The steelmaker who creates a transition curve for the original manufactured material. Or, the fabricator who does the same after forming it. There is no standard DBTT because there are so many specific variables that contribute to the toughness characteristics.
Maybe the more relevant question is , what is the minimum design temperature that the above steels can be used without the need for impact testing to establish a DBTT?
Reply; Go to ASME B&PV Code, Section VIII, Div 1 and what you will find are impact exemption curves that have been developed over the years for a group of steels, which the above are included, to ensure a minimum impact energy value for a given service temperature and material thickness.
-20 deg F if not normalized, and less than 0.5" in thickness
-55 deg F if normalized and less than 0.5" in thickness
If the thickness or use of the steel is below a minimum service temperature based on the exemption curves above, impact testing will be required to that heat of material.
Doing some research for a project and got googled right to this thread.
A question to stanweld. Following up on the pervious post, if impact tested to zone 3 of table 9 of ASTM A709, wouldn't it be good to -60F per Table 7?
rmw,
I'm not sure what question you are asking. SA-516 70 is not referenced under A-709. A709, S84 does not apply to ASME B & PV Codes. Impact test temperatures and absorbed energy are based on other (ASHTO) design criteria.
