ASTM A449 covers quenched and tempered steel fasteners. It is not a good idea to weld quenched and tempered steels unless due consideration is given to the chemistry, required preheat, and the realization that the mechanical properties of the fastener material is going to be degraded. The designer must also recognize the potential for cracking is enhanced by the increased carbon equivalency of the fastener material. The cracks can be in the form of hot cracks or delayed cold cracks.
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