Abstract
The effects of Si and Ti on the precipitation behavior of 14Cr-7Ni martensitic stainless steels during aging treatment have been investigated. Precipitates are examined by transmission electron microscopy, X-ray diffraction analysis and so on.
In the steels containing Ti only, the shape of precipitates in the matrix changes from fine particles to rodshaped as the aging stage proceeded from peak hardness to over-aging. The precipitates are iderntified as Ni3Ti, η phase. At an early stage of aging, predominant precipitations take place at grain boundaries.
On the other hand, in the steels containing Si and Ti in combination, fine spherical precipitates are formed uniformly in the matrix. They are identified as Ni16Ti6Si7(G-phase) and coherent to the matrix. It is suggested that the coherent strain induced by the precipitates hardens the steel remarkably.
