Steel ZG30CrMnSi Q&T 38-42HRC vs ZG30CrMnSi-SR
Steel · ZG30CrMnSi temper comparison
ZG30CrMnSi Q&T 38-42HRC and ZG30CrMnSi-SR are two conditions of the same steel grade, ZG30CrMnSi: Q&T 38-42HRC versus SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. ZG30CrMnSi Q&T 38-42HRC is the stronger of the two: yield strength 1,050 MPa (152 ksi) against 440 MPa (63.8 ksi) for ZG30CrMnSi-SR, about 139% more; tensile strength follows at 1,250 MPa (181 ksi) vs 690 MPa (100 ksi). In exchange, ZG30CrMnSi-SR is the more ductile: elongation 13% versus 7% for ZG30CrMnSi Q&T 38-42HRC, and ZG30CrMnSi Q&T 38-42HRC is harder (375 HB vs 205 HB). ZG30CrMnSi-SR runs hotter in service (400°C vs 200°C continuous). On the shop floor, ZG30CrMnSi-SR machines more easily (fair vs poor) and ZG30CrMnSi-SR welds better (fair vs not recommended).
ZG30CrMnSi Q&T 38-42HRCChoose it when strength drives the design.
ZG30CrMnSi-SRChoose it when the part is bent, formed or impact-loaded, or when the part sees heat.
ZG30CrMnSi Q&T 38-42HRC vs ZG30CrMnSi-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.
ZG30CrMnSi Q&T 38-42HRCZG30CrMnSi-SR
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Fatigue Strength (Endurance Limit)
Fracture Toughness (K_IC)
Charpy V-Notch Impact (RT)
Hardness, Brinell
Same in both: Elastic (Young's) Modulus 205 GPa29.7 Msi · Shear Modulus 80 GPa11.6 Msi · Bulk Modulus 160 GPa23.2 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Same in both: Density 7.8 g/cm³0.28 lb/in³ · Melting Point (Solidus) 1,425°C2,597 °F · Liquidus Temperature 1,490°C2,714 °F
Thermal
How each material carries heat and how hot it can run.
Max Service Temperature (continuous)
Same in both: Thermal Conductivity 40 W/m·K23.1 BTU/hr·ft·°F · Specific Heat Capacity 470 J/kg·K0.11 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 12.3 µm/m·K6.8 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -40°C-40 °F
Electrical
Conductivity and insulation.
Same in both: Electrical Resistivity 2.3×10⁻⁷ Ω·m9.06 µΩ·in
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Same in both: Corrosion Resistance 12 / 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: Castability 60 / 100 · Brazeability / Solderability 40 / 100 · Polishability 50 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 25 MJ/kg10,748 BTU/lb · Embodied Carbon (primary production) 2.1 kg CO₂/kg · Embodied Water 45 L/kg5.4 gal/lb · Typical Recycled Content 75%
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.
ZG30CrMnSi Q&T 38-42HRC vs ZG30CrMnSi-SR — frequently asked
Is ZG30CrMnSi Q&T 38-42HRC stronger than ZG30CrMnSi-SR?
Yes. ZG30CrMnSi Q&T 38-42HRC has a typical yield strength of 1,050 MPa (152 ksi) against 440 MPa (63.8 ksi) for ZG30CrMnSi-SR — about 139% more. Tensile strength is 1,250 MPa (181 ksi) vs 690 MPa (100 ksi).
Which condition does FabDigit quote by default, Q&T 38-42HRC or SR?
N+T is the default ZG30CrMnSi condition in the FabDigit quote flow (neither Q&T 38-42HRC nor SR). 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, ZG30CrMnSi Q&T 38-42HRC or ZG30CrMnSi-SR?
ZG30CrMnSi-SR. Its machinability rates fair (46/100) against poor (22/100) for ZG30CrMnSi Q&T 38-42HRC; for welding the order is ZG30CrMnSi-SR first (fair, 37/100) then ZG30CrMnSi Q&T 38-42HRC (not recommended, 12/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in ZG30CrMnSi Q&T 38-42HRC and ZG30CrMnSi-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.