Gross Cracking is a catastrophic failure of a tool where the cracking is so severe and large that the integrity of the tool is challenged.  Often this type of failure is unrepairable and requires replacement of the tool.  Quite often it initiates at the water line or some area on the die that requires toughness.

Photos of Gross Cracking Examples

Incoming steel toughness measured by charpy impact testing and verification is sometimes missed by the end user, thinking that a premium grade H-13 steel or other hot work steel is assured to have the required toughness.  NADCA's spec 207-2006, however, calls out a minimum 10 ft lbs of charpy "v" notch strength.   Heat treat can improve or degrade the required properties of the steel and is a very important ingredient in getting proper micro structure, banding, etc...

NADCA Heat treat spec 207-2006 - order here from NADCA.

In the NADCA spec, charts are shown that grade the currently most used hot work types and show guidelines on proper heat treat procedures.  To preview some of these charts click on the below button.

Pdf of 207-2006 charts only

To summarize findings of NADCA's Die Material Committee (DMC), we have created a short 9 slide powerpoint presentation which can be viewed directly from our web site or downloaded for off line viewing.

This slide show will give a quick read on how to protect yourself from Gross Crack failures.

To navigate this slide show of 9 images
1. Click on the thumbnails (small images) from left to right.
2. Use the right and left arrows (clear) on the screen to scroll the slide images.