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 |
Can i use 8.8 grade bolts instead of ASTM A325M
@Remis- You would need to have that substitution approved by the project engineer. There are similarities between those bolts, but some differences as well.
Yes, it can be substituted each other (ASTM A325M bolt is equivalent to the properties of an ASTM F568 Class 8.8 (ISO 898/I) And please refer to Section 4.1 of ASTM A325M.
Hello Dane, Could you please help me. Can a Grade 8.8 foundation bolt be used at minus 25 Centigrade. Many thanks in advance, regards, David.
@David- We don’t have a lot of experience with 8.8 bolts, so we are not sure how they would perform in cold temperatures. A charpy test would tell you if the 8.8 bolts maintain their ductility at cold temperatures.
High, Can you tell me the CTE of a grade 8.8 bolt?
Thanks
@Chris- Apologies, but we are unsure what CTE means. If you could clarify, we’d be happy to help if we can.
what is ISO grade equivalent to A307 GRADE B
@Prashun- Apologies, but we are not familiar enough with all the various ISO standards to know which grade is the closest equivalent.
what is ISO grade equivalent to A307 GRADE B
@Eman- Apologies but we are not familiar enough with ISO fastener standards to know what the equivalent would be.
Can Grade 8.8 bolts be used against A193 B7 requirement?
@KK-No, A193 B7 is a high strength bolting material designed for high temperature, high pressure applications. Grade 8.8 is a medium strength bolt for general purpose applications. They should not be substituted without approval from the project engineer.