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10B22 hardenability

10B22 hardenability

10B22 hardenability

(OP)
I have an application where one of our plants wants to switch a 1.5 inch diameter bar from 4140 to 10B22.  The part needs to be heat treated to Rc 33-38 after tempering.  I am concerned that the 10B22 won't fully harden in that diameter.  My question is how large of a diameter bar will quench out fully hard in 10B22?

RE: 10B22 hardenability

SAE J429 allows boron alloyed low carbon steel to be used to produce parts up to 1 inch in nominal diameter for Grade 8.2 (hardness 33 HRC to 39 HRC).

The ASM Handbook Volume 1 lists the following:

          Largest size to quench to 42 HRC in center
Alloy     oil           water
-----     ---------------------------
4140      1.75 inches   2.4 inches

10B21     0.2 inches    0.7 inches

Regards,

Cory

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RE: 10B22 hardenability

(OP)
Hey Cory,
Thanks! Do you have any info on 40B37?  That is the new idea that they came up with now.

RE: 10B22 hardenability

No, I don't have any information for that.  40B37 should be able to meet your requirements.

Regards,

Cory

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RE: 10B22 hardenability

I agree with CoryPad that 40B37 should be able to quench to > 90% martensite (typical requirement for grade 10.9 fasteners) for a 1.5 inch section.  I may have some data for 4037 at my office (at home today), but I won't have anything for 40B37 since it is not a standard grade.  You should be able to obtain this type of data from a metallurgist at your fastener supplier, provided that they have one.  I would not make this change if this is being purchased through a distributor, if there is not a robust system for testing and engineering approval, etc.

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