Fractography analysis of tool samples used for cold forging

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    Three fractured tool dies used for industrial cold forging have been investigated
    using light optical microscopy and scanning electron microscopy. Two of the specimens were produced using the traditional Böhler P/M steel grade s790, while the last specimen was a third generation P/M steel produced using new technology developed by Böhler. All three steels have the same nominal composition of alloying elements.

    The failure in both types of material occurs as a crack formation at a notch inside of the tool. Generally the cold forging dies constructed in third generation steels have a longer lifetime than the ones constructed in traditional steel, which is connected to differences in microstructure. Focus has been put on differences in the size and distribution of carbides. It is found that the third generation steel contains smaller and more finely dispersed carbides and has an increased resistance towards abrasive wear compared with the traditional P/M steel.

    It was discovered that a cleaning agent (Alconox) frequently used for the cleaning of fracture surfaces introduced changes to the surface morphology. Therefore work was put into finding out exactly how this influenced the specimens looked upon. The result of this work is included as a separate part of this document (Appendix A).
    Original languageEnglish
    Place of PublicationRoskilde
    PublisherRisø National Laboratory
    Number of pages52
    ISBN (Print)87-550-3104-8
    ISBN (Electronic)87-550-3104-8
    Publication statusPublished - 2002
    SeriesDenmark. Forskningscenter Risoe. Risoe-R


    • Risø-R-1359
    • Risø-R-1359(EN)

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