Abstract:

Additively manufactured 13Cr10Ni1.7Mo2Al0.4Mn0.4Si maraging stainless steel, also known as CX material, is a high-strength, high-toughness alloy that is a potential and economical candidate to be used in aerospace and defence applications to replace more expensive alloys, e.g., Ti–6Al–4V. One common way to improve the mechanical properties of as-built CX material is through the post heat treatment processes after manufacturing; specifically solution annealing at high temperature followed by aging for a couple of hours, like our previous research on this material [1]. Although significant improvement in mechanical properties achieved via this treatment it is not still a sustainable and energy-efficient way. Hence, this study is focusing on a novel heat treatment to shorten the heat treatment duration. For this purpose, first, the studied materials were additively manufactured by a laser powder bed fusion (L-PBF) method and then subjected to rapid annealing at 950 °C followed by rapid tempering at 675 °C using the Gleeble 3800 machine. Both heating and cooling rates were around 10°C/s. The applied thermal cycle is presented in Figure 1(a). The results showed that the rapid annealing followed by rapid tempering increased the yield strength and tensile strength of the as-built material, while the tensile ductility slightly decreased. According to the dilatometry result (Figure 1(b)) and microstructure characterization, the heat-treated sample samples mainly consisted of refined and homogenized tempered martensite with the fine carbide precipitates which is likely a contributing factor to the improved mechanical properties. This heat treatment shows a potential way to improve the mechanical properties of CX material for more cost-efficient industrial applications.

Figure 1. a) The thermal cycle of material using the Gleeble 3800 thermomechanical simulator machine, b) the dilatometry results related to the different steps of applied heat treatment.

References

[1] S. Afkhami, V. Javaheri, E. Dabiri, H. Piili, T. Bjork; Materials Science & Engineering A, 2022, 832, 142402