30CND8 Alloy Steel | 30CrNiMo8

AS a low alloy high strength steel,30CND8 steel contains 2% Cr and 2% Ni elements as strengthening alloy elements as per French Standard NF A35-556.

30CND8 steel has high yield strength, tensile strength and fatigue strength, as well as sufficient plasticity and toughness after quenched and tempered condition.

Due to its excellent comprehensive performance, 30CND8 is often used in the production of high-end mechanical parts, such as screws, robotic arms, pistons, shafts, etc. In addition, 30CND8 steel is also used in occasions where product wear is high. The excellent corrosion resistance of 30CND8 steel makes it a very useful material in the oil and gas industry, aviation, mechanical engineering, chemical industry and shipbuilding.

WHAT IS 30CND8 STEEL?

NF is the standard code for Norms Francaises, which is formulated by the French Association for Standardization (AFNOR). Next, we will introduce the representation method of alloy steel under the NF standard.

XX OOO XX

1.XX represents the carbon content, expressed as C%x100.

2.OOO stands for alloying element symbol, the specific meaning is shown in Table 1 below

3.XX represents the content of each alloy element, which is expressed by multiplying the actual average content percentage of the main element by the index of the element listed in Table 1.

Table 1
Alloy element	Symbol	Index	Alloy element	Symbol	Index
Cr	C	4	Sn	E	10
Co	K	4	Mg	G	10
Mn	M	4	Mo	D	10
Ni	N	4	P	P	10
Si	S	4	Pb	Pb	10
Al	A	10	W	W	10
Be	Be	10	V	V	10
Cu	U	10	Zn	Z	10

Remark:

If the content of the main alloying elements in the steel is lower than the following conditions, it is not necessary to indicate the steel grade.

Mn and Si < 1.2%
Ni <0.2%
Cr <0.25%
Mo<0.1%
V<0.05%

From the above content, we can easily know that in 30CND8 steel, 30 means the average carbon content is 0.30%, the average content of Cr and Ni elements is 8/4=2%, and it contains not less than 0.1% Mo element ( Actual: 0.3-0.5%)

30CND8 STEEL CHEMICAL COMPOSITION

Grade	C	Si	Mn	P	S	Cr	Ni	Mo
30CND8	0.26-0.33	0.1-0.4	0.30-0.60	≤0.03	≤0.025	1.8-2.2	1.8-2.2	0.3-0.5

30CND8 STEEL RELATED STANDARD & EQUIVALENT GRADE

CHINA | GB 3077:30Cr2Ni2Mo

Europe | EN10083:30CrNiMo8

UK | BS970:823M30

30CND8 STEEL FORGING

Initial Forging Temperature：1180-1220℃
Final Forging Temperature：800℃
Heating Rate:Strictly control the heating speed, which should be uniform and stable to prevent cracking caused by improper heating.
Forging Ratio：above 4:1
Post-Forging Treatment:30CND8 steel is highly sensitive to white point,and it needs to be dehydrogenated at a temperature of 630-660℃ immediately after forging.

30CND8 STEEL HEAT TREATMENT

Critical Temperature for Heat Treatment of 30CND8 Steel

Ac1:740℃
Ac3:810℃
Ms:320℃

Temperature Selection for Conventional Heat treatment for 30CND8 Steel

Soft Annealing:650 – 690°C,Cooling in furnace,hardness below 248 HBW
Normalizing:850-900°C
Oil Quenching:830-860°C
Tempering:530-630°C

30CND8 Steel Mechanical Property at 20^oC for Forged parts in Quenched & Tempered condition

Diameter mm	≤250	250-500	500-1000
Tensile Strength Mpa	880-1080	830-980	780-930
Yield Strength Mpa	≥685	≥635	≥590
Elongation %	L:≥12 T:≥10	L:≥12 T:≥10	L:≥12 T:≥10
Impact Charpy J	L:≥45 T:≥34	L:≥45 T:≥34	L:≥45 T:≥34

30CND8 Steel 0.2% Yield Strength vs Different High Temperature in Quenched & Tempered condition

	0.2% Yield Strength or Yield Point Mpa,Min
Diameter mm	20℃	100℃	200℃	250℃	300℃	350℃	400℃
≤250	≥685	≥657	≥628	≥598	≥559	≥520	≥481
250-500	≥635	≥608	≥579	≥549	≥510	≥471	≥431
500-1000	≥590	≥559	≥530	≥500	≥471	≥431	≥392

Jominy Quenching Test Curve For 30CND8 Steel

Jominy Quenching Test Curve For 30CND8 Steel

Quenching at 850°C

X:Distance from quenched end,in mm

Y:Hardness,HRC

1: HH level

2: HL level

3: H level

HRC-mm	Type	1.5	3	6	7	9	11	13	15	20	25	30	35	40	45	50
MIN	+H	48	48	48	48	47	47	47	46	46	45	45	44	44	43	43
MAX	+H	56	56	56	56	55	55	55	55	55	54	54	54	54	54	54
MIN	+HH	51	51	51	51	50	50	50	49	49	48	48	47	47	47	47
MAX	+HH	56	56	56	56	55	55	55	55	55	54	54	54	54	54	54
MIN	+HL	48	48	48	48	47	47	47	46	46	45	45	44	44	43	43
MAX	+HL	53	53	53	53	52	52	52	52	52	51	51	51	51	50	50