What is the difference between IS 1367 Gr. 4.6, 8.8 & 10.9?

IS 1367 is a standard for bolts and Gr. 4.6, 8.8 & 10.9 are fastener grades as per the said standard Grade 8.8 means, Approx. 800...

IS 1367 is a standard for bolts and Gr. 4.6, 8.8 & 10.9 are fastener grades as per the said standard

Grade 8.8 means, Approx. 800 Mpa. tensile strength and 640 Mpa. yield strength (you will arrive at the yield strength by multiplying both the numbers times 10. That is 8x8x10=640)

Similarly, 10.9 means approx.1000Mpa tensile strength and 900 Mpa. yield strength. See the below table for details.

Property Class	Tensile strength, Mpa	Hardness	Material	Heat Treatment	Tempering
4.6	400	B67-B87	low or medium carbon steel with max limits for C 0.55, P0.048, S0.058	No	-
4.8	420	B71-B87
5.8	520	B82-B95
8.8	830	C23-C34	medium carbon steel with max limits for C0.28- 0.55, P0.048, S0.058	Oil Quenched	Min. 425°C
9.8	900	C27-C36			Min. 410°C
10.9	1040	C33-C39			Min. 425°C
12.9	1220	C38-C44	medium carbon steel with max limits for C0.31- 0.65, P 0.045 MAX, S 0.045MAX	Oil Quenched	Min. 380°C