22.2, uncharged specimens with a hardness even higher than H V=447 were fractured with plastic deformation after yielding. This fact implies that TiN inclusions in the uncharged specimens were cracked under plastic deformation in a tensile test because TiN inclusions cannot follow large plastic deformation of the matrix. 22.3a and b), fracture origins are TiN inclusions. In both cases of uncharged specimens ( Fig. These inclusions are typical ones contained in ordinary commercial bearing steels such as SAE52100.
Since Al and Ca were detected using EDX, the nonmetallic inclusions were identified to be Al 2O 3 22.3c and d shows a typical nonmetallic inclusion at a fracture origin of the H-precharged specimens. Since Ti and N were detected by EDX, the nonmetallic inclusions were identified to be TiN inclusions. 22.3a and b shows that the uncharged specimens also fractured from nonmetallic inclusions. Results for two levels of Vickers hardness, H V=678 and 559 are compared. The mating surfaces at the fracture origin are also shown in Fig. 22.3 compares the fracture surfaces of uncharged specimens and H-precharged specimens.
