Mechanical behaviour and interface evaluation of hybrid MIM/PBF stainless steel components

Abstract

Purpose The paper reports an investigation into the mechanical behaviour of hybrid components produced by combining the capabilities of metal injection moulding (MIM) with the laser-based powder bed fusion (PBF) process to produce small series of hybrid components. The research investigates systematically the mechanical properties and the performance of the MIM/PBF interfaces in such hybrid components. Design/methodology/approach The MIM process is employed to fabricate relatively lower cost preforms in higher quantities, whereas the PBF technology is deployed to build on them sections that can be personalised, customised or functionalised to meet specific technical requirements. Findings The results are discussed, and conclusions are made about the mechanical performance of such hybrid components produced in batches and also about the production efficiency of the investigated hybrid manufacturing (HM) route. The obtained results show that the proposed HM route can produce hybrid MIM/PBF components with consistent mechanical properties and interface performance which comply with the American Society for Testing and Materials (ASTM) standards. Originality/value The manufacturing of hybrid components, especially by combining the capabilities of additive manufacturing processes with cost-effective complementary technologies, is designed to be exploited by industry because they can offer flexibility and cost advantages in producing small series of customisable products. The findings of this research will contribute to further develop the state of the art in regards to the manufacturing and optimisation of hybrid components.

The Effect of Hot Isostatic Pressing on Surface Integrity, Microstructure and Strength of Hybrid Metal Injection Moulding, and Laser-Based Powder Bed Fusion Stainless-Steel Components

“…The fracture of the hybrid tensile specimens occurred as a result of the reduced cross section of the tensile samples at the PBF sections, for all sets of samples. This is attributed to the vertical build orientation of the PBF section and to the high UTS of the preforms, and conforms to the reported results [19,55]. In particular, the microstructure of the MIM was optimised after the HIP treatment, as a result of the pore shrinkage and consequently led to an enhanced performance.…”

“…The L-PBF sections on top of the MIM preforms, were built using the EOS 316 L stainless steel powder, in particle sizes of 20-65 µm, with the following process parameters: Laser power 180 W; scanning speed 1300 mm/s; energy density 83 J/mm 3 in a protective gas environment to prevent oxidation. The parameters used to build the L-PBF sections and also the details associated with the pre-processing of the preforms and subsequently with the post-processing of hybrid parts are provided in the research reported earlier [19]. Fifteen hybrid tensile bars were produced in this way and then they were split into three sets.…”

“…Currently, the research on the HCM route is mostly focused on developing the necessary tooling and software solutions [17,18]. Some pilot HCM implementations for producing a small series of hybrid components have been reported where standardised minimum requirements have been met [19]. However, some further post-processing, i.e., heat treatment (HT), was required as some embrittlement at the MIM/laser-based powder bed fusion (L-PBF) joints was observed [19].…”

“…Some pilot HCM implementations for producing a small series of hybrid components have been reported where standardised minimum requirements have been met [19]. However, some further post-processing, i.e., heat treatment (HT), was required as some embrittlement at the MIM/laser-based powder bed fusion (L-PBF) joints was observed [19]. This was attributed to some residual stress concentration but a methodology and/or study to overcome the stated shortcomings were not provided.…”

Powder-based laser hybrid additive manufacturing of metals: a review

“…13 Surface finish of samples in (a) as deposited and after machining states [62] Fig. 14 Image of the cladding head, touch probe, and end mill co-existing in the tool changer [135] producing small series of hybrid 316L stainless steel components [138]. The mechanical properties and interfaces of such hybrid MIM/LPBF components were investigated and it was reported that they were similar and even better than those of monolithic MIM parts while conforming fully to the ASTM standards for 316L stainless steel parts.…”