Carburizing of 8620 Material 1

[Butchie1946]

I have a question that someone can answer. I have an Engineering Drawing that requires Case Harden to 88.5-91.5 HR15N. It does not say anything
about what the Core Hardness should be. When you Carburize 8620 you could end up with a range of 25 to 45 HRC range in your Core Hardness numbers.
Should the I ask the customer what the Core Hardness should be? Looking for an answer.

 

[tbuelna]

Ideally, besides core hardness, your customer would also have provided explicit requirements for case depth, metallurgy, etc. By providing explicit requirements your customer minimizes the potential for conflict between you and them over the quality of the parts you deliver. In reality, it makes things easy for you as a vendor when a customer does not provide explicit QA requirements. But if this is a customer that you value, it would be a good idea to ask them to clarify the issue.

 

[dbooker630]

Core hardness is dependent on section size and hardenability of the base metal. As you have noted 8620 can have a wide range of hardnesses. You need to find out at what depth and location is the core hardness to be checked. Also need to find out if the case hardening is total case or effective case (e.g. 50 HRC, 50% martensite). Other aspects include allowable intergranular oxidation, retained austenite range. The customer should have their own process specifications that should be provided to you.