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Cast Iron and Steel Casting Grades: ASTM Reference Table

Buyers, foundry engineers and ERP item master owners keep asking the same question: what does Class 30 or 65-45-12 actually guarantee? This table lists the common ASTM casting grades with minimum tensile strength in ksi and MPa, so you can check a drawing callout or a purchase order line quickly.

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Standard	Grade / class	Material family	Min tensile (ksi)	Min tensile (MPa)	Min yield	Note
ASTM A48	Class 20	Gray iron	20	138	Not specified	Separately cast test bar
ASTM A48	Class 25	Gray iron	25	172	Not specified	Common general purpose grade
ASTM A48	Class 30	Gray iron	30	207	Not specified	Common for housings and brake parts
ASTM A48	Class 35	Gray iron	35	241	Not specified	Higher strength, more alloying or inoculation
ASTM A48	Class 40	Gray iron	40	276	Not specified	Machine tool and engine castings
ASTM A48	Class 45	Gray iron	45	310	Not specified	High strength gray iron
ASTM A48	Class 50	Gray iron	50	345	Not specified	High strength gray iron
ASTM A48	Class 60	Gray iron	60	414	Not specified	Highest A48 class, section sensitive
ASTM A536	60-40-18	Ductile iron	60	414	40 ksi	Ferritic, 18 percent min elongation
ASTM A536	65-45-12	Ductile iron	65	448	45 ksi	Most common ductile iron grade
ASTM A536	80-55-06	Ductile iron	80	552	55 ksi	Ferritic-pearlitic
ASTM A536	100-70-03	Ductile iron	100	690	70 ksi	Pearlitic or heat treated
ASTM A536	120-90-02	Ductile iron	120	827	90 ksi	Quenched and tempered
ASTM A897/A897M	Grade 1 (850-550-10)	Austempered ductile iron	123	850	550 MPa	Metric grade designation
ASTM A897/A897M	Grade 2 (1050-700-7)	Austempered ductile iron	152	1050	700 MPa	Gears, crankshafts
ASTM A897/A897M	Grade 3 (1200-850-4)	Austempered ductile iron	174	1200	850 MPa	High wear applications
ASTM A27/A27M	60-30	Carbon steel casting	60	415	30 ksi	General application
ASTM A27/A27M	65-35	Carbon steel casting	65	450	35 ksi	General application
ASTM A27/A27M	70-36	Carbon steel casting	70	485	36 ksi	General application
ASTM A27/A27M	70-40	Carbon steel casting	70	485	40 ksi	General application
ASTM A216/A216M	WCA	Carbon steel, pressure	60	415	30 ksi	Valves and fittings, high temperature service
ASTM A216/A216M	WCB	Carbon steel, pressure	70	485	36 ksi	Most common valve body grade
ASTM A216/A216M	WCC	Carbon steel, pressure	70	485	40 ksi	Valves and fittings
ASTM A351/A351M	CF8	Austenitic stainless casting	70	485	30 ksi	Cast equivalent of 304
ASTM A351/A351M	CF8M	Austenitic stainless casting	70	485	30 ksi	Cast equivalent of 316
ASTM A148/A148M	80-50	High strength steel casting	80	550	50 ksi	Structural applications
ASTM A148/A148M	90-60	High strength steel casting	90	620	60 ksi	Structural applications

Values are the minimum tensile and yield figures commonly quoted from each specification. Always confirm against the current edition of the standard and your purchase order, since test bar type, section size and supplementary requirements change what is actually certified.

Material grade cleanup for your item master

Optional: send us an export of your casting item descriptions and we will return a mapping of free text to controlled grade strings.

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How to use the table

Type a grade, a standard number or a material family into the search box to filter the rows. Each row gives the specification, grade name, minimum tensile strength in both unit systems, minimum yield where the standard defines one, and a short note on typical use. Use the Excel export to paste the grades into an item master, a supplier quality agreement or a material approval list. Gray iron grades under A48 are classified by tensile strength alone, so yield is shown as not specified.

Search by standard to see every grade in one specification
Sort mentally by tensile column to compare strength steps
Export to Excel for approved material lists
Check the note column for typical applications

Reading grade names

Ductile iron grades under A536 use three numbers: minimum tensile in ksi, minimum yield in ksi, then minimum elongation in percent. So 65-45-12 means 65 ksi tensile, 45 ksi yield and 12 percent elongation. Gray iron A48 uses a class number that equals the minimum tensile strength in ksi. Austempered ductile iron under A897M uses metric values in MPa, for example 850-550-10. Pressure steel castings under A216 use letter grades such as WCB instead, and the strength is found in the specification tables.

A48 Class 30 equals 30 ksi minimum tensile
A536 65-45-12 equals tensile, yield, elongation
A897M grades are in MPa, not ksi
A216 WCB is the common valve body grade

Common mistakes

The biggest mistake is treating a minimum value from a separately cast test bar as the strength of every location in a real casting. Section thickness, cooling rate and feeding all change local properties, especially in gray iron. The second mistake is mixing metric and imperial designations on one purchase order, for example calling out a ductile grade by ksi while the supplier certifies in MPa. Third, buyers sometimes assume an equivalent grade from another standard such as EN or ISO is interchangeable. Confirm equivalence with the foundry and the design engineer.

Do not assume bar strength equals casting strength
State the standard edition on the PO
Do not treat cross-standard grades as equal without review

Using grades in an ERP

Most ERPs store the casting material as a free text attribute or a classification code on the item. Pick one convention, for example the standard plus grade as in ASTM A536 65-45-12, and enforce it so that supplier certificates, receiving inspection plans and cost roll-ups all point to the same string. In SAP this fits a class and characteristic, in Infor SyteLine a user defined field or item attribute, and in Epicor a part attribute or UD field.

Frequently Asked Questions

What does ASTM A48 Class 30 mean?

It is a gray iron class with a minimum tensile strength of 30 ksi, about 207 MPa, measured on a separately cast test bar. The class number is the minimum tensile strength in ksi. Hardness and the strength in the actual casting vary with section size.

What do the three numbers in 65-45-12 mean?

For ductile iron under ASTM A536 they are minimum tensile strength in ksi, minimum yield strength in ksi and minimum elongation in percent. So 65-45-12 is 65 ksi tensile, 45 ksi yield and 12 percent elongation.

Is WCB the same as A216 Grade WCB cast steel?

Yes. WCB is a grade name within ASTM A216 for carbon steel castings used in pressure containing parts such as valve bodies. It requires 70 ksi minimum tensile and 36 ksi minimum yield, with chemistry and heat treatment set by the standard.

Are these values guaranteed for every part?

No. They are minimums from the specification, normally verified on test coupons from the same heat. Local properties in a real casting depend on section thickness, solidification and heat treatment, so critical parts need agreed sampling or cast-on test coupons.

If your item master has inconsistent casting material descriptions, we can help build a cleanup that maps free text to a controlled grade list and checks it against supplier certificates. This tool works fully without contacting us.

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