tempering en 19 shafts

[thejackal3]

Dear all
we manufacture rock shaft for tractors. material EN 19 with hardened n tempered with hardness 30 -35 HRC.after finishing we have to do induction hardening the splines and required case hardness 45-50 HRC depth.after induction hardening quench hardness is 57 on the center spline and on both side spline quench hardness is 53 hrc,how much time should be keep for tempering to achieve 45- 50 hrc on both the spline and center spline as well.
regards

 

[redpicker]

The tempering time will depend on how your are heating the shaft for tempering and your tempering temperature. If you are going to be tempering in a furnace, then the shaft size will also be a factor.

For furnace tempering, one rule of thumb that is often used in one hour per inch of thickness, once the furnace has recovered to the set-point. This may need to be adjusted, depending on how the furnace is loaded and furnace capacity. As the tempering temperature should be well below the temperature used to obtain the 30-35 HRC core hardness, this second tempering operation should not affect the core hardness.

rp

 

[TVP]

If you need to have the hardness between 45 and 50 HRC, you can temper in the range of 370-425 C (700-800 F). The data that I have shows hardness of 429 HB (45 HRC) with tempering at 425 C (800 F). Tempering at 370 C should produce hardness of ~ 461 HB (~ 48 HRC).

 

[thejackal3]

thanks for the valuable insight. Dear TVP kindly suggest how much time should we give at 370-425 C (700-800 F) to attain hardenss between 45 - 50 hrc.
thanks n regards

 

[thejackal3]

thanks for the valuable insight. Dear TVP kindly suggest how much time should we give at 370-425 C (700-800 F) to attain hardenss between 45 - 50 hrc.
thanks n regards

 

[slashragnarok]

Please refer Table 34 of page 147. The section size would also matter.

https://books.google.co.in/books?id...AEwBg#v=onepage&q=4140 heat treat asm&f=false

 

[TVP]

thejackal3,

redpicker gave you the suggested value: one hour for every inch (25 mm) of section thickness.