Employed by optical microscope, scanning electron microscope, microhardness tester and X ray diffraction instrument, the isothermal decomposition process of high nitrogen austenite was investigated.

Optical metallographic microscope, micro-hardness tester, electron microprobe and X-ray diffraction analysis were applied to explore the process of intermediate temperature tempering transformation.

Macro examination, metallographic microscope, microhardness tester and X ray diffractometer were utilized to study the failure reasons for connecting rode bearing bush of automobile engine.