Homogenizing Treatment of AISI 420 Stainless and AISI 8620 Steels

In the present work, rocker arm low AISI 8620 and needle-nose pliers martensitic stainless AISI 420 steelsAISI 420 steel, obtained from melting and gravity casting processes, were analyzed during the homogenizing treatment. The as-cast steelAs-cast steel homogenizing specimens were microstructural and mechanically characterized by optical microscope, scanning electron microscope, and hardness test. In the case of AISI 8620 steelAISI 8620 steel, the observed microstructure was ferrite and carbides with a hardness of 26 HRC. In contrast, the observed microstructure was ferrite and two types of carbides with a hardness of 52 HRC for the AISI 420 steelAISI 420 steel. Both steel specimens were homogenized in the austenite region. The homogenizing temperature was determined using the Thermo-CalcThermo-calc calculated equilibrium pseudobinary phase diagrams. The homogenizing time was obtained by Dictra software. The homogenizing temperature and time were 900 °C and 8 × 104 s (22 h), respectively, for the AISI 8620 steelAISI 8620 steel, and 1040 °C and 7 × 104 s (19 h), respectively, for the AISI 420 steelAISI 420 steel. The results showed that the homogenized microstructure was ferrite, cementite (pearlite), and M23C6 carbides with a hardness of 88 HRB for AISI 8620 steelAISI 8620 steel, and ferrite and M23C6 carbides with a hardness of 43 HRC for AISI 420 steelAISI 420 steel.