Influence of heat treatment on the microstructure, surface roughness and corrosion resistance of martensitic stainless steel

摘要

The effects of heat treatment on the microstructure,hardness uniformity, surface roughness and corrosion resistance Crl3 type martensitic stainless steel (MSS) were studied in this research.Metallography observationashow that martensite is the major phase in steel matrix, and as the tempering temperature reached 650 °C, ferrite became the main phase of MSSs, and the evolution of microstructure of MSS during different tempering could be concluded as tempered martensite→tempered sorbite.Hardness and surface roughness measurements reveal that the surface quality of MSS is highly affected by hardness, and the improvement in hardness uniformity can promote the surface roughness of the steel.After tempering, the corrosion resistance of the steels decreased, especially when tempering at 450 °C, the polarization curve of such heat treated steel showed no passivation regime, It turned out that the Cr-rich undissolved and tempering precipitatedcarbides existed in lower temperature (below 1130 °C) austenitized sample and such Cr-rich precipitates precipitating after 450 °C and 650 C are the main factor of decreasing the corrosion resistance of the stainless steels.