Concurrent Hardening and Toughening of a Tungsten Heavy Alloy via a Novel Carburizing Cyclic Heat Treatment

Tungsten heavy alloys (WHAs), due to the combination of some attractive properties, are used in many engineering applications. Recently conducted researches are however focused on improving the surface properties of these alloys, such as their hardness, wear, and corrosion resistance, by applying different surface treatments. However, the obtained enhanced surface properties are concomitant with the maintenance or even deterioration of the mechanical properties, namely toughness, in the interior regions of these alloys. Herein, a novel carburizing cyclic heat treatment (CCHT)-integrated technique is used to modify the microstructure of a 93W-4.9Ni-2.1Fe heavy alloy (93WHA). Other than investigating the effect of the applied process on the surface hardness and microstructure of this alloy, the influence of the conducted process on the microstructural and mechanical properties of the interior region of the processed parts is investigated. Due to the application of the CCHT process, the surface hardness of parts increases from 300 HV0.5, as observed in the nontreated samples, to the maximum value of 1049 HV0.5. In addition to the hardening effect observed on the surface of the treated samples, the interior regions of the CCHT-modified parts are toughened.