The A27
Grade 70-40 is the strongest grade of A27, but it
does not meet the mechanical property requirements for the steel
connector.
-
The
ultimate tensile strength of 70 ksi is below the 80 ksi design goal.
-
The
tensile yield strength of 40 ksi is below the 50 ksi design goal.
-
The
elongation meets the 22% requirement, but the reduction in area
value fails
to meet the 35% target.
In addition,
the chemistry and heat treat specifications are not tight enough to permit
precise control of the alloy for this demanding application.
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