AN EM STUDY OF CARBIDE PRECIPITATES IN HK40 REFRACTORY STEEL

A thin foil electron microscopic study has been made of the various morphologies and microstructures of the carbides Cr_7C_3 and M_(23)C_6 in HK40 (4Cr25-Ni20) austenite casting steels The orientation relationship between the M_(23)C_6 precipitates and the austenite matrix during high temperature tempering has been identified by electron diffraction patterns The morphologies and Burgers vectors of the dislocations in the austcnite matrix, carbides and interfaces have been examined The weak beam and Moire pattern techniques have also been used in the analysis