10B22 hardenability

[Screwman]

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?

 

[CoryPad]

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:
[tt]
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
[/tt]

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Screwman]

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

 

[CoryPad]

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

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[TVP]

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.