TEMPERED MARTENSITE EMBRITTLEMENT - TME I N 3CR-MO-V STEEL

The paper deals with the tempered martensite embrittlement phenomenon in the low-carbon low alloy 3Cr-Mo-V steel tempered in the temperature range of 200-500 degrees C. To determine the tempered martensite embr ittlement the Charpy-V test at the temperature -50 degrees C was perfo rmed. The methods of light mickroscopy transmission electron microscop y (TEM) scanning electron microscopy (SEM) and hardness testing (HRC) were applied. In failure energy temperature dependence the minimum at 350 degrees C was found to exist. The mechanism of transgranular cleav age corresponding to a transgranular mode of the tempered martensite e mbrittlement was found put during the failure. In the microstructure o f the quenched states the retained austenite around the martensitic la ths as well as the fine carbide particles inside the laths were observ ed. This can be considered as a cause of the transgranular mode of the tempered martensite embrittlement. The difference in grain size (0.1- 0.8 mm) affects the tempered martensite embrittlement of steel only we akly.