Rapid Screening of the Mechanical Properties of 13 wt%Cr Steels with Uncharted Combinations of C and N Contents

Abstract

Stainless steels containing both C and N have unique characteristics while requiring unconventional manufacturing methods. This latter feature also translates into a lack of systematic investigations into their properties. In this work, a series of 13 wt%Cr steels with various interstitial solid solutions of C and N was synthesized by high temperature solution nitriding, HTSN, of commercial 13 wt%Cr martensitic steels. Light optical microscopy was applied to reveal the microstructural features, which consisted of a combination of martensite and austenite in various ratios depending on the C and N content. The mechanical response was characterized by nanoindentation. Data analysis assumed a fixed hardening exponent and provided an estimate of the yield strength and Young’s modulus of the synthesized steels and their microstructural components. The comparison with literature data indicated that this estimate is sound for martensite, while the data for austenite suggests an underestimation of the hardening exponent for this phase. The investigation demonstrates the potential of HTSN for the synthesis of novel 13 wt%Cr steels alloyed with both C and N. Moreover, it suggests that the use of nanoindentation for extracting the mechanical properties is limited by the non-uniqueness of the method with regard to the hardening exponent.