Microalloying effects on microstructure and mechanical properties of 18Cr-2Mo ferritic stainless steel heavy plates
The microstructure, including grain size and precipitation, tensile strength and Charpy impact toughness of (Nb. +. V) 18Cr-2Mo ferritic stainless steel heavy plates with/without Ti were investigated by means of optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and standard tensile strength and Charpy impact toughness testing. It was found that for 18Cr-2Mo heavy plate, a good combination of Nb-V stabilized method without Ti induces refinement of grain sizes due to the precipitation of amounts of fine Nb carbonitrides and V nitrides. Meanwhile, the mechanical testing results indicate that optimal transformation of grain size, precipitation that Nb-V composition system brings to 18Cr-2Mo heavy plate is beneficial to improvement of strength and impact toughness.