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 / / [ 2 1 ¯ 1 ¯ 0 ] ω  and ( 2 1 ¯ 1 ) α / / ( 01 1 ¯ 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 / / ( 1 2 ¯ 10 ) λ . The results are considered to contribute to a better understanding of the microstructure evolution of the martensitic steels during quenching and tempering.