material EN 10058 EN 10089 - 56Si7 chemical composition tolerance

[Zaak]

Hi everyone, I have following question for help.

We have bought directly from manufacturer the flat steel strips in quality EN 10058 EN 10089 - 56Si7 with dimension 13x90mm L=6000mm each strip and in totally there were 40 strips.

After assembling and field work we have a break down of this strip (only 2 strips were broken). After checking the chemicals structure of the received goods in closest laboratory, we found out that there is one chemical that is out of specification when compared to Manufacturers certificate of quality.

According to manufacturers certificate C is 0,57
Our laboratory measured 0,539

Then we measured last year delivery and have following results:
manufacturers certificate shows C = 0,55
Our laboratory measured C = 0,401

Question is: is there any tolerance that is applied regarding this issues or given number in manufacturers certificate has to be the minimum that should be measured when checked.

What is you suggestion on this question, how to approach, thanks in advance

Zaak

 

[mrfailure]

56Si7 is specified to have carbon content of 0.52-0.60% with a carbon equivalency of at least 0.7 (important if this is welded). Only your lab measurement showed deficiency and no tolerance would make that number acceptable.