ASTM A193 grade 8B Class 1 vs Class 2 stainless steel

[Prestressed Guy]

I have a project that had ASTM A193 grade 8B Class 2 stainless steel threaded rods specified for a concrete corbel repair but Class 1 was installed . The connection is now covered with grout with a beam on the corbel. My understanding is that the only difference between the class 1 & 2 is strain hardening. The rods are subjected to direct tension only.

Class 1 Fy = 30 ksi

​

Ftu = 75 ksi
Class 2 Fy = 100 ksi

​

Ftu = 125 ksi

What is involved with Strain Hardening and as the load on this corbel increases, will it in effect be "strain hardened"?

 

[EdStainless]

The higher strength fasteners have to be made from bar that has been cold worked to a specific level.
Your fasteners are only 60% of the required strength.
Good luck.
The party responsible for this mess up is on the hook for removal, repair, and refinishing.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

First, what specific Grade are you referring too in the ASTM A 193 material specification? A 193 provides various grades B7, B8.... with associated strength classes.

I think you meant Grade B8 with strain hardening during fabrication separating the two Classes.

If this is the case, you have a serious nonconformance with the Class 1 rods because they will not approach the strength level from strain hardening in service due to tightening. You should replace the Class 1 with Class 2, as originally specified.

 

[Prestressed Guy]

That is what I figured but thought it was worth a try. I find it interesting the difference in the Fy increase vs the Ftu increase with the strain hardening. Fy, 100/30 = 3.33 Ftu, 125/75 = 1.66

I may also look into F-593 CW1 or 2 as an alternate.