Experience from 20CrMnTi
Experience from 20CrMnTi
(OP)
I have been proposed to use Chinese 20CrMnTi for a gear application. We have been using European material 34CrNiMo6 for a long time with good experience. The gears run only short times, but can be heavily overloaded due to the rough application. By changing material we expose ourselves to the danger that the new material is not durable enough. What is your experience with this material in your applications?





RE: Experience from 20CrMnTi
RE: Experience from 20CrMnTi
20CrMnTi China material
Rel 850 MPa
Rm 1100 MPa
HB 217
Elongation A[%] 10
Reduction of area R[%] 45
As I understand this is the base property without any Q and T after machining. If so this ought to be a good material. I have a memory that Rm and HB has a linear relation. Is this correct?
RE: Experience from 20CrMnTi
RE: Experience from 20CrMnTi
We have been having gear failure with gear and pinions of our small gear reducers (2083 ftlbs torque)using this 20CrMnTi but the larger gear boxs have not failed (38,000 ftlbs torque)
The design did not change only the steel and we have gearbox's still in service after 27 years of service with no wear to gears or bearings.
In my 23 years of design exp. I have always ordered my gear boxs for what ever application I needed but now I have to debug this one.
In my research I have found that ideally we would want a Casehardened Pinion running with an oil-treated Gear treated to a Brinell hardness in which the teeth may be cut after being treated negating the distortion and the pinion should be Casehardened after cutting and should be double quenched to refine and toughen the core, being relatively small, the distortion is minimal.
Pinion 57-61 Rc I think these are right.
Gear 30-40 Rc
With this combination it has been found that the harder pinion teeth correct the errors in the gear teeth to some extent by the initial wear and then seem to burnish or polish the teeth of the gear and increase its ability to withstand the wear by the greater hardness due to the cold working of the surface.
Are these statements true
RE: Experience from 20CrMnTi
RE: Experience from 20CrMnTi
We also spec less than 15% retained austenite.
The gears teeth seem to wear well but the bearing journals are starting to fail. The aplication for the gears is hydraulic gear pumps.
Does anyone have experience with the use of 20CrMnTi as a substitute for 8620?