In situ heating TEM observations of a novel microstructure evolution in a low carbon martensitic stainless steel

Abstract

A novel lath-shaped ω phase has been observed in the 0Cr13Ni4Mo low carbon martensitic stainless steel after quenching from high temperature, The orientation relationship is determined as: [011]α//[21¯1¯0]ω and (21¯1)α//(011¯0)ω. Using in situ heating transmission electron microscopy (TEM), we have investigated the microstructure evolution of the steel during heating. It has been found for the first time that the ω phase dissolves gradually during heating. Meanwhile, another newly identified nanometer scale λ phase precipitates homogeneously distribute within the martensite matrix. The λ phase precipitates have sizes of several nanometers and exhibit an orientation relationship with the matrix as follows: [011]α//[0001]λ and (2¯00)α//(12¯10)λ. The results are considered to contribute to a better understanding of the microstructure evolution of the martensitic steels during quenching and tempering.