Purpose

This study aims to reveal that fatigue life is improved using heat treatment in the rotational bending fatigue test, which determines the fatigue behavior closest to service conditions.

Design/methodology/approach

It is essential to know the mechanical behavior of the parts produced by additive manufacturing under service conditions. In general, axial stress and plane bending tests are used by many researchers because they are practical: the service conditions cannot be sufficiently stimulated. For this reason, the rotating bending fatigue test, which represents the conditions closest to the service conditions of a load-bearing machine element, was chosen for the study. In this study, the rotational bending fatigue behavior of X3NiCoMoTi18-9–5 (MS1) maraging steel specimens produced by the selective laser melting (SLM) technique was experimentally investigated under various heat treatments conditions.

Findings

As a result of the study, MS1 produced by additive manufacturing is a material suitable for heat treatment that has enabled the heat treatment to affect fatigue strength positively. Cracks generally initiate from the outer surface of the sample. Fabrication defects have been determined to cause all cracks on the sample surface or regions close to the surface.

Research limitations/implications

While producing the test sample, printing was vertical to the print bed, and various heat treatments were applied. The rotating bending fatigue test was performed on four sample groups comprising as-fabricated, age-treated, solution-treated and solution + age-treated conditions.

Originality/value

Most literature studies have focused on the axial fatigue strength, printing orientation and heat treatment of maraging steels produced with Direct Metal Laser Sintering (DMLS); many studies have also investigated crack propagation behaviors. There are few studies in the literature covering conditions of rotating bending fatigue. However, the rotating bending loading state is the service condition closest to modern machine element operating conditions. To fill this gap in the literature, the rotating bending fatigue behavior of the alloy, which was maraging steel (X3NiCoMoTi18-9–5, 1.2709) produced by SLM, was investigated under a variety of heat treatment conditions in this study.

中文翻译：

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热处理对3D打印马氏体时效钢疲劳行为的影响

目的

本研究旨在揭示在旋转弯曲疲劳试验中使用热处理可提高疲劳寿命，这决定了最接近使用条件的疲劳行为。

设计/方法/方法

了解增材制造生产的零件在使用条件下的机械性能至关重要。一般来说，许多研究人员使用轴向应力和平面弯曲试验，因为它们很实用：不能充分刺激使用条件。出于这个原因，研究选择了旋转弯曲疲劳试验，它代表了最接近承载机器元件的使用条件的条件。在这项研究中，通过选择性激光熔化 (SLM) 技术生产的 X3NiCoMoTi18-9-5 (MS1) 马氏体时效钢试样在各种热处理条件下的旋转弯曲疲劳行为进行了实验研究。

发现

研究结果表明，通过增材制造生产的 MS1 是一种适用于热处理的材料，使热处理能够对疲劳强度产生积极的影响。裂纹通常从样品的外表面开始。制造缺陷已被确定为导致样品表面或靠近表面区域的所有裂纹。

研究限制/影响

在生产测试样品时，打印垂直于打印床，并进行了各种热处理。旋转弯曲疲劳试验是在四个样品组上进行的，包括制造的、时效处理的、固溶处理的和固溶+时效处理的条件。

原创性/价值

大多数文献研究都集中在直接金属激光烧结 (DMLS) 生产的马氏体时效钢的轴向疲劳强度、印刷取向和热处理上；许多研究还研究了裂纹扩展行为。关于旋转弯曲疲劳条件的文献研究很少。然而，旋转弯曲载荷状态是最接近现代机械元件运行条件的使用条件。为了填补文献中的这一空白，本研究研究了 SLM 生产的马氏体时效钢 (X3NiCoMoTi18-9-5, 1.2709) 在各种热处理条件下的旋转弯曲疲劳行为。