Effect of Annealing Heat Treatment on the Microstructural Evolution and Mechanical Properties of Hot Isostatic Pressed 316L Stainless Steel Fabricated by Laser Powder Bed Fusion

Chadha, Kanwal; Tian, Yuan; Spray, John G.; Aranas, Clodualdo

doi:10.3390/met10060753

Cited by 48 publications

(25 citation statements)

References 47 publications

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“…The powder residues inside the pores suggested that this is a LOF porosity, despite their round shape and use of a higher laser power. The comparison of the mechanical properties of samples prepared by SLM under the stated conditions revealed that both yield strength and tensile strength reached higher values than Lavery, Rottger or Chadha [ 2 , 4 , 12 ] and also higher ductility. However, the ductility did not reach as high values (76%) as Puichaud states for samples of 316 L steel prepared by SLM [ 17 ].…”

Section: Resultsmentioning

confidence: 99%

“…As previously mentioned, in the case of 316 L steel after SLM, there is always a certain proportion of porosity, and the content of which significantly depends on the used conditions [ 2 , 5 , 6 , 9 , 12 ]. Figure 13 shows the different levels of porosity in the structure of the samples prepared under different SLM conditions.…”

Section: Resultsmentioning

confidence: 99%

“…However, the ductility did not reach as high values (76%) as Puichaud states for samples of 316 L steel prepared by SLM [ 17 ]. However, it must be taken into account that the samples prepared in the context of our study were built in the vertical direction, which, as some publications state [ 2 , 4 , 12 ], is not as suitable in terms of mechanical properties as the horizontal direction. Therefore, it can be assumed that with use of the horizontal direction of preparation, the values of mechanical properties would be even higher.…”

Section: Resultsmentioning

confidence: 99%

“…Montero-Sistiaga [ 5 ] states that when using a laser with a power of 400 and 1000 W for preparation of samples from 316 L steel, HIP was effective to eliminate porosity and cracks, while the conditions of HIP were similar to those of Rottger, namely 1155 °C/100 MPa/3 h. Additively manufactured 316 L stainless steel usually requires post-processing heat treatment (recovery, homogenization, annealing) to maximize strength and ductility. The application of heat treatments removes the melt pool boundaries and microsegregation in the as-printed material [ 12 , 13 , 14 ]. Those microstructural differences influence mechanical properties such as resilience behavior [ 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

“…The aim of this article is to primarily test the different laser power, exposure times and scanning strategy (meander, chessboard) during the preparation on the microstructure and distribution of porosity in the samples, and to describe the effect of HIP on the elimination of porosity, microstructural changes and mechanical properties of 316 L steel. In addition, another aim of the article is to determine the effect of the higher applied pressure (190 MPa) during HIP, because for almost all available publications concerning HIP of SLM parts of 316 L steels, a maximum pressure of 150 MPa was used [ 2 , 4 , 5 , 12 ]. A prediction is that higher pressure can be significantly more effective for elimination of porosity during HIP.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Hot Isostatic Pressing on Porosity and Mechanical Properties of 316 L Stainless Steel Prepared by the Selective Laser Melting Method

et al. 2020

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The manufacturing route primarily determines the properties of materials prepared by additive manufacturing methods. In this work, the microstructural features and mechanical properties of 316 L stainless steel prepared by the selective laser method have been determined. Three types of samples, (i) selective laser melted (SLM), (ii) selective laser melted and hot isostatic pressed (HIP) and (iii) selective laser melted and heat treated (HT), were characterized. Microstructural analysis revealed that SLM samples were formed by melt pool boundaries with fine cellular–dendritic-type microstructure. This type of microstructure disappeared after HT or HIP and material were formed by larger grains and sharply defined grain boundaries. The SLM-prepared samples contained different levels of porosity depending on the preparation conditions. The open interconnected LOF (lack of fusion) pores were observed in the samples, which were prepared with using of scanning speed 1200 mm/s. The blowhole and keyhole type of porosity were observed in the samples prepared by lower scanning speeds. The HIP caused a significant decrease in internal closed porosity to 0.1%, and a higher pressure of 190 MPa was more effective than the usually used pressure of 140 MPa, but for samples with open porosity, HIP was not effective. The relatively high yield strength of 570 MPa, tensile strength of 650 MPa and low ductility of 30–34% were determined for SLM samples with the lower porosity content than 1.3%. The samples after HIP showed lower yield strengths than after SLM (from 290 to 325 MPa) and relatively high ductility of 47.8–48.5%, regardless of the used SLM conditions.

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