Structure anomaly of thick case-hardened and hardened layers of tooth wheels

Skrbek Břetislav - TU Liberec (Czech Republic)

Expertise of big mating conical wheels with crumbled flanks of teeth. Material – EN 10084 18CrNiMo7-6 steel 1.6587; layer thickness 1,5 mm. Matrix of case hardened layer – mostly fine dark needles of low tempered martensite – contains structure anomalies of shape of coarse needles of martensite in bright field and network connecting with cracks propagation.

Metallography, scanning electron microscopy, fractography, local elemental analysis, courses of microhardness. Analysis of results – discussion. Definition of cause of failure of gear assembly function and recommendation.

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