Steel ZG20CrMo-SR (Stress relieved)
Heat-treated state
Applied after weld repair or heavy machining of N+T castings to restore dimensional stability and weld-zone toughness.
Values for the SR condition
Other ZG20CrMo tempers and conditions
ZG20CrMo is listed in 5 conditions; see the grade overview at ZG20CrMo.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for maximum machinability and lowest residual stress before heavy machining or repair welding. | 255 | 470 | 24 | 145 HB | 8 % IACS |
As fabricated | Rough/non-pressure parts only; coarse as-cast structure with low toughness — pressure service requires heat treatment. | 260 | 500 | 13 | 170 HB | 7.8 % IACS |
SRThis page Stress relieved | Applied after weld repair or heavy machining of N+T castings to restore dimensional stability and weld-zone toughness. | 280 | 510 | 22 | 155 HB | 7.8 % IACS |
N+TDefault Normalized and tempered | Standard delivery condition for pressure-vessel and valve castings; balanced strength, toughness and elevated-temperature stability. | 285 | 520 | 21 | 160 HB | — |
Quenched and tempered | Pick when higher yield strength and low-temperature toughness are needed in thinner sections, e.g. high-pressure valve bodies. | 470 | 660 | 17 | 18 HRC | — |
What is ZG20CrMo-SR?
ZG20CrMo-SR is ZG20CrMo heat treated to SR — applied after weld repair or heavy machining of N+T castings to restore dimensional stability and weld-zone toughness. ZG20CrMo-SR has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 90% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi). ZG20CrMo-SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F). N+T is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- High service temperature — 510°C (950 °F), better than 92% of steel grades
Limitations
- Low strength — 280 MPa (40.6 ksi), worse than 90% of steel grades
- Limited formability — 14/100, worse than 90% of steel grades
ZG20CrMo-SR properties
Typical room-temperature values for ZG20CrMo-SR; 22 are specific to this condition. Other listed values are ZG20CrMo reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
ZG20CrMo-SR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,450°C (2,642 °F).
Mechanical16
ZG20CrMo-SR has a yield strength of 280 MPa (40.6 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 90% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
ZG20CrMo-SR is rated for continuous service to 510°C (950 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical2
ZG20CrMo-SR has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of ZG20CrMo-SR takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 75%.
Manufacturability8
ZG20CrMo-SR's machinability is good (57/100, better than 71% of steel grades); weldability good (64/100); formability not recommended (14/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ZG20CrMo-SR
Is ZG20CrMo easy to machine?
Machine in the annealed or N+T condition with coated carbide, moderate speeds and rigid setups; watch for hard spots and sand inclusions in the cast skin.
Can ZG20CrMo be welded?
Weldable with matching 1.25Cr-0.5Mo/E8018-B2-type consumables using 150–250 °C preheat, low-hydrogen practice and 620–680 °C PWHT to avoid HAZ hardening and cracking.
Can ZG20CrMo be formed, bent or molded?
Sand or investment cast with generous risering and 2–3 % shrink allowance; avoid abrupt section changes and heat-treat after gate removal.
What surface finishes work on ZG20CrMo?
No anodizing; use shot blasting plus epoxy/aluminium-pigment paint, phosphating or metallizing for atmospheric protection, and machine seating faces to seal quality.
ZG20CrMo 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.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | 0.17 – 0.25 | 0.21 |
| Si | 0.2 – 0.6 | 0.4 |
| Mn | 0.5 – 0.8 | 0.65 |
| Cr | 0.5 – 0.8 | 0.65 |
| Mo | 0.4 – 0.6 | 0.5 |
| Niresidual | ≤ 0.3 | — |
| Curesidual | ≤ 0.3 | — |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
ZG20CrMo-SR — frequently asked
What is ZG20CrMo-SR used for?
ZG20CrMo-SR is typically used for valve bodies, pressure vessel castings and pipe fittings. In short: cr-Mo casting for 510 °C; weldable pressure-retaining casting; moderate creep strength.
What is the yield strength of ZG20CrMo-SR?
ZG20CrMo-SR has a typical yield strength of 280 MPa (40.6 ksi) and a tensile strength of 510 MPa (74 ksi) — weaker than 90% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is ZG20CrMo-SR easy to machine?
Reasonably — machinability is rated good (57/100, better than 71% of steel grades). Machine in the annealed or N+T condition with coated carbide, moderate speeds and rigid setups; watch for hard spots and sand inclusions in the cast skin.
Can ZG20CrMo-SR be welded?
Yes — weldability is rated good (64/100). Weldable with matching 1.25Cr-0.5Mo/E8018-B2-type consumables using 150–250 °C preheat, low-hydrogen practice and 620–680 °C PWHT to avoid HAZ hardening and cracking.
What surface finishes work on ZG20CrMo-SR?
No anodizing; use shot blasting plus epoxy/aluminium-pigment paint, phosphating or metallizing for atmospheric protection, and machine seating faces to seal quality.
Can ZG20CrMo-SR be formed, bent or molded?
Sand or investment cast with generous risering and 2–3 % shrink allowance; avoid abrupt section changes and heat-treat after gate removal.
What is the maximum service temperature of ZG20CrMo-SR?
ZG20CrMo-SR is rated for continuous use to about 510°C (950 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ZG20CrMo N+T and ZG20CrMo-QT?
N+T is the default condition — standard delivery condition for pressure-vessel and valve castings; balanced strength, toughness and elevated-temperature stability. QT: pick when higher yield strength and low-temperature toughness are needed in thinner sections, e.g. high-pressure valve bodies. Yield strength is 285 MPa in N+T versus 470 MPa in QT.
Sources
- ASTM A217/A217M (WC1, WC6 Cr-Mo steel castings) — ASTM (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (cast low-alloy steels) — ASM International (1990)
- Mysteel / 1688 (2026)
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.