effective case depth of 31CrMoV9 nitriding workpiece

[peuray]

what's the maximum effective case depth of 31CrMoV9 nitriding workpiece U can achieve ? 0.75mm?
In most Eu&U.S wind generator gear with nitriding ,which widespread effective case depth did u choose? 0.5MM?
thanx everyone

 

[TVP]

There was an excellent article in the July 2007 issue of Gear Technology that discusses nitriding of large gears for wind turbines, etc. Typical nitriding depth (NHD) is in the range of 0.5-0.8 mm for a conventional nitriding steel like 31CrMoV9, but can be in the range of 1.2-1.4 mm for more heavily alloyed grades like Aubert + Duval's GKP (32CrMoV5). Use the following link for more information:

http://www.geartechnology.com/pa/members/july07/section5.pdf

 

[metengr]

Here is another excellent paper from Gear Technology

http://www.geartechnology.com/issues/0705x/hohn.pdf

 

[metengr]

peuray;
Not to confuse the issue but the reason I suggested the technical paper in my last post was that the wind turbine OEM gear boxes are a planetary gear design, and do not use nitriding for the planetary gears. The planetary gear set along with the low, intermediate and high speed pinion/gear sets use gas carburizing with great success.

The only time I have seen nitriding used was by one wind turbine OEM, and this was for the large ring gear.