M. D. Hanna, GM Reserach and Development Center, Warren, MI; J. G. Schroth, GM Research and Development Center, Warren, MI
Forming of aluminum at elevated temperatures requires wear-resistant tool surfaces. The effects of nitrocarburizing temperature and time on the compound layers developed on different low and medium carbon tool steels for use in high temperature forming processes were investigated. The surface layers were analyzed by optical and scanning electron microscopy, microhardness measurements, and X-ray techniques. AISI P20 tool steel was found to be suitable for nitrocaruburization and for use as an elevated temperature tool material due to its relative stability and durability, its availability in large block sizes, and also its functional properties in the forming environment. A non destructive method of relating the hardness of the nitrocarburized AISI P20 steel tool surface with the depth of the compound layer was used to evaluate tool durability with time to provide a means to monitor and estimate the compound layer thickness in the plant environment. The method can be used to establish tool maintenance and refurbishment procedures.
Summary: Forming of aluminum at elevated temperatures requires wear-resistant tool surfaces. The effects of nitrocarburizing temperature and time on the compound layers developed on different low and medium carbon tool steels for use in high temperature forming processes were investigated. The surface layers were analyzed by optical and scanning electron microscopy, microhardness measurements, and X-ray techniques. AISI P20 tool steel was found to be suitable for nitrocaruburization and for use as an elevated temperature tool material due to its relative stability and durability, its availability in large block sizes, and also its functional properties in the forming environment. A non destructive method of relating the hardness of the nitrocarburized AISI P20 steel tool surface with the depth of the compound layer was used to evaluate tool durability with time to provide a means to monitor and estimate the compound layer thickness in the plant environment. The method can be used to establish tool maintenance and refurbishment procedures.
