Influence of molybdenum alloying on thermomechanical fatigue life of compacted graphite irons

Abstract

In this study four compacted graphite irons (CGIs) and one grey cast iron (FGI) were produced and tested in the laboratory. The molybdenum content of the four CGI grades was varied between 0 and 1?01 wt-%. The purpose of the investigations was to examine the effect of the different molybdenum contents of the CGI on the thermomechanical fatigue (TMF) behaviour. The TMF tests were performed by cycling a constrained specimen between 110 and 600uC. For every material three tests were performed on specimens machined from a Ø20 mm cylinder. Other tests were performed on specimens machined from Ø55 mm and Ø85 mm cylinders respectively. The tests showed that additions of molybdenum improved the fatigue resistance of CGI. It was observed that additions of molybdenum refined the pearlite and that the specimens with a finer metallic matrix had a higher TMF resistance.

Stress relaxation of compacted graphite iron alloyed with molybdenum

“…1 The specimen had a gauge section of 12?7 mm in diameter by 51 mm long with a concentric 4?8 mm hole as shown in Fig. 3.…”

“…1 2 Geometry of castings 1 Typical stress relaxation curves 6 3 Geometry of specimen 4 Value of compressive stress against time for all examined materials: maintaining temperature is 600uC…”