What are the differences between A36 and A307?

ASTM A36 is a steel (raw material) specification, while ASTM A307 is a fastener specification. In other words, once you take A36 round bar and cut it, thread it, bend it, forge a head on it, or otherwise process it and turn it into a fastener, it becomes an A307 bolt.

Often times, ASTM A307 bolts (and all thread rod) are manufactured from A36 steel, but not always. A36 material should always be weldable and if A307 rods are manufactured from A36 steel, they will be weldable as well. However, A307 bolt can be made from other steels which, in rare instances, may not be weldable. Specify the supplemental requirement “S1” which is the A307 specification that outlines the requirements for weldability. If a steel other than A36 is used to manufacture the A307 rods, the chemistry should be checked to assure weldability.

Written December 14, 2007 by
Dane McKinnonDane McKinnon

Phone: 503.219.6991


    Dear Dane

    Our clients request UBOLT according to ASTM A307 Grade B.
    In this case it can be manufactured with bars on A-36?.
    I await your prompt response.

    Thank you.

    @Yanniz- It is possible, yes, however A307B does have some requirements that A36 does not, so you would need to make sure your A36 has the necessary testing to meet A307B.

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