Effects of processing parameters on creep behavior of 316L stainless steel produced using selective laser melting

Abstract

The selective laser melting (SLM) method is being increasingly applied in the aerospace and power industries for the production of high temperature critical components. The effects of SLM processing parameters, such as laser power, scanning speed, and energy density on the creep properties were investigated for 316L stainless steel (SS316L). The effect of building direction was also studied. The creep resistance was influenced by the manufacturing direction. The vertical specimen demonstrated a longer creep life and higher creep resistance than the horizontal specimen. The creep resistance remained constant when the energy density was kept constant during manufacturing. If insufficient energy density was used for manufacturing, internal defects, such as voids and unmelt powder were generated, and lowered the creep resistance. However, if sufficient energy density higher than a minimum value was employed, the material creep properties mainly depended on the level of the energy density.

A critical review on the effects of process-induced porosity on the mechanical properties of alloys fabricated by laser powder bed fusion

“…For instance, it is uncertain how the overall porosity level can affect creep life and whether there is a certain threshold where microstructural features can dominate over the porosity level. One example would be a study like the one on LPBF 316L by Bae et al as shown in Fig . 37 [157]. The authors found that the creep behavior was closely related to the density of the sample tested.…”

“…As can be observed in the table, growth and coalescence of pores are often responsible for creep failure [155,156]. Additionally, pores can also act as crack initiation sites that lead to premature creep fracture [155,157]. For example, Xu et al investigated the effect of heat treatment (homogenization, solution treatment and single-ageing) and surface finish on creep behavior of LPBF IN718 at 750 MPa and 650 °C, and found that while cracks often originate from the surface (with pre-existing cracks also caused by machining), porosity in the material can grow, coalescence and eventually lead to the fracture of the cross-section as illustrated in Fig.…”

“…Samples B02, B03, B04, B05 and B06 had densities of 7.88, 7.88, 7.85, 7.82 and 7.60 g/cm3 , respectively. Reproduced with permission from[157] (Copyright 2021, Springer Nature) where the authors investigated the effects of different LPBF parameters on the creep behavior of LPBF 316L parts.…”

The Characterization of Fatigue Damage of 316L Stainless Steel Parts Formed by Selective Laser Melting with Harmonic Generation Technique

“…The results are shown in Figure 7. Although the materials and the SLM processing parameters of the three specimens were the same, the normalized nonlinear coefficients always fluctuated at a certain level; the primary reason for this fluctuation is that the microstructure of tested specimens presented typical anisotropic characteristics [31][32][33][34]. Due to a high-energy laser beam being used as a mobile heat source during the process of the formation of the 316L stainless steel specimen using SLM technology, and through rapid heating, melting, and solidification, extreme non-equilibrium conditions were produced during the material's processing.…”