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 |
Is it possible to use bolt classe 8.8 instead of A325 and A307, if ok , could you please confirm that they have the same chemical properties ( to avoid corrosion)
In order to substitute, you’d need approval from the project engineer. 8.8 bolts should have similar chemistry as A325 bolts (although not identical), but both will be quite different than an A307 bolt. None of the three will have any inherent corrosion resistance unless you choose to coat them.
Can A490 be used as a substitute for 10.9 bolts?
@Tom- Any material substitutions should be approved by the project engineer. That said, A490 bolts and 10.9 bolts have very similar mechanical requirements, so if the dimensional differences of the A490 do not cause any concern, we also see no major concern.
hello gents
could you please advise are bolts A-193 Gr.B7 can replace grade 8.8 ?
@Ashraf- A193 B7 is mechanically similar to 8.8, but can vary chemically. We do not see an issue in replacing 8.8 with B7, but as always, the project engineer should approve any substitution.
Hello Dave.
What is the advantage of using bolts 8.8 coated with hot dipped galvanized and Dacromet?
Which process would hydrogen embrittlement be the most affected.
We want to use these bolts for structural steel bases.
Thanks
George
@George – 8.8 bolts are heat treated and high strength, but not high enough strength that they are susceptible to hydrogen embrittlement. They can be hot dip galvanized without embrittlement issues. Dacromet is also allowed, but it is being discontinued due to ROHS concerns.
What is equivalent grade of EN iso 898-1
@Hareshchandra – We are not very familiar with ISO 898, but we do believe there are many grades (4.6, 8.8, 10.9, 12.9 etc) within that standard with have rough, but not exact equivalents to ASTM standards. We’d be happy to talk you through the specifics of whichever grade you are working with if you’d like to contact us through either this website, email, phone, or live chat.