|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||||||||||
|
|
|||||||||||||||||
May 13 - 16, 2008 |
|
 |
Extrusion/Die Practical 055 PR Gas Nitriding versus Ferritic Nitrocarburizing in Surface Hardening of Extrusion Dies George J. Tymowski, Achilles Nikopoulos -- Nitrex Metal Inc., Montreal, Canada Both nitriding technologies are used extensively to enhance wear resistance of extrusion dies. The referenced technologies differ in the type of the nitriding case configuration they produce. Controlled gas nitriding carried out at the low nitriding temperature range produces typically a very hard, wear resistant nitrided case with relatively low toughness levels. The controlled ferritic nitrocarburizing process (FNC) carried out at the higher end of the nitriding temperatures spectrum produces less hard and less wear resistant nitrided case. While high hardness/wear resistance at the die bearing may be the desirable effect of die nitriding, the inadequate die handling procedures, often leading to die flaking, frequently overshadow the benefits of good wear resistance. The different structure and stress distribution of the nitrocarburized case plays therefore an important role in overcoming one of the common die failure modes such as flaking and corner chipping in or around the bearing area of the die. |
