Cracking problem

[Throwingsteel]

hello all, I am having a problem of cracking in 4140. I am induction hardening and tempering. I am having small crack develop along the parting line showing up under magnaflux. The draw temperature is 550 for 2 hours. Is temper embrittlement any issue? I am racking my brain on why we are seeing cracks.

 

[inductionexpert]

22% is really high, usually not more than 15%, likely for this should be less than 10%. Suprised you get such high hardness with such high % of polymer.

Not grinding crack unless burning and you would see.

Leaving in temper at longer time will make no difference, need high oven temp, add 25F.This will not prevent the cracking, something else is causing.

Fred Specht
Ajax TOCCO Magnethermic
847-606-9462

 

[Throwingsteel]

the manufactueres spec is between 25-35 % concentration for 4140/4340. could too much concentration cause a problem?

 

[inductionexpert]

20% seems high,

last months "Forging" magazine had an article, just up your ally. "Defects in Hot forgings" by H.J. Henning. You must read @

http://www.forgingmagazine.com

on page 21.