Both ASTM F568M and ISO 898-1 outline several grades of metric fastener, from low carbon/low strength, up to high strength/heat treated alloy grades. The equivalents listed below should be only considered as rough equivalents. Special care should be taken before substituting grades to make sure that an acceptable substitute is being used. For example, grade 8.8 has the same mechanical requirements all the way up to M80 (3-1/8”), however the ASTM equivalent, A449, lowers its mechanical requirements as the diameter increases, necessitating a conversation between the purchaser and manufacturer to decide the best way of satisfying the necessary mechanical requirements. Similarly, grade 12.9, where as common in metric circles, has as its only ASTM mechanical equivalent, A574. A574, however, is a socket head cap screw standard, so studs and hex bolts are left out and do not have a direct equivalent.
Portland Bolt is happy to help if you have specific questions or needs. We cannot manufacture metric sizes or bolts to metric grades, and we are not able to make recommendations, but we can work with you to determine what is feasible and cost effective if a substitution is allowed.
As always, an engineer should be consulted before grade substitutions are made.
| Diameter Range | Metric Grade | Approximate ASTM Equivalent | Description | Tensile, min | Yield, min | ||
|---|---|---|---|---|---|---|---|
| Mpa | ksi | Mpa | ksi | ||||
| All | 4.6 | A307A | Low or medium carbon steel | 400 | 58 | 240 | 35 |
| through 1" (M24) | 5.8 | - | Cold worked low or medium carbon steel | 520 | 75 | 420 | 61 |
| through 1" (M24) | 8.8 | A449 / F3125 Grade A325 | Heat treated medium carbon steel | 830 | 120 | 660 | 96 |
| above 1" (M24) | 8.8 | A193B7/A354BC or F1554G105 | Heat treated medium carbon steel | 830 | 120 | 660 | 96 |
| through 1-1/2" (M36) | 8.8.3 | A325 Type 3 / A449 Type 3 | Heat treated medium carbon weathering steel | 830 | 120 | 660 | 96 |
| All | 10.9 | A490/A354BD | Heat treated medium carbon alloy steel | 1040 | 151 | 940 | 136 |
| through 1-1/2" (M36) | 10.9.3 | A490 Type 3 | Heat treated medium carbon alloy weathering steel | 1040 | 151 | 940 | 136 |
| All | 12.9 | A574 | Heat treated alloy steel | 1220 | 177 | 1100 | 160 |
Hi Dane ,
Are you the contact person for your company ? I have sent a no. of enquiry but no reply at all. Kindly advise contact details. Thank you.
@Ken- If you are sending in a sales inquiry, please send it to sales@portlandbolt.com. If you are sending a purchasing inquiry, please send it to me.
Dear Dane,
Please advise. Are there any advantages (or disadvantages) in using structural bolt A325 in mm instead of in inch (for example M16 vs 5/8″ bolt) ?
Thank you and Regards,
Dinar
@Dinar- As long as the bolt meets the requirements of the application, and fits in the hole, you should be able to use either metric or imperial fasteners depending on which is more readily available.
thank u mr. McKinnon for sharing the valuable information with us…… I just want to know the Metric Equivalent for Heavy He bolt conforming to ASTM A-307, Grade B standard please…
Thank u
@Rohit- I am not aware of a direct equivalent, but ISO 898-1 gr.4.6 would be similar.
Do you have the following info for metric grade 5.8: Enlong % min, RA % min and Hardness Rockwell min and max.
@David- It does not appear that class 5.8 fasteners have any requirement for elongation or reduction of area %. The minimum hardness is 82 HRB.
Is A574 susceptible to hydrogen embrittlement in the same way as 12.9?
@Niels- Yes, A574 screws have a specified minimum tensile strength of 170-180ksi (depending on diameter), and the threshold for hydrogen embrittlement concerns is 150ksi.