What are the imperial/ASTM equivalents for metric fastener grades?
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|
|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||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|