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 |
Good Morning,
I was asked to use a DIN931 – M20X90-10.9D1G bolt. Would an A325 Galv Assembly be comparable (I know I would have to get approval from my engineer but metric is proving to be difficult to find).
Thanks
@James- Grade 10.9 is a slightly higher strength fastener than ASTM A325 (approximately 150ksi vs 120ksi tensile), and will have slightly different dimensions(head size, thread length). It is certainly possible that an A325 will work in your application, but you are correct in needing an engineer to approve that kind of substitution.
Dear Dane,
Could we use B7 studbolt in place of G.12.9 studbolt?
@Soebroto- We don’t think that a B7 bolt is as strong as a 12.9 bolt, so you would need to have that substitution approved by the project engineer.
what is the Diffrence between the A490 M & 10S,can you explain?
@Mashkoor- An A490M bolt is a male threaded heavy hex structural bolt, whereas the A563 10S is the female threaded heavy hex nut used with the aforementioned bolt.
Greetings to ALL,
My black finished 10.9 grade nut and bolts are getting rusty. How can I avoid it as I cant do hot dip galvanization due to Hydrogen embritlement according to ASTM F 568 Section 4.6 and Note 1.
@Asad- You are correct that caution should be used when galvanizing 10.9 bolts. There are several other coating options; zinc, Geomet, or other various proprietary coatings that are alternatives to hot dip galvanizing. F568M, which is no longer in use, does not prohibit other coatings. ISO 898-1 is the current standard for metric 10.9, 8.8, 12.9 etc grades, and it may have different coating guidelines, but we are not as familiar with the ISO standard, so are unable to discuss thoroughly.
Is it permissible (by Code) to reuse previously torqued (torqued to specification) ASTM325, ASTM325M and Grade 8.8 bolts
@Ramiz- The AISC says that galvanized A325 bolts shall never be reused, whereas for plain finish bolts they can be used at the discretion of the project engineer. We are not aware of any such guidelines for 8.8 bolts. https://www.portlandbolt.com/technical/faqs/rules-for-reusing-bolts/