Preheating before carburising process 1

[metalht]

Hi,

can tell me any one, why pre heating required before carburising process.

pre heating helps to control the microstructure (grains).

 

[CoryPad]

Pre-heating frequently is used to avoid losing all the heat in the carburizing furnace (which is > 900 degrees C) when you open the door and put in a large mass of parts and fixturing that is at room temperature.

 

[blacksmith37]

Not much affect for thick case like 40 mils, but if you want a thin case like 5 - 8 mils it is necessary.

 

[metalht]

Thanks for your reply. iam using 3mm case depth and controlled heating followed (+2 degree/min).
pre heating required for the above process

 

[TVP]

How big is this part (dimensions and mass)? Are there thick-to-thin transitions? Another reason to pre-heat is to achieve temperature uniformity through the different cross-sections.