Functionally Graded AISI 316L and AISI H13 Manufactured by L-DED for Die and Mould Applications

Abstract

Tooling in the die and mould industry is subjected to high-wear and high-temperature environments, which often leads to the premature failure of this high-added-value tooling. When severe damage occurs, an alternative to replacing the whole component consists of the repair by laser-directed energy deposition (L-DED). For that end, intermediate layers are commonly employed as buffer material, where introducing a functionally graded material (FGM) might be beneficial to avoid material incompatibilities and improve the overall performance of the tooling. In the present work, an FGM composed of gradient AISI 316L to AISI H13 has been manufactured, and its microstructure and hardness analysed. Firstly, cracking owing to the formation of brittle intermediate phases has been detected. Secondly, an increase of the hardness and a decrease of the corrosion resistance has been observed when transitioning from AISI 316L to AISI H13. Thirdly, despite the FGM composition evolving linearly, nonlinear material properties such as hardness and corrosion have been observed, which are conditioned by the microstructure formed during the L‑DED process and the nonlinear influence of the composition of steel on such properties. Consequently, nonlinear compositional gradients are recommended if linear mechanical properties are to be obtained in the case of steel FGMs.

Material efficient production of functionally graded materials using coaxial laser double-wire directed energy deposition

“…The course of the hardness values indicates that a linear transition from material A to material B is not necessarily accompanied by a linear change in the hardness progression. This finding has been observed in the work of Ostoloza et al [1] and can be attributed to the formation of different microstructures due to the change in alloy composition along the course of the weld seam. For a simplified prediction of the microstructures, Schaeffler diagrams can be considered that relate the formation of the microstructures to the Cr-and Ni-equivalents of the weld materials.…”

“…One approach to minimize those stress maxima are Functionally Graded Materials (FGM). FGMs are gaining an increased attention across various industrial application fields, ranging from the die casting industry [1][2][3] to the aerospace industry as just some examples to be mentioned. The graded transition zone is intended to reduce the occurring stress maxima by generating a smooth transition between one material and another.…”

The potential use of laser cladded functionally graded materials to mitigate degradation in boiler tube heat exchangers for power plant applications: A review

“…Due to some intrinsic process defects, such as porosity, Figure 35. Variation of hardness in functionally graded AISI 316L and AISI H13 attributed to variation in composition [155].…”

“…Composition & powder flow rate The changes in material composition as the powders varied during the cladding of FGMs can cause microstructural influencing the clad mechanical properties. As an example, Ostolaza et al [155] investigated the clad quality characteristics of functionally graded AISI 316L and AISI H13 produced by the DED method on AISI 1045 mild steel substrate as the material composition was changed. The first layer was initially deposited with 100% AISI 316L, then the composition was changed at intervals of 20 wt% until the top layer with 100% AISI H13, as shown in Figure 35.…”

“…Carroll et al [156] also concluded that variation in composition can alter the FGM microhardness properties along the length of the gradient zone, as depicted in Figure 36. They employed the DED method to deposit 20 layers of SS304L followed by nineteen layers Furthermore, variation in composition also affects the wear and corrosion resistance of FGMs, as seen in the work of Ostolaza et al [155]. The corrosion resistance was reduced when the composition was varied from SS316L to AISI H13 because 316L contains higher chromium content of 16% and makes it have higher corrosion resistance, but it is reduced due to the increase in H13 content which has a lower chromium content of about 5%, leading to poor corrosion resistance at the top layer [157].…”