Cast Iron Properties

Mechanical property reference data for various grey cast irons, includes Tensile strength, Compressive Strength, Shear Modulus of Rupture, Tensile Modulus of Elasticity, Torsional Modulus of Elasticity, Endurance Limit and Brinell hardness data.

The American Society for Testing Materials (ASTM) numbering system for grey cast iron is established such that the numbers corespond to the minimum tensile strength in KPSI. Thus an ASTM No. 20 cast iron has a minimum tensile strength of 20 KPSI. Note particularly that the tabulations are typical values. Multiply strength in KPSI by 6.89 to get strength in MPa.

Steels given for comparison purposes. Tensile and hardness given as rolled and heat treated by water quench and tempered at 425°F. The SAE 1050 heat treated is roughly the properties of most anvils. However the temper condition given is softer. Use the SAE 1095 temper for anvils.

IRON	Shear			Modulus of Elasticity
ASTM Number	Tensile strength KPSI	Compressive strength KPSI	modulus of rupture KPSI	MPSI Tension Torsion		Endurance limit KPSI	Brinell Hardness Hb
20	22	83	26	9.6 - 14	3.9 - 5.6	10	156
25	26	97	32	11.5 - 14.8	4.6 - 6.0	11.5	174
30	31	109	40	13.0 - 16.4	5.6 - 6.6	14	201
35	36.5	124	48.5	14.5 - 17.2	5.8 - 6.9	16	212
40	42.5	140	57	16.0 - 20	6.4 - 7.8	18.5	235
50	52.5	164	73	18.8 - 22.8	7.2 - 8.0	21.5	262
60	62.5	187.5	88.5	20.4 - 23.5	7.8 - 8.5	24.5	302
AISI-SAE STEEL	Tensile strength KPSI As rolled Heat treated		Yeild KPSI	MPSI Tension Torsion		Brinell Hardness Hb	Brinell Hardness Hb @ 425°F
1020	65	~100	48 / 80	29.5		143	~300
1050	105	145	60 / 100	30		229	375
1095	140	216	83 / 139	30		293	388

Cast iron is a brittle virtually non-maleable metal that is considered generally inflexible. Cast iron is NOT the metal worked by blacksmiths. It cannot be forged. Cast iron is worked by melting to a liquid and pouring in molds, then by sawing, filing, machining (chip making methods). The stiffness and dampening properties of cast iron make it an excellent material for machine tool frames and parts.

2003 - 2004 Jock Dempsey, www.anvilfire.com