ISO 3506-1 Mechanical Properties of Stainless Steel Fasteners

Performance Grade Marking System for Stainless Steel Fasteners (ISO 3506-1:2020)

Chemical Composition of Stainless Steel (ISO 3506-1:2020)

Chemical composition (cast analysisi, mass fraction in %)		C	Si	Mn	P	S	Cr
A1	Austenitic stainless steel	0.12	1	6.5	0.02	0.15~0.35	16.0~19.0
A2		0.1	1	2	0.05	0.03	15.0~20.0
A3		0.08	1	2	0.045	0.03	17.0~19.0
A4		0.08	1	2	0.045	0.03	16.0~18.5
A5		0.08	1	2	0.045	0.03	16.0~18.5
A8		0.03	1	2	0.04	0.03	19.0~22.0
C1	Martensitic stainless steel	0.09~0.15	1	1	0.05	0.03	11.5~14.0
C3		0.17~0.25	1	1	0.04	0.03	16.0~18.0
C4		0.08~0.15	1	1.5	0.06	0.15~0.35	12.0~14.0
F1	Ferritic stainless steel	0.08	1	1	0.04	0.03	15.0~18.0
D2	Duplex stainless steel	0.04	1	6	0.04	0.03	19.0~24.0
D4		0.04	1	6	0.04	0.03	21.0~25.0
D6		0.03	1	2	0.04	0.015	21.0~23.0
D8		0.03	1	2	0.035	0.015	24.0~26.0

Chemical composition (cast analysisi, mass fraction in %)		Mo	Ni	Cu	N	Other Elements and Notes
A1	Austenitic SS	0.7	5.0~10.0	1.75~2.25	/	c,d,e
A2		/ f	8.0~19.0	4	/	g,h
A3		/ f	9.0~12.0	1	/	5C≤Ti≤0.80 and/or 10C≤Nb≤1.00
A4		2.00~3.00	10.0~15.0	4	/	h,i
A5		2.00~3.00	10.5~14.0	1	/	5C≤Ti≤0.80 and/or 10C≤Nb≤1.00 i
A8		6.0~7.0	17.5~26.0	1.5	/	/
C1	Martensitic SS	/	1	/	/	i
C3		/	1.50~2.50	/	/	/
C4		0.6	1	/	/	c,i
F1	Ferritic SS	/ f	1	/	/	j
D2	Duplex SS	0.10~1.00	1.50~5.5	3	0.05~0.20	Cr+3.3Mo+16N≤24.0 k
D4		0.10~2.00	1.00~5.5	3	0.05~0.30	24.0＜Cr+3.3Mo+16N k
D6		2.5~3.5	4.5~6.5	/	0.08~0.35	/
D8		3.00~4.5	6.0~8.0	2.5	0.20~0.35	W≤1.00
①, a. Unless otherwise indicated, all values ​​are maximum values. ②, b. In case of dispute, product analysis applies. ③, c. Selenium can be used to replace sulfur, but its use may be restricted. d. If the mass fraction of nickel is less than 8%, the minimum mass fraction of manganese must be 5%. e. When the mass fraction of nickel is greater than 8%, there is no limit on the minimum content of copper. f. Molybdenum content may appear in the manufacturer’s instructions. However, for some use cases, if it is necessary to limit the limit content of molybdenum, it must be specified by the user in the order. ④, g. If the mass fraction of chromium is less than 17%, the minimum mass fraction of nickel should be 12%. h. For austenitic stainless steel with a maximum carbon mass fraction of 0.03%, the nitrogen mass fraction can reach a maximum of 0.22%. ⑤, i. For products with larger diameters, in order to achieve the specified mechanical properties, the carbon content may be higher in the manufacturer’s instructions, but it should not exceed 0.12% for austenitic steel. ⑥, j. May include titanium and/or niobium to improve corrosion resistance. ⑦, k. This formula is used solely for the purpose of classifying duplex steels in accordance with this document (it is not intended to be used as a selection criterion for corrosion resistance).

Mechanical Properties of Stainless Steel Bolts, Screws, and Studs – Austenitic and Duplex Stainless Steels

Stainless steel grade		A1 A2 A3	A1 A2 A3	A1 A2 A3	A4 A5	A4 A5	A4 A5	A4 A5	A8	A8	A8	D2 D4 D6 D8	D2 D4 D6 D8	D2 D4 D6 D8
Type		Austenitic	Austenitic	Austenitic	Austenitic	Austenitic	Austenitic	Austenitic	Austenitic	Austenitic	Austenitic	Duplex SS	Duplex SS	Duplex SS
Performance Grade		50	70	80	50	70	80	100	70	80	100	70	80	100
Tensile Strength Rmf	min / MPa	500	700	800	500	700	800	1000	700	800	1000	700	800	1000
The stress at 0.2% plastic elongation Rpf	min / MPa	210	450	600	210	450	600	800	450	600	800	450	600	800
Elongation at break A	min / mm	0.6d	0.4d	0.3d	0.6d	0.4d	0.3d	0.2d	0.4d	0.3d	0.2d	0.4d	0.3d	0.2d

Mechanical Properties of Stainless Steel Bolts, Screws, and Studs – Martensitic and Ferritic Steel Groups

Stainless steel grade		C1-50	C1-70	C1-110 ①	C3-80	C4-50	C4-70	F1-45 ②	F1-60 ②
Type		Martensitic SS	Martensitic SS	Martensitic SS	Martensitic SS	Martensitic SS	Martensitic SS	Ferritic SS	Ferritic SS
Tensile Strength Rmf	min / MPa	500	700	1100	800	500	700	450	600
The stress at a plastic elongation of 0.2%Click to apply Rpf	min / MPa	250	410	820	640	250	410	250	410
Elongation at break A	min / mm	0.2d	0.2d	0.2d	0.2d	0.2d	0.2d	0.2d	0.2d
HV	Hardness Range	155~220	220~330	350~440	240~340	155~220	220~330	135~220	180~285
HRC		/	20~34	36~45	21~35	/	20~34	/	/
HBW		147~209	209~314	/	228~323	147~209	209~314	128~209	171~271
① Quenched and tempered, with a minimum tempering temperature of 275°C.
② Thread nominal diameter ≤ 24 mm.

Mechanical Properties of Stainless Steel Bolts, Screws, and Studs – Minimum Tensile Load F_mf / N – Coarse Thread

Thread				M3	M3.5	M4	M5	M6	M7	M8	M10	M12	M14
Nominal Stress Cross-sectional Area As / mm2				5.03	6.78	8.78	14.2	20.1	28.9	36.6	58	84.3	115
50 ①	Austenitic and Duplex Stainless Steel			2 520	3 390	4 390	7 100	10 070	14 430	18 310	29 000	42 140	57 720
70				3 530	4 750	6 150	9 930	14 090	20 210	25 630	40 600	58 990	80 810
80				4 030	5 430	7 030	11 350	16 100	23 090	29 290	46 400	67 420	92 360
100				5 040	6 780	8 780	14 190	20 130	28 860	36 610	57 990	84 270	115 500
50	Martensitic Stainless Steel			2 520	3 390	4 390	7 100	10 070	14 430	18 310	29 000	42 140	57 720
70				3 530	4 750	6 150	9 930	14 090	20 210	25 630	40 600	58 990	80 810
80				4 030	5 430	7 030	11 350	16 100	23 090	29 290	46 400	67 420	92 360
110				5 540	7 460	9 660	15 610	22 140	31 750	40 270	63 790	92 700	127 000
45	Ferritic Stainless Steel			2 270	3 050	3 960	6 390	9 060	12 990	16 480	26 100	37 920	51 950
60				3 020	4 070	5 270	8 510	12 080	17 320	21 970	34 800	50 560	69 270

Thread				M16	M18	M20	M22	M24	M27	M30	M33	M36	M39
Nominal Stress Cross-sectional Area As / mm2				157	192	245	303	353	459	561	694	817	976
50 ①	Austenitic and Duplex Stainless Steel			78 340	96 240	122 400	151 700	176 300	229 800	280 300	346 800	408 400	487 900
70				109 700	134 800	171 400	212 400	246 800	321 600	392 500	485 500	571 800	683 100
80				125 400	154 000	195 900	242 800	282 100	367 600	448 500	554 900	653 400	780 700
100				156 700	192 500	244 800	303 400	352 600	459 500	560 600	693 600	816 800	975 800
50	Martensitic Stainless Steel			78 340	96 240	122 400	151 700	176 300	229 800	280 300	346 800	408 400	487 900
70				109 700	134 800	171 400	212 400	246 800	321 600	392 500	485 500	571 800	683 100
80				125 400	154 000	195 900	242 800	282 100	367 600	448 500	554 900	653 400	780 700
110				172 400	211 800	269 300	333 800	387 800	505 400	616 700	763 000	898 400	1 073 400
45	Ferritic Stainless Steel			70 510	86 620	110 200	136 600	158 700	/	/	/	/	/
60				94 010	115 500	146 900	182 100	211 600	/	/	/	/	/

Mechanical Properties of Stainless Steel Bolts, Screws, and Studs – Minimum Tensile Load at R_pf / N – Coarse Thread

Thread				M3	M3.5	M4	M5	M6	M7	M8	M10	M12	M14
Nominal Stress Cross-sectional Area As / mm2				5.03	6.78	8.78	14.2	20.1	28.9	36.6	58	84.3	115
50 ②	Austenitic and Duplex Stainless Steel			1 060	1 430	1 850	2 980	4 230	6 070	7 690	12 180	17 700	24 250
70				2 270	3 050	3 960	6 390	9 060	12 990	16 480	26 100	37 920	51 950
80				3 020	4 070	5 270	8 510	12 080	17 320	21 970	34 800	50 560	69 270
100				4 030	5 430	7 030	11 350	16 100	23 090	29 290	46 400	67 420	92 360
50	Martensitic Stainless Steel			1 260	1 700	2 200	3 550	5 040	7 220	9 160	14 500	21 070	28 860
70				2 070	2 780	3 600	5 820	8 260	11 840	15 010	23 780	34 550	47 340
80				3 220	4 340	5 620	9 080	12 880	18 480	23 430	37 120	53 940	73 890
100				4 130	5 560	7 200	11 630	16 510	23 670	30 020	47 560	69 100	94 670
45	Ferritic Stainless Steel			1 260	1 700	2 200	3 550	5 040	7 220	9 160	14 500	21 070	28 860
60				2 070	2 780	3 600	5 820	8 260	11 840	15 010	23 780	34 550	47 340

Thread				M16	M18	M20	M22	M24	M27	M30	M33	M36	M39
Nominal Stress Cross-sectional Area As / mm2				157	192	245	303	353	459	561	694	817	976
50 ②	Austenitic and Duplex Stainless Steel			32 910	40 420	51 410	63 720	74 030	96 480	117 800	145 700	171 600	205 000
70				70 510	86 620	110 200	136 600	158 700	206 800	252 300	312 100	367 600	439 100
80				94 010	115 500	146 900	182 100	211 600	275 700	336 400	416 200	490 100	585 500
100				125 400	154 000	195 900	242 800	282 100	367 600	448 500	554 900	653 400	780 700
50	Martensitic Stainless Steel			39 170	48 120	61 200	75 850	88 130	114 900	140 200	173 400	204 200	244 000
70				64 240	78 920	100 400	124 400	144 600	188 400	229 900	284 400	334 900	400 100
80				100 300	123 200	156 700	194 200	225 700	294 100	358 800	443 900	522 800	624 500
100				128 500	157 900	200 800	248 800	289 100	376 800	459 700	568 800	669 800	800 200
45	Ferritic Stainless Steel			39 170	48 120	61 200	75 850	88 130	/	/	/	/	/
60				64 240	78 920	100 400	124 400	144 600	/	/	/	/	/

Mechanical Properties of Stainless Steel Bolts, Screws, and Studs – Minimum Tensile Load F_mf / N – Fine Thread

①, Grade 50 refers exclusively to austenitic grades A1 through A5.
②, Unit: Newton (N)

Thread				M8x1	M10x1.25	M10x1	M12x1.5	M12x1.25	M14x1.5	M16x1.5	M18x1.5	M20x2
Nominal Stress Cross-sectional Area As / mm2				39.2	61.2	64.5	88.1	92.1	125	167	216	258
50	Austenitic and Duplex Stainless Steel			19 590	30 600	32 250	44 070	46 040	62 280	83 630	108 200	129 000
70				27 420	42 840	45 150	61 690	64 460	87 190	117 100	151 400	180 600
80				31 340	48 960	51 600	70 510	73 660	99 640	133 800	173 000	206 400
100				39 170	61 200	64 500	88 130	92 080	124 600	167 300	216 300	258 000
50	Martensitic Stainless Steel			19 590	30 600	32 250	44 070	46 040	62 280	83 630	108 200	129 000
70				27 420	42 840	45 150	61 690	64 460	87 190	117 100	151 400	180 600
80				31 340	48 960	51 600	70 510	73 660	99 640	133 800	173 000	206 400
100				43 090	67 320	70 950	96 940	101 300	137 100	184 000	237 900	283 800
45	Ferritic Stainless Steel			17 630	27 540	29 030	39 660	41 440	56 050	75 270	97 310	116 100
60				23 510	36 720	38 700	52 880	55 250	74 730	100 400	129 800	154 800

Thread				M20x1.5	M22x1.5	M24x2	M27x2	M30x2	M33x2	M36x2	M39x2
Nominal Stress Cross-sectional Area As / mm2				272	333	384	496	621	761	865	1030
50	Austenitic and Duplex Stainless Steel			135 800	166 600	192 300	247 900	310 700	380 400	432 500	514 200
70				190 100	233 200	269 100	347 100	434 900	532 600	605 500	719 900
80				217 300	266 500	307 600	396 600	497 000	608 700	692 000	822 800
100				271 600	333 100	384 500	495 800	621 300	760 800	865 000	1 028 400
50	Martensitic Stainless Steel			135 800	166 600	192 300	247 900	310 700	380 400	432 500	514 200
70				190 100	233 200	269 100	347 100	434 900	532 600	605 500	719 900
80				217 300	266 500	307 600	396 600	497 000	608 700	692 000	822 800
100				298 700	366 400	422 900	545 400	683 400	836 900	951 500	1 131 300
45	Ferritic Stainless Steel			122 200	149 900	173 000	/	/	/	/	/
60				163 000	199 900	230 700	/	/	/	/	/

Mechanical Properties of Stainless Steel Bolts, Screws, and Studs – Minimum Tensile Load at R_pf/ N – Fine Thread

①, Grade 50 refers exclusively to austenitic grades A1 through A5.
②, Unit: Newton (N)

Thread				M8x1	M10x1.25	M10x1	M12x1.5	M12x1.25	M14x1.5	M16x1.5	M18x1.5	M20x2
Nominal Stress Cross-sectional Area As / mm2				39.2	61.2	64.5	88.1	92.1	125	167	216	258
50 ①	Austenitic and Duplex Stainless Steel			8 230	12 860	13 550	18 510	19 340	26 160	35 130	45 410	54 180
70				17 630	27 540	29 030	39 660	41 440	56 050	75 270	97 310	116 100
80				23 510	36 720	38 700	52 880	55 250	74 730	100 400	129 800	154 800
100				31 340	48 960	51 600	70 510	73 660	99 640	133 800	173 000	206 400
50	Martensitic Stainless Steel			9 800	15 300	16 130	22 040	23 020	31 140	41 820	54 060	54 180
70				16 060	25 100	26 450	36 140	37 750	51 070	68 580	88 660	116 100
80				25 070	39 170	41 280	56 410	58 930	79 710	107 100	138 400	154 800
100				32 120	50 190	52 890	72 270	75 500	102 200	137 200	177 400	211 600
45	Ferritic Stainless Steel			9 800	15 300	16 130	22 040	23 020	31 140	41 820	54 060	54 180
60				16 060	25 100	26 450	36 140	37 750	51 070	68 580	88 660	116 100

Thread				M20x1.5	M22x1.5	M24x2	M27x2	M30x2	M33x2	M36x2	M39x2
Nominal Stress Cross-sectional Area As / mm2				272	333	384	496	621	761	865	1030
50 ①	Austenitic and Duplex Stainless Steel			57 020	69 950	80 730	104 200	130 500	159 800	181 700	216 000
70				122 200	149 900	173 000	223 100	279 600	342 400	389 300	462 800
80				163 000	199 900	230 700	297 500	372 800	456 500	519 000	617 100
100				217 300	266 500	307 600	396 600	497 000	608 700	692 000	822 800
50	Martensitic Stainless Steel			67 880	83 270	96 110	124 000	155 400	190 200	216 300	257 100
70				111 400	136 600	157 700	203 300	254 700	312 000	354 700	421 700
80				173 800	213 200	246 100	317 300	397 600	487 000	553 600	658 200
100				222 700	273 200	315 300	406 600	509 400	623 900	709 300	843 300
45	Ferritic Stainless Steel			67 880	83 270	96 110	/	/	/	/	/
60				111 400	136 600	157 700	/	/	/	/	/

Mechanical Properties of Stainless Steel Bolts, Screws, and Studs – Minimum Breaking Torque MB – Austenitic Steel

Unit：Nm

Thread		M1.6	M2	M2.5	M3	M4	M5	M6	M8	M10	M12	M16
50	Performance Grade	0.15	0.3	0.6	1.1	2.7	5.5	9.3	23	46	80	210
70		0.2	0.4	0.9	1.6	3.8	7.8	13	32	65	110	290
80		0.24	0.48	0.96	1.8	4.3	8.8	15	37	74	130	330