Crack in A485-1 ring during plug quenching
Crack in A485-1 ring during plug quenching
(OP)
I am facing quench cracking during plug hardening of ring with oil quench (`40C).
Hardening temp at 830C. Ring is transfered to plugging press and quenched with oil.
Material is A485-1, ring dia is 250mm and thickness is 23mm.
Crack always in the same location of undercut. Any reasons / solution ?
Hardening temp at 830C. Ring is transfered to plugging press and quenched with oil.
Material is A485-1, ring dia is 250mm and thickness is 23mm.
Crack always in the same location of undercut. Any reasons / solution ?





RE: Crack in A485-1 ring during plug quenching
"Even,if you are a minority of one, truth is the truth."
Mahatma Gandhi.
RE: Crack in A485-1 ring during plug quenching
RE: Crack in A485-1 ring during plug quenching
No decarb / recarb
Fine martensite
Grain size 8 or finer
No any segregation
No GBO / NMTP
Hardness - 64 HRc as quenched both core and surface.
RE: Crack in A485-1 ring during plug quenching
Is the quench die possibly restricting oil flow to the undercut surface?
RE: Crack in A485-1 ring during plug quenching
Quench die is not restricting the oil flow to the undercut. Undercut is open to oil.
I have shown a small sketch for understanding. And crack always on the top undercut area.
Die is a taper die which sits on both top and bottom bore. Oil flow is from both top and bottom.
RE: Crack in A485-1 ring during plug quenching
RE: Crack in A485-1 ring during plug quenching
In general quench cracks often occur where there is a significant local difference in heat transfer and cooling rate. The re-entrant profile of the grinding relief might be creating a separated recirculating local flow condition preventing the cool bulk oil flow from reaching the obscured undercut surfaces, thus inhibiting local heat transfer significantly. Also, the radial section is thick below the undercut, the flange above the undercut is even radially stiffer, and the narrow undercut groove between with its relatively small root radius provides a very effective local stress concentration.
Might be worth spending some time on modeling to optimize the cooling oil flows and heat transfer of your quench tooling.
RE: Crack in A485-1 ring during plug quenching
Thanks
RE: Crack in A485-1 ring during plug quenching
RE: Crack in A485-1 ring during plug quenching
What's your opinion on this?
RE: Crack in A485-1 ring during plug quenching
http://www.asminternational.org/web/edfas/technica...
Maui
RE: Crack in A485-1 ring during plug quenching
Maui
RE: Crack in A485-1 ring during plug quenching
Thanks again.
RE: Crack in A485-1 ring during plug quenching
What will happen if we take out the parts from quenching at slightly higer temperature (may be at 100C surface temperature instead of 50C).
So martensite formation in the core can be made uniform with the surface at the end.
Will this help.
RE: Crack in A485-1 ring during plug quenching
Maui
RE: Crack in A485-1 ring during plug quenching
Maui
RE: Crack in A485-1 ring during plug quenching
Do you suggest to reduce the oil flow and what is your recommendation.
Thanks
RE: Crack in A485-1 ring during plug quenching
Are you measuring the temperature of the parts as they come out of the quench? What is their average temperature?
Maui
RE: Crack in A485-1 ring during plug quenching
Quench time is 160 Sec.
Ok let me try with reduced flow rate.
RE: Crack in A485-1 ring during plug quenching
Oil flash point is 175 C is there any risk of fire because if the part surface is at 100C then the core may be at higher temperature.
So after some time the surface temp may increase and if it reaches 175 C it may fire.
Is this can happen ? Also part dimension may distort to some level.
Any other reason for not recommending this concept.?
THanks
RE: Crack in A485-1 ring during plug quenching
And yes, fire could also be a concern if you decide to do this.
Maui
RE: Crack in A485-1 ring during plug quenching
What were the results of your testing with the reduced oil flow rate? Did you implement any of the other recommendations?
Maui
RE: Crack in A485-1 ring during plug quenching
Reducing the oil flow did not help, upon further reduction we are getting NMTP.
Undercut design change not possible. Will update you all after further trials.
Thanks for all your ideas.
RE: Crack in A485-1 ring during plug quenching
Maui
RE: Crack in A485-1 ring during plug quenching
In quench press with out die only with quenching also it cracks.
RE: Crack in A485-1 ring during plug quenching
Look at the pressure of outer expander and if used, the inner expander of the press.
lower all pressure to the minimum.
what is the size of the id of the part and what is od of the plug quench. what is the diffrence in size.
also very little information on the heat treat cycle and temp's. is the oil slow or medium quench.
when ruff turning these parts is it possible to do a stress relief. or can this steel be normalize.
I could not find any data sheets on this stuff, if any one can supply that it would help.
what is the heat treat procedure, or what heat treat specification.
the press outer expander plate may be cracking the parts do to the configuration of the part.
pressing with to much pressure. with parts like this I want my supplier to use slow acting oil with the
highest oil temperture possible. as to not crack parts. if permissible.
so the term mar quench or martemper. but not as high.