Variations in Reported Values of the CTE This table gives the CTE for AISI 1050 steel taken from three different sources. The CTE has been converted to ppm/°C, and the temperature ranges to °C as needed. Obviously the CTE changes with temperature, and this leads to different "average" values over different temperature ranges. Of course even the word "average" may be defined differently by the three sources. The question is now, what is the CTE at 20 °C? This particular example is one for which multiple, seemingly independent sources exist. For most gages we do not even have this much information. | Reference | CTE | T-Range | CTE | T-Range | CTE | T-Range | | 1 | 14.6 | 21-650 | | | | | | 2 | 11.5 | 20-100 | 13.5 | 25-200 | | | | 3 | 11.2 | 0-100 | 12.1 | 0-200 | 13.5 | 0-400 | | 
