Pure iron is a promising candidate for biodegradable temporary orthopedic implants due to its biocompatibility, favorable mechanical strength, and non-toxic degradation products. Atomet 195 SP is a high-purity water-atomized iron powder commercially produced for food enrichment, pharmaceutical-related, and other non-structural applications. Its commodity-scale water-atomization production route may offer a cost advantage over specialty gas-atomized additive manufacturing feedstocks; however, this powder has not previously been evaluated for laser powder bed fusion (L-PBF). This study presents the first investigation of its processability by L-PBF, systematically establishing process–structure–property relationships across a volumetric energy density (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(E_v\)</EquationSource> </InlineEquation>) range of 34.09–120.00J mm−3. A Taguchi L16 orthogonal array was used to evaluate scanning speed, hatch spacing, and laser spot size. Scanning speed was identified as the dominant control factor for porosity (63.49% contribution, <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(p = 0.007\)</EquationSource> </InlineEquation>) and surface roughness (57.76% contribution, <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(p = 0.003\)</EquationSource> </InlineEquation>), with hatch spacing playing a significant secondary role; spot size was statistically insignificant. A processing window of 66–100J mm−3 yielded near-full densification, with a minimum porosity of 0.06% at <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(E_{v} = 85.71J\;{\text{mm}}^{{ - 3}}\)</EquationSource> </InlineEquation> —notably higher than the 47–55J mm−3 optimum reported for Atomet FeAM on the same machine, confirming that parameter transfer between water-atomized powder grades is not reliable. Within this optimal window, the material achieved porosities below 0.5%, Vickers hardness values of 148 to − 159HV, ultimate tensile strengths of 449.4-508.1MPa, yield strengths of 413.3-466.2MPa, and elongations of 14.1–22.8%. EBSD analysis revealed a fine ferritic microstructure with grain sizes of 4.0–5.3 μm and no detectable secondary phases. A pronounced yield point phenomenon at high energy densities progressively attenuated with decreasing energy input. Two specimens fabricated with different parameter combinations at the same nominal <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\(E_v\)</EquationSource> </InlineEquation> exhibited subtle differences in grain size and mechanical response, reinforcing the limitation of energy density as a sole process descriptor. These results demonstrate that this low-cost water-atomized powder can be successfully processed by L-PBF with mechanical properties comparable to gas-atomized iron feedstocks, supporting its potential for biodegradable implant development.

From food enrichment to additive manufacturing: process–structure–property relationships of Atomet 195 SP water-atomized pure iron powder fabricated via laser powder bed fusion

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2026年7月3日

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Pedro Lopes,
Catarina Costa,
João Castro,
João Matos,
Luís Garrido,
Jorge Alves

摘要

Pure iron is a promising candidate for biodegradable temporary orthopedic implants due to its biocompatibility, favorable mechanical strength, and non-toxic degradation products. Atomet 195 SP is a high-purity water-atomized iron powder commercially produced for food enrichment, pharmaceutical-related, and other non-structural applications. Its commodity-scale water-atomization production route may offer a cost advantage over specialty gas-atomized additive manufacturing feedstocks; however, this powder has not previously been evaluated for laser powder bed fusion (L-PBF). This study presents the first investigation of its processability by L-PBF, systematically establishing process–structure–property relationships across a volumetric energy density ( \(E_v\) ) range of 34.09–120.00J mm⁻³. A Taguchi L16 orthogonal array was used to evaluate scanning speed, hatch spacing, and laser spot size. Scanning speed was identified as the dominant control factor for porosity (63.49% contribution, \(p = 0.007\) ) and surface roughness (57.76% contribution, \(p = 0.003\) ), with hatch spacing playing a significant secondary role; spot size was statistically insignificant. A processing window of 66–100J mm⁻³ yielded near-full densification, with a minimum porosity of 0.06% at \(E_{v} = 85.71J\;{\text{mm}}^{{ - 3}}\) —notably higher than the 47–55J mm⁻³ optimum reported for Atomet FeAM on the same machine, confirming that parameter transfer between water-atomized powder grades is not reliable. Within this optimal window, the material achieved porosities below 0.5%, Vickers hardness values of 148 to − 159HV, ultimate tensile strengths of 449.4-508.1MPa, yield strengths of 413.3-466.2MPa, and elongations of 14.1–22.8%. EBSD analysis revealed a fine ferritic microstructure with grain sizes of 4.0–5.3 μm and no detectable secondary phases. A pronounced yield point phenomenon at high energy densities progressively attenuated with decreasing energy input. Two specimens fabricated with different parameter combinations at the same nominal \(E_v\) exhibited subtle differences in grain size and mechanical response, reinforcing the limitation of energy density as a sole process descriptor. These results demonstrate that this low-cost water-atomized powder can be successfully processed by L-PBF with mechanical properties comparable to gas-atomized iron feedstocks, supporting its potential for biodegradable implant development.