Effect of Small Amount of V, Ti and Zr Addition on Carbide Precipitation in Hadfield Steel Heated after Solution-Treatment

Study on austenitic high manganese st (eels. II)

Abstract

Small amounts of V, Ti and Zr addition of Hadfield steels were studied by micrography and dilatometry on isothermal carbide precipitations. By addition of these elements Hadfield steels precipitated carbides quickly and also enlarged the precipitation-temperature ranges. These effects were especially remarkable by addition of Ti or Zr, but the lower side of carbide precipitation line of steels migrated to a higher temprature side by addition of both of these elements. Thus, carbide precipitations at a low temperature range of Ti- or Zr-added steels were decreased than standard steel.
Acm temperature of steels were shifted to a higher temperature by addition of these elements, therefore solution-treatment temperatures of steels, added with these elements, required higher temperatures than the standard steel. Growth rates of pearlitic constituents in steels, added with Ti or Zr, were increased remarkably than that of the standard steel. When non-metallic inclusions were much present in steels, precipitation of pearlitic constituents in steels became quick, and it was presumed that increases of growth rates of pearlitic constituents by addition of Ti or Zr in steels were due to the presence of inclusions, especially nitrides in steels.
Yield strength of steels after solution treatment were improved by addition of each of three elements, without lowering of toughness, but mechanical properties of steels heated after solution-treatment, added with each of three elements, were lowered in a wide temperature range than the standard steel, because carbide precipitations were accelerated by addition of each elements and precipitation temperature ranges were enlarged than that of the standard steel.