Transformation of austenite to duplex austenite-ferrite assembly in annealed stainless steel 316L consolidated by laser melting

Saeidi, Kamran; Gao, Xiang; Lofaj, František; Kvetková, Lenka; Shen, Zhijian

doi:10.1016/j.jallcom.2015.01.249

Cited by 227 publications

(121 citation statements)

References 16 publications

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“…As expected from the visual inspection of the EBSD maps, the 1050°C heat-treated samples have an average grain size over twice the size of the as-built samples. This corresponds well with previous findings 19,20 where annealed SLM 316L samples had much larger grain sizes than in their as-built condition. According to these papers, one can predict a proportional relation between grain size and annealing time.…”

Section: Microstructural Analysissupporting

confidence: 93%

“…Selective laser melting 316L has been reported to inhibit large tensile residual stresses in its as‐built condition, while most of these residual stresses have been successfully removed by 650°C stress relieving . However, stress relieving at 650°C causes no changes in microstructure as the elevated temperature is below the recrystallization temperature of 316L . This implies that the stress‐relieved samples in this study have the same microstructure characteristics as the as‐built samples.…”

Section: Discussionmentioning

confidence: 81%

“…No grain growth has been reported for SLM 316L at 650°C in previous studies, while grain growth has been observed from 800°C upward . 316L stays austenitic for all temperatures, even though a small increase in ferrite fraction has been reported for SLM 316L heat treated at 1100°C . To investigate the effect of residual stresses on the fatigue crack growth behaviour of 316L steel, stress relieving heat treatment was conducted on 6 of the samples, 3 with 0° and 3 with 45° building orientation.…”

Section: Methodsmentioning

confidence: 93%

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Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

Fergani

Wold²,

Berto³

et al. 2017

Fatigue Fract Eng Mat Struct

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This study is focused on stainless steel type 316L produced by selective laser melting (SLM). This steel is very resistant to corrosion in acidic environments and has extremely good strength properties at elevated temperatures. It is also characterized by a very good weldability. These properties allow for various applications of 316L in different fields. The widespread application of 316L opens up various possibilities for production of parts using SLM. Therefore, it is important to characterize the fatigue crack growth behaviour. In the present paper, the crack growth behaviour of SLM 316L stainless steel has been investigated in its as‐built condition and in different heat treatment conditions. The effect of build orientation on the crack growth path is also studied by performing fatigue crack growth tests on compact tension specimens built at 0° and 45° orientations relative to the build direction. A heat treatment above the recrystallization temperature followed by quenching is shown to create compressive residual stresses that improve the resistance against crack propagation considerably. The 45° build orientation shows crack propagation at an angle to the initial notch plane, which reveals that anisotropy still persists after heat treatment.

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Section: Microstructural Analysissupporting

confidence: 93%

Section: Discussionmentioning

confidence: 81%

Section: Methodsmentioning

confidence: 93%

See 1 more Smart Citation

Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

Fergani

Wold²,

Berto³

et al. 2017

Fatigue Fract Eng Mat Struct

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show abstract

“…Figure 6 shows changes in dislocation density and structures in the steel before and after annealing. The changes are similar to other reported observations [12,22]. A side-effect of the heat treatment carried out in the oxidative air environment was surface oxidation of the specimens.…”

Section: Figure 4: Evolution Of Primary Cell Size In Relation To the supporting

confidence: 91%

Microstructural and Thermal Stability of Selective Laser Melted 316l Stainless Steel Single Tracks

Krakhmalev

Yadroitsava

Fredriksson

et al. 2017

SAJIE

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To remove residual stresses, an as-built SLM object is usually posttreated. This treatment can affect the microstructure, changing the final mechanical characteristics. This investigation is focused on the microstructural characterisation of 316L austenitic stainless steel in as-built and annealed conditions. The SLM microstructure was relatively stable up to 900°C, when cell boundaries start to disappear. At higher temperatures, an insignificant grain coarsening was detected. These microstructural changes caused a gradual drop in the hardness. The obtained result is background for the future development of post-treatment regimens to achieve a high level in the final mechanical properties of SLM objects. OPSOMMINGOm die res-spannings in ŉ lasergesinterde metaalvoorwerp te verwyder, word die voorwerp gewoonlik na die tyd behandel. Hierdie behandeling kan die mikrostruktuur beïnvloed, wat kan lei tot ŉ verandering in die meganiese eienskappe. Hierdie ondersoek fokus op die mikrostruktuur karakterisering van 316L austenitiese vlekvrye staal in die soos-vervaardige en uitgegloeide toestande. Die lasergesinterde metaal mikrostruktuur was relatief stabiel tot 900°C, waarna alle selgrense begin verdwyn het. By hoër temperature is onbeduidende grein vergrowwing bespeur. Hierdie mikrostruktuur veranderinge veroorsaak ŉ geleidelike afname in die hardheid van die voorwerp. Dié resultaat skep die basis vir verdere ontwikkeling van die behandeling skedules om ŉ hoë vlak in die finale meganiese eienskappe van lasergesinterde metaalvoorwerpe te verkry.

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“…It is seen (Figure 9a,b) that the cell boundaries were still stable after heat treatment at 800 • C. After heat treatment at 900 • C, the cells were no longer observed (Figure 9c). Similar observations of cell stability have been reported in [62,63]. Colonies, in contrast, were quite stable.…”

Section: Thermal Stabilitysupporting

confidence: 87%

Microstructure, Solidification Texture, and Thermal Stability of 316 L Stainless Steel Manufactured by Laser Powder Bed Fusion

Krakhmalev

Fredriksson

Svensson

et al. 2018

Metals

144

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This article overviews the scientific results of the microstructural features observed in 316 L stainless steel manufactured by the laser powder bed fusion (LPBF) method obtained by the authors, and discusses the results with respect to the recently published literature. Microscopic features of the LPBF microstructure, i.e., epitaxial nucleation, cellular structure, microsegregation, porosity, competitive colony growth, and solidification texture, were experimentally studied by scanning and transmission electron microscopy, diffraction methods, and atom probe tomography. The influence of laser power and laser scanning speed on the microstructure was discussed in the perspective of governing the microstructure by controlling the process parameters. It was shown that the three-dimensional (3D) zig-zag solidification texture observed in the LPBF 316 L was related to the laser scanning strategy. The thermal stability of the microstructure was investigated under isothermal annealing conditions. It was shown that the cells formed at solidification started to disappear at about 800 • C, and that this process leads to a substantial decrease in hardness. Colony boundaries, nevertheless, were quite stable, and no significant grain growth was observed after heat treatment at 1050 • C. The observed experimental results are discussed with respect to the fundamental knowledge of the solidification processes, and compared with the existing literature data.

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Transformation of austenite to duplex austenite-ferrite assembly in annealed stainless steel 316L consolidated by laser melting

Cited by 227 publications

References 16 publications

Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

Study of the effect of heat treatment on fatigue crack growth behaviour of 316L stainless steel produced by selective laser melting

Microstructural and Thermal Stability of Selective Laser Melted 316l Stainless Steel Single Tracks

Microstructure, Solidification Texture, and Thermal Stability of 316 L Stainless Steel Manufactured by Laser Powder Bed Fusion

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