Steel A897 Grade 5-AT (Austempered to A897 Grade 5)
Precip hard · default condition
ASTM A897 Grade 5 · EN EN-GJS-1400-1 · GB QTA1400-1
Standard as-supplied condition: austenitised ~870–900 °C then austempered near 260 °C to the maximum-hardness ausferrite; pick for extreme abrasion and contact-fatigue duty.
Values for the AT condition
Other A897 Grade 5 tempers and conditions
A897 Grade 5 is listed in 4 conditions; see the grade overview at A897 Grade 5.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As-cast ductile iron blank prior to austempering | The pearlitic/ferritic casting as delivered from the foundry — the state in which rough machining is done before heat treatment; not a service condition for Grade 5. | 450 | 700 | 6 | 22 HRC | 2.9 % IACS |
ATDefaultThis page Austempered to A897 Grade 5 | Standard as-supplied condition: austenitised ~870–900 °C then austempered near 260 °C to the maximum-hardness ausferrite; pick for extreme abrasion and contact-fatigue duty. | 1,200 | 1,500 | 1.5 | 45 HRC | — |
Austempered and shot peened | Choose when fatigue life of gear roots, fillets and springs governs; peening adds compressive residual stress and transforms surface austenite to martensite. | 1,200 | 1,500 | 1.5 | 48 HRC | 2.3 % IACS |
Austempered and fillet/roll burnished | Used on crankshaft fillets and shaft radii where deep rolled compressive stress is required beyond what peening gives. | 1,200 | 1,500 | 1.5 | 47 HRC | 2.3 % IACS |
What is A897 Grade 5-AT?
A897 Grade 5-AT is A897 Grade 5 in the AT condition — standard as-supplied condition: austenitised ~870–900 °C then austempered near 260 °C to the maximum-hardness ausferrite; pick for extreme abrasion and contact-fatigue duty. A897 Grade 5-AT has a yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 94% of steel grades. Elongation at break is 1.5% and the elastic modulus is 168 GPa (24.4 Msi). A897 Grade 5-AT has a density of 7.1 g/cm³ (0.257 lb/in³), lighter than 99% of steel grades. It melts at 1,150°C (2,102 °F).
Advantages
- High strength — 1,200 MPa (174 ksi), better than 94% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
Limitations
- Difficult to weld — 5/100, worse than 100% of steel grades
- Limited ductility — 1.5%, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Low electrical conductivity — 2.3 % IACS, worse than 98% of steel grades
- Difficult to machine — 15/100, worse than 98% of steel grades
A897 Grade 5-AT properties
Typical room-temperature values for A897 Grade 5-AT; 10 are specific to this condition. Other listed values are A897 Grade 5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A897 Grade 5-AT has a density of 7.1 g/cm³ (0.257 lb/in³), lighter than 99% of steel grades. It melts at 1,150°C (2,102 °F).
Mechanical15
A897 Grade 5-AT has a yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 94% of steel grades. Elongation at break is 1.5% and the elastic modulus is 168 GPa (24.4 Msi).
Thermal6
A897 Grade 5-AT is rated for continuous service to 300°C (572 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
A897 Grade 5-AT conducts electricity at 2.3 % IACS, worse than 98% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of A897 Grade 5-AT takes about 22 MJ of energy and emits 1.9 kg of CO₂ — less than 99% of steel grades. Typical recycled content is 75%.
Manufacturability7
A897 Grade 5-AT's machinability is poor (15/100, worse than 98% of steel grades); weldability not recommended (5/100); formability not recommended (5/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A897 Grade 5-AT
Is A897 Grade 5 easy to machine?
Rough-machine in the as-cast state with 0.3–1 mm stock for growth, then finish by grinding or hard-turning with CBN/ceramic at low feed — Grade 5 at 440 HB is essentially a hard-turning job.
Can A897 Grade 5 be welded?
Not weldable in service condition; any arc heat destroys the ausferrite and forms brittle martensite/carbides — join mechanically or weld the blank before austempering and re-treat.
Can A897 Grade 5 be formed, bent or molded?
Green-sand or no-bake ductile iron casting with good nodularity (>85 %) and no carbides; alloy Cu/Ni/Mo to the section size, then austenitise 870–900 °C and austemper in salt at ~250–275 °C.
What surface finishes work on A897 Grade 5?
Paint, phosphate or black-oxide for corrosion; shot peening is the preferred functional finish; avoid high-temperature coating bakes above ~300 °C which decompose retained austenite.
A897 Grade 5 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 |
|---|---|---|
| CASTM A897 does not fix chemistry; typical base ductile iron per A536 | 3.4 – 3.9 | 3.6 |
| Si | 2.2 – 2.8 | 2.5 |
| Mnkept low to avoid segregation at cell boundaries | 0.15 – 0.35 | 0.25 |
| Mgresidual, for nodularisation | 0.03 – 0.06 | 0.04 |
| Cuhardenability addition | 0.4 – 0.9 | 0.7 |
| Niadded for heavier sections | 0 – 2 | 0.8 |
| Moonly for thick sections; excess causes carbides | 0 – 0.3 | 0.15 |
| Pimpurity limit | ≤ 0.04 | 0.02 |
| Simpurity limit | ≤ 0.02 | 0.01 |
| Fe | balance | — |
A897 Grade 5-AT — frequently asked
What is A897 Grade 5-AT used for?
A897 Grade 5-AT is typically used for wear plates, cam followers, railway components and agricultural wear parts. In short: hardest ADI grade; extreme abrasion resistance; minimal ductility, grind to finish.
What is the yield strength of A897 Grade 5-AT?
A897 Grade 5-AT has a typical yield strength of 1,200 MPa (174 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 94% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is A897 Grade 5-AT easy to machine?
Not especially — machinability is rated poor (15/100, worse than 98% of steel grades). Rough-machine in the as-cast state with 0.3–1 mm stock for growth, then finish by grinding or hard-turning with CBN/ceramic at low feed — Grade 5 at 440 HB is essentially a hard-turning job.
Can A897 Grade 5-AT be welded?
Not readily — weldability is rated not recommended (5/100). Not weldable in service condition; any arc heat destroys the ausferrite and forms brittle martensite/carbides — join mechanically or weld the blank before austempering and re-treat.
What surface finishes work on A897 Grade 5-AT?
Paint, phosphate or black-oxide for corrosion; shot peening is the preferred functional finish; avoid high-temperature coating bakes above ~300 °C which decompose retained austenite.
Can A897 Grade 5-AT be formed, bent or molded?
Green-sand or no-bake ductile iron casting with good nodularity (>85 %) and no carbides; alloy Cu/Ni/Mo to the section size, then austenitise 870–900 °C and austemper in salt at ~250–275 °C.
What is the maximum service temperature of A897 Grade 5-AT?
A897 Grade 5-AT is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A897 Grade 5-AT and A897 Grade 5-ASC?
AT is the default condition — standard as-supplied condition: austenitised ~870–900 °C then austempered near 260 °C to the maximum-hardness ausferrite; pick for extreme abrasion and contact-fatigue duty. ASC: the pearlitic/ferritic casting as delivered from the foundry — the state in which rough machining is done before heat treatment; not a service condition for Grade 5. Yield strength is 1,200 MPa in AT versus 450 MPa in ASC.
Sources
- ASTM A897/A897M — Standard Specification for Austempered Ductile Iron Castings — ASTM International (2016)
- EN 1564 — Founding: Ausferritic spheroidal graphite cast irons — CEN (2011)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- Ductile Iron Data for Design Engineers / ADI section — Rio Tinto Iron & Titanium — Ductile Iron Society (1998)
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.