Influence of initial heat treatment on microstructure evolution and mechanical properties during cold rolling and annealing of Hastelloy X

In order to study the influence of initial heat treatment on the microstructure and properties of Hastelloy X alloy in the subsequent cold rolling and annealing process, and to provide a research basis for the reasonable selection of parameters (temperature and time) in actual industrial production, specimens with three different initial heat treatment states (1040 degrees C/30 min, 1180 degrees C/5 min and 1180 degrees C/30 min) were selected and these specimens were cold rolled with a reduction of 50% and annealed at 1080 degrees C. The grain structure and carbides in the alloy were analyzed using a method combined with microscopic observation and quantitative statistics. A series of room temperature tensile and hardness tests were performed on the annealed alloys. The study found that the fundamental factor affecting the microstructure and properties of Hastelloy X alloy is carbides. The size, volume fraction and distribution of carbides directly affect the grain structure and mechanical properties. By choosing a lower initial heat treatment temperature (1040 degrees C) and a shorter time (5 min), the uniformity of grain size and carbide distribution in the annealed microstructure can be effectively improved. However, it should be noted that lowering the heat treatment temperature will also result in larger carbide size (0.275 mu m) and lower yield strength (400 MPa). In addition, this work also studied the effect of annealing time and found that it has the same effect as the initial heat treatment time.