DIN931-933 Class 4.8 and 6.8 and 8.8 and 10.9 and 12.9 Hexagon Head Bolts_Natural Gas_Energy_Products

ISO 898-1 Specification

This part of ISO 898 specifies mechanical and physical properties of bolts, screws and studs made of carbon steel and alloy steel when tested at an ambient temperature range of 10 °C to 35 °C. Fasteners — the term used when bolts, screws and studs are considered all together — that conform to the requirements of this part of ISO 898 are evaluated at that ambient temperature range. They might not retain the specified mechanical and physical properties at elevated temperatures (see Annex B) and/or lower temperatures.

ISO 898-1 Chemical Composition

Property class	Material and heat treatment	Chemical composition limits (cast analysis, %) a					Tempering temperature ·c nin.
		c		p max.	s max.	a • max.
		min.	max.	p max.	s max.	a • max.
4.6 c, d	Carbon steel or carbon steelwith additives	-	055	0.050	0,060	Not specified	-
4.8 d		-	055	0.050	0,060
5.6 c		013	055	0.050	0,060
5.8 d		-	055	0.050	0,060
6.8 d		015	055	0.050	0,060
8.8 f	Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered	015.	040	0.025	0,025	0,003	425
	or Carbon steel quenched and tempered	025	055	0.025	0,025
	or Anoy steelquenched and tempered 9	020	055	0.025	0,025
9.8 f	Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered	015.	040	0,025	0,025	0,003	425
	or Carbon steel quenched and tempered	025	055	0.025	0,025
	or Alloy steelquenched and tempered 9	020	055	0.025	0,025
10.9 f	Carbon steel with additives (e.g. Boron or Mn or Cr) quenched and tempered	0,20 .	055	0,025	0,025	0,003	425
	or Carbon steel quenched and tempered	025	055	0.025	0,025
	or Alloy steel quenched and tempered 9	020	055	0,025	0,025
12..9 f.h.i	Alloy steel quenched and tempered 9	030	050	0.025	0,025	0,003	425
12..9 f.h.i	Carbon steel with additives (e.g. Boron or Mn or Cr or Molybdenum)quenched and tempered	028	050	0.025	0,025	0,003	380

Note:
a. In case of dispute, the product analysis applies.
b. Boron content can reach 0,005 %, provided that non-effective boron is controlled by addition of titanium and/or aluminium.
c. For cold forged fasteners of property classes 4.6 and 5.6, heat treatment of the wire used for cold forging or of the cold forged fastener itself may be necessary to achieve required ductility.
d. Free cutting steel is allowed for these property classes with the following maximum sulphur, phosphorus and lead contents: sulphur 0,34 %; phosphorus 0,11 %; lead 0,35 %.
e. In case of plain carbon boron steel with a carbon content below 0,25 % (cast analysis), the minimum manganese content shall be 0,6 % for property class 8.8 and 0,7 % for 9.8 and 10.9.
f. For the materials of these property classes, there shall be a sufficient hardenability to ensure a structure consisting of approximately 90 % martensite in the core of the threaded sections for the fasteners in the “as-hardened” condition before tempering.
g. This alloy steel shall contain at least one of the following elements in the minimum quantity given: chromium 0,30 %, nickel 0,30 %, molybdenum 0,20 %, vanadium 0,10 %. Where elements are specified in combinations of two, three or four and have alloy contents less than those given above, the limit value to be applied for steel class determination is 70 % of the sum of the individual limit values shown above for the two, three or four elements concerned.
h. A metallographically detectable white phosphorus enriched layer is not permitted for property class 12.9/12.9. It shall be detected by a suitable test method.
i. Caution is advised when the use of property class 12.9/12.9 is considered. The capability of the fastener manufacturer, the service conditions and the wrenching methods should be considered. Environments may cause stress corrosion cracking of fasteners as processed as well as those coated.

ISO 898-1 Mechanical Requirements

No.	Mechanical or physical property		Property class
			4.6	4.8	5.6	5.8	6.8	8.8		9.8 d ≤ 16 mm	10.9	12.9/ 12.9
			4.6	4.8	5.6	5.8	6.8	d≤ 16 mm	d > 16 mm	9.8 d ≤ 16 mm	10.9	12.9/ 12.9
1	Tensile strength, Rm, MPa	nom.c	400		500		600	900		900	HXll	1200
1	Tensile strength, Rm, MPa	min.		420	500	520	600	800	830	900	100	1220
2	Lower yield strength, ReL d, MPa	nom.c	240	-	300	-	-	-	-	-	-	-
2	Lower yield strength, ReL d, MPa	min.	240	-	300	-	-	-	-	-	-	-
3	Stress at 0,2 % non· proportional elongation, Rp0.2' MPa	nom.c	-	-	-	-	-	640	640	720	900	1080
3	Stress at 0,2 % non· proportional elongation, Rp0.2' MPa	min.	-	-	-	-	-	640	660	720	940	1100
4	Stress at 0,0048 d non-proportional elongation for full-size fasteners, Rpf, MPa	nom.c	-	320	-	400	480	-	-	-	-	-
4		min.	-	340e	-	420e	48e	-	-	-	-	-
5	Stress under proof load, Sp,f,MPa	nom.c	225	310	280	380	440	580	600	650	830	970
5	Proof strength ratio Sp,nom/ReL min or Sp,nom/Rp0,2 min or Sp,nom/Rpf min	min.	094	091	0.93	090	0.92	0.91	0.91	0.90	0.88	0.88
6	Percentage elongation after fracture for machined test pieces, A, %	min.	22	-	20	-	-	12	12	10	9	8
7	Percentage reduction of area after fracture for machined test pieces, Z, %	min.	-					52		48	48	44
8	Elongation after fracture for full-size fasteners, Af (see also Annex C)	min.	-	0.24	-	0.22	0.20	-	-	-	-	-
9	Head soundness		No fracture
10	Vickers hardness, HV F W 98 N	min.	120	130	155	160	190	250	255	290	320	385
10	Vickers hardness, HV F W 98 N	max.	220 g				250	320	335	360	380	435
11	Brinell hardness, HBW F = 30 D2	min.	114	124	147	152	181	238	242	276	304	366
11	Brinell hardness, HBW F = 30 D2	max.	209 g				238	304	318	342	361	414
12	Rockwell hardness, HRB	min.	67	71	79	82	89	-
	Rockwell hardness, HRB	max.	95,0 g				99,5	-
	Rockwell hardness, HRC	min.	-					22	23	28	32	39
	Rockwell hardness, HRC	max.	-					32	34	37	39	44
13	Surface hardness, HV 0,3 max.		-							h	h, i	h, j
14	Height of non-decarburized thread zone, E, mm	min.	-					1/2 H1			2 /3 H1	3 /4H1
14	Depth of complete decarburization in the thread, G, mm	max.	-					0,015
15	Reduction of hardness after retempering, HV	max.	-					20
16	Breaking torque, MB, Nm	min.	-					in accordance with ISO 898-7
17	Impact strength, KV k, l, J	min.	-			27	-	27	27	27	27	m
18	Surface integrity in accordance with	ISO 6157-1 n						ISO 6157-3

Note:
a. Values do not apply for structural bolting.
b. For structural bolting d W M12.
c. Nominal values are specified only for the purpose of the designation system for property classes. See Clause 5.
d. In cases where the lower yield strength ReL cannot be determined, it is permissible to measure the stress at 0,2 % non-proportional elongation Rp0,2.
e. For the property classes 4.8, 5.8 and 6.8 the values for Rpf min are under investigation. The present values are given for calculation of the proof stress ratio only. They are not test values.
f. Proof loads are specified in Tables 5 and 7.
g. Hardness determined at the end of a fastener shall be 250 HV, 238 HB or 99,5 HRB maximum.
h. Surface hardness shall not be more than 30 Vickers points above the measured core hardness of the fastener when determination of both surface hardness and core hardness are carried out with HV 0,3.
i. Any increase in hardness at the surface which indicates that the surface hardness exceeds 390 HV is not acceptable.
j. Any increase in hardness at the surface which indicates that the surface hardness exceeds 435 HV is not acceptable.
k. Values are determined at a test temperature of −20 °C, see 9.14.
l.Applies to d W 16 mm.
m. Value for KV is under investigation.
n. Instead of ISO 6157-1, ISO 6157-3 may apply by agreement between the manufacturer and the purchaser.

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DIN931-933 Class 4.8 and 6.8 and 8.8 and 10.9 and 12.9 Hexagon Head Bolts