A method for manufacturing a non-superelastic file comprising the steps of:(i) providing a superelastic file having an austenite finish temperature； and(ii) heating at least a portion of the superelastic file to a temperature from 300 °C to 600 °C for a period of time from 5 minutes to 120 minutes to alter the austenite finish temperature thereby forming the non-superelastic file； wherein the altered austenite finish temperature of the non-superelastic file is from 20°C to 40°C；further comprising the step of(iii) cooling the portion of the non-superelastic file and(iv) heating at least a portion of the cooled non superelastic file to a temperature from 300 °C to 650 °C for a time period from 1 minute to 45 minute to shape-set the portion of the shaft thereby forming a shape-set non-superelastic nonlinear file.
