Difference between ASTM A453 660 Class A, B and C 1

[EternalD]

Dear All,

I have been trying to research regarding the differences between these three classes but to no avail, could anyone kindly help to let me know if there are any physical differences and if they are interchangeable in their uses?

Thanks.
Keith

 

[metengr]

According to literature I have, the A 286 material has 3 options for heat treatment; the Class A solution treatment at 1650 deg F and subsequent age hardening is for optimum short-time tensile properties, and is within the range of mechanical properties per the ASTM specification.

The 1800 deg F solution treatment is for optimum stress rupture properties with Class B for liquid quench, and Class C for oil quench, which depends on section thickness hardenability.

Class A is desired for service conditions where short-time tensile properties are important at ambient to moderate temperatures. Class B and C are interchangable for elevated temperature service (stress rupture) because you are only dealing with different cooling mediums for optimum hardnability, prior to age hardening.

All three classes meet tensile properties as published, but they are not all interchangeable, it depends on service conditions.

Source: Materials Data Handbook on A 286

 

[EternalD]

Dear Metangr,

Thank you very much for your reply.

Just a further question,i would need to clarify your response, Class A is desired for service conditions where short-time tensile properties are important at ambient to moderate temperatures. Class B and C are interchangable for elevated temperature service (stress rupture) because you are only dealing with different cooling mediums for optimum hardnability, prior to age hardening.

Assuming we do not know the condition the customer is using the bolts in, could we assume they are interchangeable from stress rapture and the tensile strength alone?

Thanks
Keith.

 

[metengr]

My question back to you is what is the customer requesting? If they allow the use of any of the three Grades, fine. If they are requesting a specific Grade, like Grade A, you need to comply. Grades B or C can be interchangeable depending on section thickness, which dictates the severity of the quenching medium.

 

[EternalD]

Dear Metengr,

The customer just listed 660 A and 660 B. In this case, we wont be able to counter offer B for A or vice versa?
In addition, what is the limit for section thickness that allows grade b and c to be swap?


Thanks

 

[metengr]

KeithKoh
Supply them with Grade 660 Class A and Class B in the specific quantities they need. Regarding Class C, this would depend on heat treatment capabilities in terms of quenching. Without further information and testing, I would supply them Grade 660 Class B.