Abstract: Taking nitrocarburizing atmosphere as the research object, hydrogen sensor with oxygen probe and laser nitrogen potential sensor measure methods of K_N and K_C were introduced, and the influence of K_N and K_C on composition and structure of white layer in nitrocarburizing process was explained. The results show that the laser nitrogen potential measurement and control system can simultaneously measure and calculate the K_N and K_C of the nitrocarburizing atmosphere, and even if the gas ratio changing during the process do not effect the measurement of K_N.

Key words: nitrocarburizing, laser nitrogen potential sensor, K_N, K_C, SPCC steel, porosity