Grey Cast Iron Composition and Property

Grey Cast Iron (Gray iron) is so called because of the color of the fracture face. It contains 1.5-4.3% carbon and 0.3-5% silicon plus manganese, sulphur and phosphorus. It is brittle with low tensile strength, but is easy to cast.

The all data in this document is referred to Chinese standard of GB/T 9439-1988.

Single Casting Specimen Tensile Strength Property

Gray iron grade	Single specimen Tensile Strength σb≥/Mpa	Gray iron castings
Gray iron grade	Single specimen Tensile Strength σb≥/Mpa	Wall thickness/mm	Tensile strength σb≥/Mpa
HT100	100	>2.5~10 >10~20 >20~30 >30~40	130 100 90 80
HT150	150	>2.5~10 >10~20 >20~30 >30~40	175 145 130 120
HT200	200	>2.5~10 >10~20 >20~30 >30~40	220 195 170 160
HT250	250	>4.0~10 >10~20 >20~30 >30~50	270 240 220 200
HT300	300	>10~20 >20~30 >30~50	290 250 230
HT350	350	>10~20 >20~30 >30~50	340 290 260

Castings Attached Specimen Tensile Strength Property

Gray iron grad	Wall thickness /mm	Tensile strength σb≥/Mpa				Tensile strength (reference) σb≥/Mpa
		Attached test coupon		Attached test block
		φ30mm	φ50mm	R15mm	R25mm
HT150	>20~40 >40~80 >80~150 >150~300	130 115 - -	- (115) 105 100	120 110 - -	- - 100 90	120 105 90 80
HT200	>20~40 >40~80 >80~150 >150~300	180 160 - -	- (155) 145 135	170 150 - -	- - 140 130	165 145 130 120
HT250	>20~40 >40~80 >80~150 >150~300	220 200 - -	- (190) 180 165	(210) 190 - -	- - 170 160	205 180 165 150
HT300	>20~40 >40~80 >80~150 >150~300	260 235 - -	- (230) 210 195	(250) 225 - -	- - 200 185	245 215 195 180
HT350	>20~40 >40~80 >80~150 >150~300	300 270 - -	- (265) 240 215	(290) 260 - -	- - 230 210	285 255 225 205

Grey Iron Castings’ other mechanical property

Grade	Compressive Strength σbc/MPa	Shearing Strength τb/Mpa	Impact Testing αKV/(J/cm2)	Safe Range of stress σ-1/MPa	Modulus of Elasticity Ε/GPa
HT150	500~700	150~250	-	60~90	70~90
HT200	600~800	200~300	2~5	80~90	80~110
HT250	800~1000	250~350	4~8	100~140	100~130
HT300	1000~1200	300~450	7~10	120~160	120~140
HT350	1100~1300	350~500	9~11	140~180	130~160

Grey Iron Castings Hardness

Grey iron grade	Hardness grade	Hardness Range HBS	Metallography
HT100	H145	≤170	Ferrite
HT150	H175	150~200	Ferrite + Pearlite
HT200	H195	170~220	Pearlite
HT250	H215	190~240	Pearlite
HT300	H235	210~260	Pearlite(Inoculated Cast Iron)
HT350	H255	230~280	Pearlite(Inoculated Cast Iron)

Gray Iron Casting heat treatment

Casting Unit Weight kg	Starting Temperature /οC	Heating Speed /(οC/h)	Preservation temperature		Heat Preservation Time /h	Cooling Speed /(οC/h)	Final Temperature /οC
Casting Unit Weight kg	Starting Temperature /οC	Heating Speed /(οC/h)	Cast iron	Low alloy cast iron	Heat Preservation Time /h	Cooling Speed /(οC/h)	Final Temperature /οC
Simple castings
<200	≤200	≤100	500~550	550~570	4~6	30	200
200~2500	≤200	≤80	500~550	550~570	6~8	30	200
>2500	≤200	≤60	500~550	550~570	8	30	200
Precision Castings
<200	≤200	≤100	500~550	550~570	4~6	20	200
200~2500	≤200	≤80	500~550	550~570	6~8	20	200

Gray Iron Casting, no any standard mentioned the chemistry composition, so we only suggest the following chemistry based on actual production.

Grade	Wall Thickness /mm	C	Si	Mn	P ≤	S ≤
HT100	-	3.4~3.9	2.1~2.6	0.5~0.8	0.3	0.15
HT150	<30 30~50 >50	3.3~3.5 3.2~3.5 3.2~3.5	2.0~2.4 1.9~2.3 1.8~2.2	0.5~0.8 0.5~0.8 0.6~0.9	0.2 0.2 0.2	0.12 0.12 0.12
HT200	<30 30~50 >50	3.2~3.5 3.1~3.4 3.0~3.3	1.6~2.0 1.5~1.8 1.4~1.6	1.7~0.9 0.8~1.0 0.8~1.0	0.15 0.15 0.15	0.12 0.12 0.12
HT250	<30 30~50 >50	3.0~3.3 2.9~3.2 2.8~3.1	1.4~1.7 1.3~1.6 1.2~1.5	0.8~1.0 0.9~1.1 1.0~1.2	0.15 0.15 0.15	0.12 0.12 0.12
HT300	<30 30~50 >50	2.9~3.2 2.9~3.2 2.8~3.1	1.4~1.7 1.2~1.5 1.1~1.4	0.8~1.0 0.9~1.1 1.0~1.2	0.15 0.15 0.15	0.10 0.10 0.10

Grey Cast Iron Compare

Index	County	Grey iron grade
1	China	-	HT350	HT300	HT250	HT200	HT150	HT100
2	Japanese	-	FC350	FC300	FC250	FC200	FC150	FC100
3	USA	NO.60	NO.50	NO.45	NO.35/NO.40	NO.30	NO.25	NO.20
4	Russia	CЧ40	CЧ35	CЧ30	CЧ34/ CЧ25	CЧ18/ CЧ20/ CЧ21	CЧ15	CЧ10
5	Germany	GG40	GG35	GG30	GG25	GG20	GG15	GG10
6	Italy	-	G35	G30	G25	G20	G15	G10
7	France	HGL400	FGL350	FGL300	FGL250	FGL200	FGL150	-
8	England	400	350	300	260	180/220	150	100
9	Poland	Z140	Z135	Z130	Z125	Z120	Z115	-
10	India	FG400	FG350	FG300	FG260	FG200	FG150	-
11	Romania	FC400	FC350	FC300	FC250	FC200	FC150	-
12	Spanish	-	FG35	FG30	FG25	FG20	FG15	-
13	Belgium	FGG40	FGG35	FGG30	FGG25	FGG20	FGG15	FGG10
14	Australia	T400	T350	T300	T260	T220	T150	-
15	Sweden	O140	O135	O130	O125	O120	O115	O110
16	Hungary	OV40	OV35	OV30	OV25	OV20	OV15	-
17	Bulgaria	-	Vch35	Vch30	Vch25	Vch20	Vch15	-
18	ISO	-	350	300	250	200	150	100
19	COPANT	FG400	FG350	FG300	FG250	FG200	FG150	FG100
20	Taiwan (China)	-	-	FC300	FC250	FC200	FC150	FC100
21	Holland	-	GG35	GG30	GG25	GG20	GG15	-
22	Luxemburg	FGG40	FGG35	FGG30	FGG25	FGG20	FGG15	-
23	Austria	-	GG35	GG30	GG25	GG20	GG15
24	Europa-Norm		EN-GJL-350	EN-GJL-300	EN-GJL-250	EN-GJL-200	EN-GJL-150

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