Stainless Steel ZG40Cr25Ni20Si2
ASTM HK
ZG40Cr25Ni20Si2 is a high-silicon 25Cr-20Ni heat-resistant cast austenitic stainless steel equivalent to ASTM Grade HK.
Reference datasheet — ZG40Cr25Ni20Si2 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the F condition
ZG40Cr25Ni20Si2 tempers and conditions
ZG40Cr25Ni20Si2 is supplied in 3 conditions, soft to hard. F is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed ~1050–1100 °C, rapid cool | Occasionally specified to homogenise the carbide network, relieve casting stresses and slightly improve room-temperature ductility before machining. | 240 | 470 | 15 | 180 HB | 1.9 % IACS |
FDefault As fabricated | Standard supply condition for furnace fixtures, rolls, trays and radiant-tube parts — used directly with no heat treatment. | 250 | 480 | 10 | 190 HB | 1.9 % IACS |
Service-aged / thermally exposed | Reference condition for remaining-life and repair assessment of tubes and fixtures after thousands of hours in service — hardened and strongly embrittled at room temperature. | 300 | 450 | 3 | 20 HRC | 2.1 % IACS |
Supply forms, finishes and certifications
Ways ZG40Cr25Ni20Si2 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
CC | Centrifugally cast | Surface finish |
What is ZG40Cr25Ni20Si2?
ZG40Cr25Ni20Si2 is a high-silicon 25Cr-20Ni heat-resistant cast austenitic stainless steel equivalent to ASTM Grade HK. It is used for furnace and reformer hardware because the Cr₂O₃/SiO₂ scale that forms in service resists oxidation up to 1100 °C; parts are produced by sand, investment and centrifugal casting and supplied as F, CC, SA or aged. Typical properties are 250 MPa yield, 480 MPa tensile, 10 % elongation and 190 HB. Ductility falls further after service aging, machining is difficult and welding of aged parts is crack sensitive; HH (25Cr-12Ni) is the lower-nickel alternative for less severe temperatures. ZG40Cr25Ni20Si2 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,350°C (2,462 °F). ZG40Cr25Ni20Si2 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 10% and the elastic modulus is 185 GPa (26.8 Msi).
What is ZG40Cr25Ni20Si2 used for?
- furnace fixtures
- radiant tube supports
- petrochemical reformer castings
- kiln components
Advantages
- High service temperature — 1,100°C (2,012 °F), better than 96% of stainless steel grades
Limitations
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Limited ductility — 10%, worse than 98% of stainless steel grades
- Hard to polish — 50/100, worse than 93% of stainless steel grades
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 92% of stainless steel grades
- Low strength — 250 MPa (36.3 ksi), worse than 91% of stainless steel grades
ZG40Cr25Ni20Si2 properties
Typical room-temperature values for ZG40Cr25Ni20Si2-F; bars are the position among stainless steel grades.
Physical3
ZG40Cr25Ni20Si2 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,350°C (2,462 °F).
Mechanical14
ZG40Cr25Ni20Si2 has a yield strength of 250 MPa (36.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 91% of stainless steel grades. Elongation at break is 10% and the elastic modulus is 185 GPa (26.8 Msi).
Thermal6
ZG40Cr25Ni20Si2 is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 13.5 W/m·K (7.8 BTU/hr·ft·°F), worse than 83% of stainless steel grades. Thermal expansion is 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
ZG40Cr25Ni20Si2 conducts electricity at 1.9 % IACS, worse than 84% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (62/100), worse than 52% of stainless steel grades.
Sustainability4
Producing a kilogram of ZG40Cr25Ni20Si2 takes about 58 MJ of energy and emits 4.6 kg of CO₂ — more than 66% of stainless steel grades. Typical recycled content is 60%.
Manufacturability7
ZG40Cr25Ni20Si2's machinability is poor (25/100, worse than 88% of stainless steel grades); weldability fair (40/100); formability not recommended (5/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. ZG40Cr25Ni20Si2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with ZG40Cr25Ni20Si2
Is ZG40Cr25Ni20Si2 easy to machine?
Difficult: hard interdendritic carbides and work hardening — use rigid setups, carbide or ceramic inserts, low speed/heavy positive feed, flood coolant, and avoid dwelling.
Can ZG40Cr25Ni20Si2 be welded?
Weld with matching 25Cr-20Ni (ER310/HK) filler, low heat input and interpass control; hot-crack and post-service embrittlement risk means aged parts often need buttering or carbide-removal grinding first.
Can ZG40Cr25Ni20Si2 be formed, bent or molded?
Casting-only grade — sand, investment and centrifugal routes are all standard; provide generous risers because of the wide freezing range and ~2 % shrinkage.
ZG40Cr25Ni20Si2 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 |
|---|---|---|
| Chigh C gives creep strength via carbide network | 0.3 – 0.5 | 0.4 |
| Siboosts scaling resistance | 1 – 2.5 | 1.8 |
| Mn | ≤ 2 | 1 |
| P | ≤ 0.04 | |
| S | ≤ 0.03 | |
| Cr | 24 – 27 | 25.5 |
| Ni | 19 – 22 | 20.5 |
| Moresidual, restricted in some specs | ≤ 0.5 | |
| Fe | balance |
What surface finishes work on ZG40Cr25Ni20Si2?
Shot blast or pickle to remove scale; passivation improves aqueous corrosion resistance; no coating normally used, service-formed Cr₂O₃/SiO₂ scale is the protective layer.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel ZG40Cr25Ni20Si2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- HK
How much does ZG40Cr25Ni20Si2 cost?
ZG40Cr25Ni20Si2 is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
ZG40Cr25Ni20Si2 — frequently asked
What is ZG40Cr25Ni20Si2 used for?
ZG40Cr25Ni20Si2 is typically used for furnace fixtures, radiant tube supports, petrochemical reformer castings and kiln components. In short: ASTM HK equivalent; 1100 °C service ceiling; cast-only heat-resistant grade.
What is the yield strength of ZG40Cr25Ni20Si2?
ZG40Cr25Ni20Si2 has a typical yield strength of 250 MPa (36.3 ksi) and a tensile strength of 480 MPa (69.6 ksi) — weaker than 91% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is ZG40Cr25Ni20Si2 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 88% of stainless steel grades). Difficult: hard interdendritic carbides and work hardening — use rigid setups, carbide or ceramic inserts, low speed/heavy positive feed, flood coolant, and avoid dwelling.
Can ZG40Cr25Ni20Si2 be welded?
With care — weldability is rated fair (40/100). Weld with matching 25Cr-20Ni (ER310/HK) filler, low heat input and interpass control; hot-crack and post-service embrittlement risk means aged parts often need buttering or carbide-removal grinding first.
What surface finishes work on ZG40Cr25Ni20Si2?
Shot blast or pickle to remove scale; passivation improves aqueous corrosion resistance; no coating normally used, service-formed Cr₂O₃/SiO₂ scale is the protective layer.
Can ZG40Cr25Ni20Si2 be formed, bent or molded?
Casting-only grade — sand, investment and centrifugal routes are all standard; provide generous risers because of the wide freezing range and ~2 % shrinkage.
What is the maximum service temperature of ZG40Cr25Ni20Si2?
ZG40Cr25Ni20Si2 is rated for continuous use to about 1,100°C (2,012 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ZG40Cr25Ni20Si2-F and ZG40Cr25Ni20Si2 Aged?
F is the default condition — standard supply condition for furnace fixtures, rolls, trays and radiant-tube parts — used directly with no heat treatment. Aged: reference condition for remaining-life and repair assessment of tubes and fixtures after thousands of hours in service — hardened and strongly embrittled at room temperature. Yield strength is 250 MPa in F versus 300 MPa in Aged.
How much does ZG40Cr25Ni20Si2 cost?
ZG40Cr25Ni20Si2 is a premium-cost stainless steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A297/A297M Steel Castings, Iron-Chromium and Iron-Chromium-Nickel, Heat Resistant (HK) — ASTM (2019)
- ASM Handbook Vol.1 — Heat-Resistant Cast Steels — ASM International (1990)
- ASM Handbook Vol.13 — Corrosion: High-Temperature Oxidation — ASM International (2005)
- SFSA Steel Castings Handbook — heat resistant alloys — Steel Founders' Society of America (2004)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.