Please Note:
First measurment was on 4904-sandblasted
4904-oxidized was measured on the same samples
The holes for the TC where drilled just to the center of the samples and where 2mm Diameter
The holes where filled with Sika FireStop after inserting the TC
 
Composition of the 4904:
C:      0.06-0.09%
Si:     max.0.05%
Mn:     1.20-1.30%
Cr:     max.0.20%
Pb:     0.20-0.35% (normaly around 0.22%)