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Bolts grade, strength distinction and tightening
Strength to distinguish		4.8	5.6	6.8	7.6	8.8	10.9	12.9
Minimum breaking strength		40kg/mm2	50kg/mm2	60kg/mm2	70kg/mm2	800kg/mm2	100kg/mm2	120kg/mm2
The material		45#	35#	40chromium	Alloy steel (hot)	Chromium-molybdenum alloy steel (hot)	Ni-cr-mo alloy steel (hot)	Ni-cr-mo alloy steel (hot)
			（hot）	（hot）
Bolt	Nut Smm	kgm	kgm	Kgm	kgm	kgm	kgm	kgm
M8	12.5	2.4	2.9	3.43	3.77	9.8	6.34	7.89
M10	15.4	3.43	4.16	4.9	5.39	6.86	9.06	11.27
M12	17.3	4.9	5.95	7	7.7	4.8	12.95	16.1
M14	22	7	8.5	10	11	14	18.5	23
M16	24	10	12	14	17.5	21	28.5	36
M18	27	14	17.5	21	25	29	39	49
M20	30	18	23	28	34.5	41	55	69
M22	32	23	28.5	34	44.5	55	74	93
M24	36	32	40	48	59	70	95	120
M27	41	45	55	65	85	105	142.5	180
M30	46	60	75	90	105	120	180	240
M36	55	100	125	150	165	180	240	300
M42	65	155	197.5	240	260	280	375	470
M48	75	230	197.5	350	375	400	540	680
M52	80	280	350	420	450	480	665	850
M56	85	360	495	530	570	610	830	1050
M60	90	410	510	610	700	790	1070	1350
M64	95	510	635	760	830	900	1170	1521
M72	105	660	830	1000	1145	1290
M76	110	750	925	1100	1300	1500	2045
M80	115	830	1040	1250	1550	1850
M90	130	1080	1365	1650	2075	2500
M100	145	1400	1725	2050
M110	155	1670	2110	2550	4980
M120	175	2030	2540	3050
M140	200	2700	3375	4050
Note: The torque value in the table is the maximum torque value. It is recommended that the tightening torque value be the value in the table x 70-80%
Example: m48 bolt grade 8.8 table lookup 400× 80% = 320kgm
Nuts used are reduced by one grade. Example: grade 8.8 for bolts and nuts, grade 7.6
The commonly used bolt strength is 8.8, for example, according to the 8.8 standard, when the bolt strength is 5.6, the value of 8.8 in the table is 0.47, when the bolt strength is 10.9, multiplied by 1.41, when the bolt strength is 12.9, the value should be multiplied by 1.69 (then the column 8.8 can be recorded).