Effect of Laser Spot Size, Scanning Strategy, Scanning Speed, and Laser Power on Microstructure and Mechanical Behavior of 316L Stainless Steel Fabricated via Selective Laser Melting

Although the concept of additive manufacturing has been proposed for several decades, momentum of selective laser melting (SLM) is finally starting to build. In SLM, density and surface roughness, as the important quality indexes of SLMed parts, are dependent on the processing parameters. However, there are few studies on their collaborative optimization in SLM to obtain high relative density and low surface roughness simultaneously in the previous literature. In this work, the response surface method was adopted to study the influences of different processing parameters (laser power, scanning speed and hatch space) on density and surface roughness of 316L stainless steel parts fabricated by SLM. The statistical relationship model between processing parameters and manufacturing quality is established. A multi-objective collaborative optimization strategy considering both density and surface roughness is proposed. The experimental results show that the main effects of processing parameters on the density and surface roughness are similar. It is noted that the effects of the laser power and scanning speed on the above objective quality show highly significant, while hatch space behaves an insignificant impact. Based on the above optimization, 316L stainless steel parts with excellent surface roughness and relative density can be obtained by SLM with optimized processing parameters.

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Cavitation erosion resistance of 316L stainless steel fabricated using selective laser melting

Friction ◽

10.1007/s40544-020-0443-7 ◽

2020 ◽

Author(s):

Hongqin Ding ◽

Qing Tang ◽

Yi Zhu ◽

Chao Zhang ◽

Huayong Yang

Keyword(s):

Stainless Steel ◽

Selective Laser Melting ◽

Laser Power ◽

Cavitation Erosion ◽

316L Stainless Steel ◽

Erosion Resistance ◽

Scanning Speed ◽

Laser Melting ◽

Cavitation Damage ◽

Cavitation Erosion Resistance

AbstractCavitation erosion degrades the performance and reliability of hydraulic machinery. Selective laser melting (SLM) is a type of metal additive manufacturing technology that can fabricate metal parts directly and provide lightweight design in various industrial applications. However, the cavitation erosion behaviors of SLM-fabricated parts have rarely been studied. In this study, SLM 316L stainless steel samples were fabricated via SLM technology considering the scanning strategy, scanning speed, laser power, and build orientation. The effect of the process parameters on the cavitation erosion resistance of the SLM-fabricated 316L stainless steel samples was illustrated using an ultrasonic vibratory cavitation system. The mass loss and surface topography were employed to evaluate the surface cavitation damage of the SLM-fabricated 316L stainless steel samples after the cavitation test. The cavitation damage mechanism of the SLM-fabricated samples was discussed. The results show that the degree of cavitation damage of the sample fabricated via SLM with a few defects, anisotropic build direction, and columnar microstructure is significantly decreased. Defects such as pores, which are attributed to low laser power and high scanning speed, may severely aggravate the cavitation damage of the SLM-fabricated samples. The sample fabricated via SLM with a low laser power and exposure time exhibited the highest porosity and poor cavitation erosion resistance. The cellular structures are more prone to cavitation damage compared with the columnar structures. A sample with a high density of grain boundaries will severely suffer cavitation damage.

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An Investigation on Residual Stress in 316L Stainless Steel by Selective Laser Melting

Volume 1: Additive Manufacturing; Bio and Sustainable Manufacturing ◽

10.1115/msec2018-6701 ◽

2018 ◽

Author(s):

Peiying Bian ◽

Jing Shi ◽

Xiaodong Shao ◽

Jingli Du ◽

Jun Dai ◽

...

Keyword(s):

Residual Stress ◽

Stainless Steel ◽

Selective Laser Melting ◽

Laser Power ◽

316L Stainless Steel ◽

Melting Process ◽

Scanning Speed ◽

Tensile Residual Stress ◽

Laser Melting ◽

Process Factors

In this paper, the residual stress of 316L stainless steel obtained from selective laser melting process is measured, and the process factors that influence residual stress are analyzed. Two levels of laser power, two levels of scanning speed, and other auxiliary factors such as height of support structure are considered. For each combination of condition, the residual stress is measured at three in-depth positions, and the microstructure is also observed. The results show that the as-built 316L samples have fine microstructure with no clear grain boundaries, and the residual stresses at all measuring depths are tensile for all as-built SLM specimens. Meanwhile, it is found that the higher laser power and the lower scanning speed lead to the increase of tensile residual stress. Also, the tensile residual stress tends to increase with the depth into surface. In addition, the increase in position symmetry of specimen on the build platform appears to be able to reduce the magnitude of tensile residual stress. On the other hand, the effects of specimen location with respect to powder spreading and height of support are less conclusive.

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Effects of laser power on the microstructure and mechanical properties of 316L stainless steel prepared by selective laser melting

International Journal of Modern Physics B ◽

10.1142/s0217979217440155 ◽

2017 ◽

Vol 31 (16-19) ◽

pp. 1744015 ◽

Cited By ~ 3

Author(s):

Zeng Zheng ◽

Lianfeng Wang ◽

Biao Yan

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Stainless Steel ◽

Selective Laser Melting ◽

Laser Power ◽

Laser Scanning ◽

316L Stainless Steel ◽

Laser Melting ◽

Scanning Strategy ◽

Microstructure And Mechanical Properties

Selective laser melting (SLM) was used to prepare 316L stainless steel parts and the effects of laser power on the microstructure and mechanical properties of the final products were studied. With increasing applied laser power, the defects of as-built parts were reduced greatly and the as-built parts presented a highest relative density of 99.1%. The tensile strength of samples was significantly improved from 321 ± 10 MPa to 722 ± 10 MPa. The microhardness was homogeneous; the residual stresses in the samples were tensile, which were higher in the section perpendicular to the laser scanning strategy. The probable reasons for this phenomenon were proposed.

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Collaborative Optimization of Density and Surface Roughness of 316L Stainless Steel in Selective Laser Melting

Materials ◽

10.3390/ma13071601 ◽

2020 ◽

Vol 13 (7) ◽

pp. 1601 ◽

Cited By ~ 2

Author(s):

Yong Deng ◽

Zhongfa Mao ◽

Nan Yang ◽

Xiaodong Niu ◽

Xiangdong Lu

Keyword(s):

Surface Roughness ◽

Stainless Steel ◽

Relative Density ◽

Selective Laser Melting ◽

Laser Power ◽

316L Stainless Steel ◽

Scanning Speed ◽

Processing Parameters ◽

Collaborative Optimization ◽

Laser Melting

Although the concept of additive manufacturing has been proposed for several decades, momentum in the area of selective laser melting (SLM) is finally starting to build. In SLM, density and surface roughness, as the important quality indexes of SLMed parts, are dependent on the processing parameters. However, there are few studies on their collaborative optimization during SLM to obtain high relative density and low surface roughness simultaneously in the literature. In this work, the response surface method was adopted to study the influences of different processing parameters (laser power, scanning speed and hatch space) on density and surface roughness of 316L stainless steel parts fabricated by SLM. A statistical relationship model between processing parameters and manufacturing quality is established. A multi-objective collaborative optimization strategy considering both density and surface roughness is proposed. The experimental results show that the main effects of processing parameters on the density and surface roughness are similar. We observed that the laser power and scanning speed significantly affected the above objective quality, but the influence of the hatch spacing was comparatively low. Based on the above optimization, 316L stainless steel parts with excellent surface roughness and relative density can be obtained by SLM with optimized processing parameters.

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