heat treating CR C1050 Annealed steel

[denmen53]

I work for a steel service center and we have a customer who stamps all different types of automotive fasteners out of light gauge (.015-.055) CR C1050 ann steel.They stamp and heat treat in-house.
They have sent us failed parts and claim that they heat treated the parts based on the certification we supplied. We certified to a .52% carbon. It looks like the actual carbon content was .47-.48% carbon. Would this difference in carbon dictate a change in the heat treatment cycle. Does not the steel thickness play the major role in cycle time?
Thanks,
Bobby

 

[CoryPad]

denmen53,

This is more to heat treating than cycle time and part thickness. For example, carbon concentration must be matched between the part and the furnace atmosphere. Also, the lower carbon concentration means that the part will form less martensite upon quenching, which can affect the mechanical properties. So, your company is liable for providing parts that did not meet the certification.





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[stanweld]

Please provide info as to nature of failed parts and the heat treatment specified and given. It is possible that the heat treatment that was certified on 0.52% C material would need to be altered on 0.47-0.48 C material.