Effect of deposition efficiency on microstructure and property of 316L stainless steel fabricated by laser engineered net shaping

Pei Miao; Fangyong Niu; Guangyi Ma; Jianzhong Lü; Dongjiang Wu

doi:10.3969/j.issn.1003-501X.2017.04.005

Article navigation > Opto-Electronic Engineering > 2017 Vol. 44 > No. 4 > 410-417

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Pei Miao, Fangyong Niu, Guangyi Ma, et al. Effect of deposition efficiency on microstructure and property of 316L stainless steel fabricated by laser engineered net shaping[J]. Opto-Electronic Engineering, 2017, 44(4): 410-417. doi: 10.3969/j.issn.1003-501X.2017.04.005

Citation:

Pei Miao, Fangyong Niu, Guangyi Ma, et al. Effect of deposition efficiency on microstructure and property of 316L stainless steel fabricated by laser engineered net shaping[J]. Opto-Electronic Engineering, 2017, 44(4): 410-417. doi: 10.3969/j.issn.1003-501X.2017.04.005

Effect of deposition efficiency on microstructure and property of 316L stainless steel fabricated by laser engineered net shaping

1.
Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China
2.
Dalian Sunlight Machinery Co., Ltd., Dalian 116024, China

Fund Project:

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Corresponding author: Dongjiang Wu, E-mail: djwudut@dlut.edu.cn

Received Date 13 November 2016

Revised Date 04 January 2017

Published Date 15 April 2017

Abstract

Abstract

Laser engineered net shaping is a promising technique to fabricate high-performance components with complex geometry rapidly. Excellent properties of fabricated specimen and high deposition efficiency are both important for this additive manufacturing method, but few researches have been done on the relationship between them. In this paper, single-bead multilayer structures of 316L stainless steel are fabricated by laser engineered net shaping (LENS). Using the same laser power and scanning speed, different deposition efficiencies are achieved by adjusting powder flow rate and layer increment. Microstructures and mechanical properties of the deposited structures under different deposition efficiencies are discussed. The results show that, for certain laser power and scanning speed, the deposition efficiency increases from 12.41 mm³/s to 22.62 mm³/s with the increase of the powder flow rate and layer increment, which increases by 86.3% compared with the initial process. Laser energy consumed by depositing unit effective volume reduces from initial 98.84 J/mm³ to 53.06 J/mm³ and the energy efficiency increases by 46.32%. Microstructures of the specimen consist of columnar dendrite and the dendrite length increases obviously with the deposition efficiency. Property test shows that properties of the specimen under different deposition efficiencies are consistent and do not decrease with the deposition efficiency. Tensile strength and yield strength are stable in 510 MPa and 290 MPa, respectively. The elongation rate is around 40% while the micro-hardness is about 180 HV, all of which have reached the same level of forging. The results illustrate that the deposition efficiency and mechanical property can be optimized, which achieves fabrication of high performance parts with low energy consumption and high efficiency.
- laser engineered net shaping /
- 316L stainless steel /
- deposition efficiency /
- microstructure /
- mechanical property

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References

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Overview

Overview

Abstract:Laser engineered net shaping is a promising additive manufacturing technique that can be used for building three-dimensional components directly from CAD models by layer-wise deposition. Components with high performance and complex geometry can be achieved rapidly by this technology, and components of metal, ceramic or composite material have been successfully fabricated and used in many industrial field. High properties of fabricated specimens and high deposition efficiency are both important for laser engineered net shaping, but few researches have been done on the relationship between them. In this paper, single-bead multilayer structures of 316L stainless steel are fabricated by laser engineered net shaping system. Using the same laser power and scanning speed, different deposition efficiencies are achieved by adjusting powder flow rate and layer increment. Microstructure of each specimen is analyzed by SEM. Tensile strength and micro-hardness of the deposited structures under different deposition efficiencies are tested, respectively. Effect of deposition efficiency on microstructure and properties of fabricated 316L stainless steel are discussed. The results show that, for certain laser power and scanning speed, the deposition efficiency increases from 12.41 mm³/s to 22.62 mm³/s with the increase of the powder flow rate and layer increment, which increases by 86.3% compared with the initial process. Laser energy consumed by depositing unit effective volume reduces from initial 98.84 J/mm³ to 53.06 J/mm³ and the energy efficiency increases by 46.32%. Microstructure of the specimen consists of columnar dendrite and the dendrite length increases obviously with the deposition efficiency. Property test results show that properties of the specimens under different deposition efficiencies are consistent and do not decrease with the deposition efficiency. Tensile strength and yield strength are stable in 510 MPa and 290 MPa, respectively, and the elongation rate is around 40%. The precipitation of inclusions between grain boundaries is the main reason for the generation of tensile initial defects. Micro-hardness near the substrate of all specimens is higher than other position due to finer microstructure resulted from faster conduction heat dissipation through substrate. As a whole, the micro-hardness is stable at 173~184 MPa. Both the tensile property and micro-hardness of fabricated specimens have reached the same levels of forging. The research in this paper illustrates that the deposition efficiency of laser engineered net shaping and mechanical properties of fabricated structures can be optimized together during certain process window, which achieves fabrication of high performance parts with low energy consumption and high efficiency.