The relationship of hot and cold rolling processes with the structure and properties of invar 36

Invar 36 with both high hardness and low coefficient of thermal expansion (CTE) is desired in aerospace, defense, aviation and electronics industries. In this study, 20% cold rolling and 50% hot rolling processes were applied to the commercial invar 36 without adding any other alloying elements. In the cold rolling process, martensitic transformation was not observed due to the high stacking fault energy of invar 36. The (220) intensity decreases with hot rolling under the recrystallization effect, while it increases with cold rolling. While the average grain size was 300 mu m as-casting, it was reduced to about 50 mu m by hot rolling. The lowest CTE value was obtained in the cold rolled sample as 0.331 x 10-6/degrees C. The Curie temperature was found to be approximately 185 degrees C by differential scanning calorimetry (DSC) analysis. There was no significant change in microhardness of as-cast and hot rolled samples. The maximum microhardness is 220.1 HV5 in the cold rolled sample.