Mechanical properties of laser powder bed fusion processed Inconel alloy IN718 in different heat treatment conditions through small scale specimen testing

IF 5 2区工程技术 Q1 ENGINEERING, MECHANICAL

Theoretical and Applied Fracture Mechanics Pub Date : 2024-11-13 DOI:10.1016/j.tafmec.2024.104756

Kartikey Sharma , Ravi Ranjan Kumar , S. Dinesh Raj , Sushant K. Manwatkar , Kuruvilla Joseph , S.V.S. Narayana Murty

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Abstract

In this study, IN-718 samples were printed using laser powder bed fusion (LPBF) process to investigate the effect of printing parameters (in terms of Volume Energy Density, (VED)), printing orientation, heat treatment and test temperature on the microstructure and mechanical properties. Tensile properties were evaluated using small-scale tensile specimens extracted from samples printed with 15 different processing parameters (by varying scan speed and scan power) in two print orientations (XY and XZ plane), in three microstructural conditions (as-printed (AP), printed + solution treated and aged (STA), printed + hot isostatically pressed (HIP) + STA), at two different temperatures (room temperature and 650 °C). The mechanical properties obtained from testing of small-scale tensile specimens were compared with results obtained from testing of specimens following ASTM E8 standard, to understand effect of specimen size on mechanical properties. Based on microstructural analysis, it was observed that below a VED value of 50 J/mm³, the conduction region prevailed, with the presence of irregular lack of fusion porosities. In VED range of 50–100 J/mm³, the transition prevailed with highly dense samples (over 99 % of theoretical density) with minimal porosity. Above a VED of 100 J/mm³, the keyhole regime prevailed with the presence of spherical keyhole porosities. STA heat treatment improved YS and UTS to ∼1200 and ∼1400 MPa, respectively, while reducing ductility to ∼15 %. HIP + STA had similar effect on tensile properties as STA heat treatment. Based on tensile strength data, it was observed that HIP is not essential for parts printed with optimum parameters. Sample size in the present study was found to have an insignificant effect on tensile properties. In conclusion, the study provides an insight into the role played by printing parameters, printing orientation, and post-processing on defects, microstructures and thereby on the mechanical properties.

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通过小规模试样测试了解不同热处理条件下激光粉末床熔融加工因科镍合金 IN718 的机械性能

本研究采用激光粉末床熔融（LPBF）工艺打印了 IN-718 样品，以研究打印参数（体积能量密度（VED））、打印方向、热处理和测试温度对微观结构和机械性能的影响。在两种不同的温度（室温和 650 °C）下，使用 15 种不同的加工参数（通过改变扫描速度和扫描功率）从两种印刷方向（XY 平面和 XZ 平面）、三种微观结构条件（原样印刷 (AP)、印刷 + 溶液处理和老化 (STA)、印刷 + 热等静压 (HIP) + STA）下印刷的样品中提取的小尺寸拉伸试样进行了拉伸性能评估。小尺寸拉伸试样测试获得的机械性能与按照 ASTM E8 标准测试试样获得的结果进行了比较，以了解试样尺寸对机械性能的影响。根据微观结构分析，可以发现在 VED 值为 50 J/mm3 以下时，传导区域占主导地位，存在不规则的熔融孔隙。在 50-100 焦耳/立方毫米的 VED 值范围内，高密度样品（超过理论密度的 99%）和最小孔隙率的过渡占主导地位。当 VED 超过 100 J/mm3 时，则出现了球形键孔气孔。STA 热处理将 YS 和 UTS 分别提高到 ∼1200 MPa 和 ∼1400 MPa，同时将延展性降低到 ∼15%。HIP + STA 对拉伸性能的影响与 STA 热处理相似。根据拉伸强度数据，可以看出 HIP 对采用最佳参数印刷的零件来说并不重要。本研究发现，样品大小对拉伸性能的影响不大。总之，本研究深入探讨了印刷参数、印刷方向和后处理对缺陷、微结构以及机械性能的影响。

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来源期刊

Theoretical and Applied Fracture Mechanics 工程技术-工程：机械

CiteScore

8.40

自引率

18.90%

发文量

435

审稿时长

37 days

期刊介绍： Theoretical and Applied Fracture Mechanics'' aims & scopes have been re-designed to cover both the theoretical, applied, and numerical aspects associated with those cracking related phenomena taking place, at a micro-, meso-, and macroscopic level, in materials/components/structures of any kind. The journal aims to cover the cracking/mechanical behaviour of materials/components/structures in those situations involving both time-independent and time-dependent system of external forces/moments (such as, for instance, quasi-static, impulsive, impact, blasting, creep, contact, and fatigue loading). Since, under the above circumstances, the mechanical behaviour of cracked materials/components/structures is also affected by the environmental conditions, the journal would consider also those theoretical/experimental research works investigating the effect of external variables such as, for instance, the effect of corrosive environments as well as of high/low-temperature.