In situ temperature measurement during spray forming of A2-tool steel and axisymmetric two-dimensional analysis

An in situ temperature measurement was performed during spraying of A2-tool steel, and the results were used to verify an axisymmetric two-dimensional computer simulation program, which was developed for the prediction of sha pe and temperature variation in a spray-forming process. A thin thermocoupl e was placed inside of the chamber in advance and brought to the surface of the deposit during spraying. The temperature was then recorded. The surfac e temperature of the deposit was also measured by an infrared video camera. The emissivity of the surface of A2-tool steel during spraying was determi ned to be 0.23 through comparison of the temperatures measured by the therm ocouple with the ones measured by the infrared video camera. The heat trans fer coefficient at the top surface was estimated by comparing the calculate d results with the experimental data. The cooling curve predicted on the ba sis of the numerical simulation showed good agreement with the experimental data.