| Currently in development characteristics of materials to be many innovations made, among others, to increase strength, hardness, and micro structure changes. One way is with a characteristic improvement of cryogenic treatment. cryogenic treatment performed using liquid nitrogen media with low temperatures. The utilization of low temperature is performed to convert into phases martensit. This research was conducted on the final project aims to determine the influence of cryogenic treatment on steel JIS G4103 SNCM 439. This type of research is research done today. How to penyaesaian the research is by way of comparing the results of maximum tensile stress, violence, and value future modifications of micro structure before and after treatment occur conducted cryogenic tensile strain increases to a maximum of 1.67%, increase in the value of violence 1.89%, and micro structure changes. |