Carburizing 4140 to 0.250" 380 Brinell

[zonian1903]

Hi,
I am doing a little work for a project I am helping with where there is a requirement to harden one face of a 1.500" thick 4140 plate to a hardness of 380 Brinell and a depth of .250" (I didn't come up with this requirement). The are no places anywhere close by (I live in central America), where I could have this done, and haveing the plates treated in the states and shipped back would be cost prohibitive, plus we would like to be able to do this ourselves and learn in the process. Can someone recommend some reading on this? So far, through google, I've been able to figure out that most industrial gas processes are out of our means, and that I'm probably have to use a molten cyanide salt method and that there is a product called Kasenit which may work and seems to be very easy to use. Can Kasenit or molten cyanide salt reach the hardness and depths specified in the requirement? I really appreciate any help.

Thanks,
Francisco Perez

 

[adyonel]

Just quench at 1580F in oil and temper at 860F. The entire part will be at 380 Brinell.

 

[metengr]

Depending on service duty, thru-hardening may not be optimum. You need to carefully review the application of this part.

There are plenty of web sites on heat treatment of steels (surface and thru-hardening).

 

[adyonel]

but 4140 is not suitable for carburising and 380 Brinell is too low for an surface treatment.

 

[metengr]

Yes, I was thinking more along the lines of surface hardening by induction or flame heating, quenching in oil and subsequent temper to achieve the surface hardness of 380 BHN.

 

[adyonel]

Yes, but maybe we think too far. Zonian1903 can elucidate this issue.