浸炭および高周波焼入れ歯車の曲げ疲労・衝撃強度(基調講演2)

抄録

The hardness of hardened layer was measured for various case-carburized and induction hardened spur gears, and effective case depths of gears were obtained. The intergranular oxidation generated near the tooth surface of the gear by gas carburizing was observed with SEM, and then amounts of intergranular oxidation were obtained. The bending fatigue tests and the impact tests were carried out for these case-carburized and induction hardened gears, and then bending fatigue limits and impact breaking energies were obtained. On the basis of these obtained results, effects of carburized part, case depth, face width, intergranular oxidation and tempering on the bending fatigue and impact strength of the case-carburized gear were clarified. Effects of the heating condition (electric power, frequency, heating time) on hardened depth, microstructure and profiles of hardened layer of induction hardened gears, effects of heating condition, surface hardness, hardened depth, pre-treatment (as-rolling, thermal refining), material (S35C, S45C) and tempering on bending fatigue and impact strength of induction hardened gears were determined. Furthermore, the bending fatigue limits and impact breaking energies of case-carburized gears were compared with those of induction hardened gears.