hrvatski

Ustanovljenje parametara toplinske obrade odljevaka od legiranog čeličnog lijeva otpornog na trošenje

The effects of tempering temperatures on microstructural and mechanical properties of in oil quenched low-alloyed Cr-Ni-Mo cast steel intended for wear resistant tool have been studied. In as-quenched condition an inhomogeneous martenzite microstructure with about 10% retained austenite was achieved, which have had average tensile strength 1442 MPa and hardness 53 HRc. Tempering og oil quenched steel samples was performed in 400 to 700 °C temperature interval. Heat induced martenzite destabilization and carbide precipitations resulted by linear decrease tensile strength from 1600 to 800 MPa and yield strength from 1400 to 600 MPa, as well as by instantaneous increase of elongation end contraction from 5 to 20 % and 10 to 50 % respectively. Microstructural changes with increasing of tempering temperatures were also followed by average decrease of hardness from 45 to 22 HRc as well as simultaneously, gradually increase of toughness from 10 to 70 J. The obtained results made possible to define optimal heat treating parameters and to achieve good combination of tougness and hardness in real wear resistant castings.

parametri toplinske obrade; čelični lijev otporan na trošenje

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