ti Grade 21-ST is the more ductile: elongation 18% versus 9% for Ti Grade 21 STA-M, and Ti Grade 21 STA-M is harder (39 HRC vs 28 HRC). Ti Grade 21 STA-M is stiffer (100 GPa vs 79 GPa) and Ti Grade 21 STA-M runs hotter in service (565°C vs 425°C continuous). On the shop floor, Ti Grade 21-ST welds better (very good vs fair).
Ti Grade 21-STChoose it when the part is bent, formed or impact-loaded, or when it will be welded.
Ti Grade 21 STA-MChoose it when strength drives the design, or when the part sees heat.
Ti Grade 21-ST vs Ti Grade 21 STA-M: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all titanium 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 titanium 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.
Ti Grade 21-STTi Grade 21 STA-M
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Elastic (Young's) Modulus
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Rockwell C
Hardness, Vickers
Same in both: Shear Modulus 31 GPa4.5 Msi · Bulk Modulus 105 GPa15.2 Msi · Poisson's Ratio 0.33 · Compressive Strength 830 MPa120 ksi
Physical
Density and transition temperatures.
Same in both: Density 4.94 g/cm³0.18 lb/in³ · Melting Point (Solidus) 1,600°C2,912 °F · Liquidus Temperature 1,660°C3,020 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 7.6 W/m·K4.4 BTU/hr·ft·°F · Specific Heat Capacity 500 J/kg·K0.12 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 8.6 µm/m·K4.8 µin/in·°F · Latent Heat of Fusion 360 J/g155 BTU/lb · Min Service Temperature -196°C-321 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Conductivity 1.3 % IACS · Electrical Resistivity 1.35×10⁻⁶ Ω·m53.1 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Same in both: Galvanic Potential (seawater, vs SCE) -0.1 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 30 / 100 · Brazeability / Solderability 45 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 700 MJ/kg300,946 BTU/lb · Embodied Carbon (primary production) 48 kg CO₂/kg · Embodied Water 900 L/kg108 gal/lb · Typical Recycled Content 25%
Strength versus weight
Yield strength against density for every titanium grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Ti Grade 21-ST vs Ti Grade 21 STA-M — frequently asked
Is Ti Grade 21 STA-M stronger than Ti Grade 21-ST?
Yes. Ti Grade 21 STA-M has a typical yield strength of 1,150 MPa (167 ksi) against 805 MPa (117 ksi) for Ti Grade 21-ST — about 43% more. Tensile strength is 1,220 MPa (177 ksi) vs 830 MPa (120 ksi).
Which condition does FabDigit quote by default, ST or STA-M?
ST is the default Ti Grade 21 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, Ti Grade 21-ST or Ti Grade 21 STA-M?
Ti Grade 21-ST. Its machinability rates poor (20/100) against not recommended (14/100) for Ti Grade 21 STA-M; for welding the order is Ti Grade 21-ST first (very good, 75/100) then Ti Grade 21 STA-M (fair, 50/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in Ti Grade 21-ST and Ti Grade 21 STA-M 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.