Abstract: The influence of solid-solution temperature on hardness, grain size and precipitate behavior was investigated in order to obtain the definite range of the solid-solution process. It is shown that the solid-solution temperature has a relatively obvious effect on the hardness, a great effect on the grain size in Inconel690 alloy. When the temperature is over 10701, the grain size increases remarkably. The theoretical computation and SEM show that (Fe,Cr,Ni)₂₃C₆ carbide in Inconel690 dissolves completely at temperatures of 1070-1 090 ℃.