Parametric investigation and characterization of 17-4 PH stainless steel parts fabricated by selective laser melting

Abstract

The present study performed parametric investigation and characterizations on 17-4 PH stainless steel built by selective laser melting. Cubical samples were deposited by considering process parameters (laser power and scan speed) and scan strategy (design parameter) to investigate relative density and microhardness. Relative density and micro hardness were the maximum for samples with medium energy density and when hexagonal inside-out scan strategy was used. They were the minimum for the sample with low energy density and when strip alternate scan strategy was used. Austenite, ferrite, and small molten pools were observed on the side surface of samples from optical and scanning electron microstructure analysis. From energy dispersive spectroscopy analysis, a variation of chemical composition was observed among the samples, resulting in variation in relative density and microhardness. Austenite phase and ferrite peak at the highest intensity were also observed by X-ray diffraction for medium energy density sample. Electron backscattered diffraction results showed an increase in austenite phase with increased energy density, resulting in a microhardness change. Residual stresses induced were more for low energy density samples compared to medium energy density samples. A higher corrosion resistance (<0.5 mm/a) and an absence of corrosion cracks were present for all samples with different energy densities.

摘要

本文对选择性激光熔化的17-4 PH不锈钢进行了参数化研究和表征。通过改变工艺参数包括激 光功率和扫描速度以及扫描方式(设计参数)来研究试样的相对密度和显微硬度的变化。当使用中等能 量密度和内外六角扫描方式时, 试样的相对密和显微硬度最大;当使用低能量密度和交替带状扫描方 式时, 试样的相对密和显微硬度最小。在光学和扫描电子显微组织中, 试样侧面有奥氏体、铁素体和 小熔池。能量色散光谱分析表明, 试样的化学成分变化导致相对密度和显微硬度发生变化。X射线衍 射结果表明, 中等能量密度试样的奥氏体相和铁素体峰强度最高。背散射电子衍射结果表明, 随着能 量密度的增加, 奥氏体相增加, 导致试样的显微硬度变化。相比于中等能密度试样, 低能量密度试样 易诱发更多的残余应力。采用不同能量密度得到的样品都具有较强的耐蚀性(0.05 mm/a), 未出现明显 的腐蚀裂纹。