Fasteners - Strength of Metric Fasteners (Carbon and Stainless Steel)

Tensile and Proof Stress Of Metric Bolts and Screws.

Table of absolute maximum axial tensile loads on bolts or threaded rod (in N) for common bolt designations / grades. Calcs by Dave

			Carbon Steel grades								Stainless A2 grades
M	Pitch	3.6	4.6	4.8	5.6	5.8	6.8	8.8	10.9	12.9	50	70	80	100
3	0.5	1666	2019	2120	2524	2625	3028	4038	5047	6057	2524	3533	4038	5047
3.5	0.6	2244	2720	2855	3399	3535	4079	5439	6799	8159	3399	4759	5439	6799
4	0.7	2908	3524	3701	4405	4582	5286	7049	8811	10573	4405	6168	7049	8811
5	0.8	4694	5690	5974	7112	7397	8535	11380	14224	17069	7112	9957	11380	14224
6	1	6662	8076	8479	10094	10498	12113	16151	20189	24227	10094	14132	16151	20189
7	1	9545	11570	12149	14463	15041	17355	23140	28925	34710	14463	20248	23140	28925
8	1.25	12115	14684	15419	18355	19090	22026	29369	36711	44053	18355	25698	29369	36711
10	1.5	19185	23255	24417	29068	30231	34882	46509	58137	69764	29068	40696	46509	58137
12	1.75	27874	33787	35476	42233	43923	50680	67574	84467	101360	42233	59127	67574	84467
14	2	38181	46280	48594	57851	60165	69421	92561	115701	138841	57851	80991	92561	115701
16	2	51787	62772	65911	78465	81604	94158	125544	156930	188316	78465	109851	125544	156930
18	2.5	63651	77153	81010	96441	100299	115729	154305	192882	231458	96441	135017	154305	192882
20	2.5	80917	98081	102985	122602	127506	147122	196163	245203	294244	122602	171642	196163	245203
22	2.5	100257	121523	127600	151904	157980	182285	243047	303808	364570	151904	212666	243047	303808
24	3	116521	141237	148299	176546	183608	211856	282474	353093	423712	176546	247165	282474	353093
27	3	151799	183998	193198	229998	239198	275997	367996	459995	551995	229998	321997	367996	459995
30	3.5	185258	224556	235783	280694	291922	336833	449111	561389	673667	280694	392972	449111	561389
33	3.5	229137	277742	291629	347178	361065	416613	555484	694355	833226	347178	486049	555484	694355
36	4	269864	327108	343463	408885	425240	490662	654216	817770	981324	408885	572439	654216	817770
39	4	322344	390720	410256	488400	507936	586080	781440	976800	1172160	488400	683760	781440	976800

Carbon Steel

Indicated stresses in Newton/mm²

Strength Designation	3.6	4.6	4.8	5.6	5.8	6.8	8.8	8.8	9.8	10.9	12.9
							=< 16mm	> 16
Nom. Tensile Strength	300	400	400	500	500	600	800	800	900	1000	1200
Min Tensile Strength	330	400	420	500	520	600	800	830	900	1000	1200
Lower Yield Stress	180/190	240	320/340	300	400/420	480	-	-	-	-	-
Stress at Perm. Set	-	-	-	-	-	-	640	640/660	720	900/940	1080/100

In accordance with BS 3692:2001 and BS EN IOS 898-1 : 1999

Tensile Strength Of Metric Nuts

Indicated stresses in Newton/mm²

Strength Designation	4	5	6	8	10	12
Tensile Strength	400	500	600	800	1000	1200

In accordance with BS 3692:2001

The designation system allows the determination of the ultimate and yield/proof strength of the bolt. The designation system is based on two numbers e.g 8.8 .  The first number is the tensile strength of the bolt material (N2 )/100.  The second number is = 1/100.(the ratio of the Proof (or Yield ) stress and the Tensile strength expressed as a percentage = 100.[Yield (Proof stress) /Tensile strength] /100

The tensile and proof strength of the steel for a 4.6 bolt is therefore calculated as follows Tensile strength (Rm) = 4.100 N/mm2 = 400 N/mm2 .... Proof strength (R0,2) = 0,6*400 * 100 /100 = 240 N/mm2

Stainless Steel

Stainless steels include Austenitic, Martensitic and Ferritic..

Austenitic stainless steels.. Chromium nickel steels which can be cold worked. Non magnetic. Associated grades ( Steel Number according to BS EN 10088 pt 1) = A1 (1.4305) , A2 (1.4301 - 304) ,A3 (1.4541) , A4 (1.4401 - 316) and A5 (1.4571).

Martensitic stainless steels .. Limited corrosion resistance but can be heat treated for superior strength properties. Magnetic Properties. Associated grades ( Steel Number according to BS EN 10088 pt 1) = C1 (1.4006 etc) , C3 (1.4057), C4(1.4104)

Ferritic stainless steels .. Plain chromium stainless steels with a chromium content varying between 10.5 and 18% and a low carbon content. They not hardenable by heat treatment. Ferritic alloys have good ductility and formability but a relatively poor high temperature strength compared austenitic grades. Magnetic.. Associated grades = F1 Tensile and Proof Stress Of Metric Bolts and Screws. (Stainless Steel )

Indicated stresses in Newton/mm²

Stainless Steel	Austenitic				Martensitic				Ferritic
Steel Grade	A1, A2, A3, A4, A5				C1,C4		C1	C3	F1
Strength class	50	70	80	100	50	70	110	80	45	60
Tensile Strength	500	700	800	1000	500	700	1100	800	450	600
0,2% proof stress	210	450	600	750	250	410	820	640	250	410