Drawing:

Hexagon head bolts-Full thread--Product grades A and B
ISO4017 & GB/T5783
d	P(mm)	k(mm)				s(mm)
		A		B		min		max
		min	max	min	max	A	B
M1.6	0.35	0.975	1.225	0.9	1.3	3.02	2.9	3.2
M2	0.4	1.275	1.525	1.2	1.6	3.82	3.7	4
M2.5	0.45	1.575	1.825	1.5	1.9	4.82	4.7	5
M3	0.5	1.875	2.125	1.8	2.2	5.32	5.2	5.5
M3.5	0.6	2.275	2.525	2.2	2.6	5.82	5.7	6
M4	0.7	2.675	2.925	2.6	3	6.78	6.64	7
M5	0.8	3.35	3.65	3.26	3.74	7.78	7.64	8
M6	1	3.85	4.15	3.76	4.24	9.78	9.64	10
M8	1.25	5.15	5.45	5.06	5.54	12.73	12.57	13
M10	1.5	6.22	6.58	6.11	6.69	15.73	15.57	16
M12	1.75	7.32	7.68	7.21	7.79	17.73	17.57	18
M14	2	8.62	8.98	8.51	9.09	20.67	20.16	21
M16	2	9.82	10.18	9.71	10.29	23.67	23.16	24
M18	2.5	11.29	11.72	11.15	11.85	26.67	26.16	27
M20	2.5	12.29	12.72	12.15	12.85	29.67	29.16	30
M22	2.5	13.79	14.22	13.65	14.35	33.38	33	34
M24	3	14.79	15.22	14.65	15.35	35.38	35	36
M27	3	/	/	16.65	17.35	/	40	41
M30	3.5	/	/	18.28	19.12	/	45	46
M33	3.5	/	/	20.58	21.42	/	49	50
M36	4	/	/	22.08	22.92	/	53.8	55
M39	4	/	/	24.58	25.42	/	58.8	60
M42	4.5	/	/	25.58	26.42	/	63.1	65
M45	4.5	/	/	27.58	28.42	/	68.1	70
M48	5	/	/	29.58	30.42	/	73.1	75
M52	5	/	/	32.5	33.5	/	78.1	80
M56	5.5	/	/	34.5	35.5	/	82.8	85
M60	5.5	/	/	37.5	38.5	/	87.8	90
M64	6	/	/	39.5	40.5	/	92.8	95

About the Hex bolts:

Hex cap screws and hex bolts feature a hexagonal head that is utilized during the tightening of the fastener.

A hex cap screw utilizes a washer face under the head and a chamfered end,while the hex bolts lack those features and requires a nut.

Hex cap screws and hex bolts are manufactured in variety of sizes,finishes,grades,and materials depending on application.

The function of hot dip galvanizing:

Hot-dip galvanizing prevents corrosion by offering barrier and galvanic protection to the base steel. The galvanized coating is metallurgically bonded to the underlying steel, forming an impervious barrier between the steel substrate and the corrosive environment. The hot-dip galvanized coating also preferentially corrodes to protect the underlying steel and is able to protect small areas of steel that may become exposed when scratched or abraded. Hot-dip galvanizing is the most effective method for delivering long-term barrier and cathodic protection.

Applications:

These fasteners are commonly used in construction,machine parts,and maintenance repairs.