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
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 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
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    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.


    @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.

    @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.

    for A307A how its measurement mention in MTC ..? in inch or Metric ,why..?
    suppose if mention in metric(eg:M12x100) in mtc its is acceptable..? please replay

    @Nisa- We are sorry, but are unsure of what you are asking. We sell and can manufacture inch-dimensioned products. We do not handle metrics nor do we know much about them.


    Can you please advise for below alternative Bolts/Nuts material. Application is Deaerator Columns, for bolting Columns to module structure:

    1. ASTM A325M T-1 in place of Gr. 8.8 for Bolts
    2. A194 Gr 2H in place of ASTM A563 Gr. DH for Nuts

    @Bilal- For the bolts, those grades are very similar from a chemical and mechanical standpoint, but any substitution should approved by the project engineer as there are subtle differences between the two. For the nuts, A194 2H is an allowable substitution per ASTM.

    is it possible to use 10.9 as equivalent to a193 b7?
    as I know, A193 B7 bolt is low alloy steel fit to high temprature service up to around 400 C, while all bolts manufactured to iso 898 (such like 10.9) is normally applicable to be used only under 150 C.
    So Im worry that 10.9 cannot replace B7 bolt in high temprature service.

    @Abdelaziz- You are correct, 10.9 should not be substituted for A193 B7 without an engineer’s approval. B7 is formulated for high temperature applications, whereas 10.9 is for general purpose use.

    is that ok to use material C1015 to produce the item which requires grade 5.8?
    kindly ask you to reply, thank you

    @Leon- As long as the C1015 material you chose to use meets the mechanical and chemical requirements of 5.8, then you can use it. C1015 is typically furnished as chemicals only, so you may need to test it to assure the proper mechanical requirements are met.

    @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.

    @Prashun- Apologies, but we are not familiar enough with all the various ISO standards to know which grade is the closest equivalent.

    @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.

    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.

    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- 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

    @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.

    @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.

    what is the equivalent ASTM bolt for DIN-933 and DIN-6914. is it possible to change A325 and A490 bolts with these DIN Bolts. is there reference for the same.

    @Ranjith- Thank you for your question, but we are unfamiliar with the DIN standards, so cannot help in this case. Apologies.

    First off thank you for all the technical information Portland Bolt has brought together and made available to the public. I find myself here almost every work day.

    Is it acceptable to use the A193 GR B8 and B8M as a rough equivalent for metric 304 and 316 stainless steel bolts? Also, does the A449 have to be used or is it acceptable to use SAE J429 Gr 5 as a material specification for plain carbon steel metric bolts. I just want to avoid creating issues for our procurement team by using the wrong spec?

    @Michael- B8 and B8M is 304 and 316, respectively. As long as you convert the diameter units, using B8/B8M should be fine. As for A449/gr.5, neither will be available (as far as I know) in metric. The approximate metric equivalent to A449/gr.5 is ISO 898 gr.8.8. Those should be pretty easily obtainable.

    We want to go for Anchor bolts with SI system. For that i found A563M-04 for Nuts, F436M-93 for washers, but F1554 for anchor bolts is available only with FPS system. What shall be refered for its SI equivalent. I failed to found it. Requested to give your openion.

    @Vasant – I am not aware of any direct metric equivalent for F1554. That said, if you can find a manufacturer who can manufacture to metric dimensions, there is no reason they cannot just make bolts to meet the chemical and mechanical requirements of F1554, but with metric dimensions.

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