Failures in Aluminum Extrusion Dies

Aluminum extrusion dies undergo rigorous heat-treating cycles prior to service, followed by periodic surface treatments to maintain hardness. Hot-work tool steels, such as H13, require precise through-hardening to prevent decarburization, along with several tempering cycles to ensure stability at high extrusion temperatures. Vacuum hardening remains the most reliable method for achieving uniform hardness without surface defects. Furthermore, high-temperature tempering demands the use of vacuum or atmospheric furnaces that offer protective environments and superior thermal uniformity.

Unlike initial hardening, nitriding is a repetitive maintenance process to restore surface hardness between extrusion. Ideally, each cycle should produce an optimal nitrided case with a compressive stress distribution designed to minimize flaking and brittleness. This analysis provides an insight in causes of die failures stemming from materials defects, initial heat treating as well as subsequent nitriding cycles intended at extending die life and lowering tooling costs.