The increase in length of high silicon molybdenum ductile iron when it is cooled to room temperature after holding for a certain time at different operating temperatures is shown in Figure 6.It can be seen from the diagram that the length of high silicon molybdenum ductile iron varies with the working time at high temperature below 850 C.
The length growth rate is stable at about 0.044% after 40 hours working at 800 C. After 80 hours working at 850 C, the length growth is stable at about 0.062%, but when the temperature reaches 900 C, it experiences 100%.After one hour, the length increases to 0.134% and there is no tendency to stabilize at a fixed value, which also indicates that high silicon molybdenum ductile iron can not work continuously at 900 C.The abrupt increase in working time length between 60 and 70 hours at 900 C is attributed to the transformation of ferrite to austenite through the previous analysis.