This work is concerned with determining the effects of substituting W for Mo on mechanical properties in maraging steel.
Heats of Co-free maraging steel and W-bearing maraging steels were prepared by vacuum induction melting. The ingots were subjected to hot forging and rolling, followed by solution treatment and aging.
The testing of hardness, tensile properties, impact energy and low cycle fatigue properties the W-bearing and Co-free maraging steel were performed under both solution treated and maraged condition. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis were employed to observe the fracture surface of impact specimen and identify the composition of grain boundary precipitates.
It is found in this work that the yield stength of the 4.5% W-bearing alloy (231.4ksi) is about 9% higher than that of the Co-free maraging steel (228.2 ksi).
The impact energy of the 4.5% W-bearing alloy (12.9 ft-lbs) was about 30% higher than that of the Co-free maraging steel (9.8 ft-lbs).
Ti(C,N) or TiC was observed at the fracture surface of 4.5% W-bearing maraging steel and titanium sulfide was observed in case of Co-free maraging steel.
Total strain controlled L.C.F. tests were conducted using Instron servohydraulic test machine under maraged state.
It was observed in L.C.F. test that W-bearing maraging steel was more strong than Co-free maraging steel.
These work show that substituting 4.5% W for 3% Mo in Co-free maraging steel is possible in view of having good strength and fracture toughness.
