2020 年 61 巻 7 号 p. 1220-1229
To create a new surface with desired microstructural features, the proportion of constituent phases and grain size should be quantitatively characterized. However, it is difficult for titanium alloy due to its adhesion microstructure. In the present study, a novel image processing method was proposed to characterize the microstructure feature of titanium alloy Ti–6Al–4V. Graham scan algorithm is innovatively applied to identify and separate the isolated and adhesive phases. Using the proposed method, the changes of volume fraction and grain size of beta phases induced by peripheral milling are evaluated. The main conclusions are as follows: the isolated and adhesive phases in SEM images of Ti–6Al–4V are well separated, and the correct recognition rate can reach more than 90%. The total volume fraction of the beta phase on the machined surface is larger than that of the original material, and its value increased with the increase of cutting speed. With the cutting speed increases, the content of isolated beta phase decreases but that of adhesive beta phase increases. Length-diameter ratio of the isolated beta phase induced by machining does not change significantly relative to that of the original material, which values are lies in the range of 1.9 to 2.0.
