Case Study of the Tensile Fracture Investigation of Additive Manufactured Austenitic Stainless Steels Treated at Cryogenic Conditions

Bidulský, Róbert; Bidulská, Jana; Gobber, Federico Simone; Kvačkaj, Tibor; Petroušek, Patrik; Grande, Marco Actis; Weiss, Klaus-Peter; Manfredi, Diego

doi:10.3390/ma13153328

Cited by 48 publications

(52 citation statements)

References 33 publications

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“…Furthermore, software at the meso-dimensional level must be able to define the steel’s final properties, not only its structural and mechanical character but also its exact geometrical dimensions and shapes [ 110 ]. Nowadays, structure refinement is an attractive way to increase the strength properties of steels using the laser-powder bed fusion process [ 111 , 112 , 113 , 114 ].…”

Section: Resultsmentioning

confidence: 99%

Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Kvačkaj

Bidulská

Bidulský³

2021

Materials

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This review paper concerns the development of the chemical compositions and controlled processes of rolling and cooling steels to increase their mechanical properties and reduce weight and production costs. The paper analyzes the basic differences among high-strength steel (HSS), advanced high-strength steel (AHSS) and ultra-high-strength steel (UHSS) depending on differences in their final microstructural components, chemical composition, alloying elements and strengthening contributions to determine strength and mechanical properties. HSS is characterized by a final single-phase structure with reduced perlite content, while AHSS has a final structure of two-phase to multiphase. UHSS is characterized by a single-phase or multiphase structure. The yield strength of the steels have the following value intervals: HSS, 180–550 MPa; AHSS, 260–900 MPa; UHSS, 600–960 MPa. In addition to strength properties, the ductility of these steel grades is also an important parameter. AHSS steel has the best ductility, followed by HSS and UHSS. Within the HSS steel group, high-strength low-alloy (HSLA) steel represents a special subgroup characterized by the use of microalloying elements for special strength and plastic properties. An important parameter determining the strength properties of these steels is the grain-size diameter of the final structure, which depends on the processing conditions of the previous austenitic structure. The influence of reheating temperatures (TReh) and the holding time at the reheating temperature (tReh) of C–Mn–Nb–V HSLA steel was investigated in detail. Mathematical equations describing changes in the diameter of austenite grain size (dγ), depending on reheating temperature and holding time, were derived by the authors. The coordinates of the point where normal grain growth turned abnormal was determined. These coordinates for testing steel are the reheating conditions TReh = 1060 °C, tReh = 1800 s at the diameter of austenite grain size dγ = 100 μm.

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Section: Resultsmentioning

confidence: 99%

Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Kvačkaj

Bidulská

Bidulský³

2021

Materials

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“…Porosity roughly represents the fraction of void volume over total volume. Pore structures like pore size, morphology, and distribution of porosity within the pressed part present critical items in the load-bearing sections, which means the primary controlling mechanism of the mechanical properties [29][30][31][32].…”

Section: Porositymentioning

confidence: 99%

Innovative Densification Process of a Fe-Cr-C Powder Metallurgy Steel

Gobber

Bidulská

Fais³

et al. 2021

Metals

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In this study, the efficacy of an innovative ultra-fast sintering technique called electro-sinter-forging (ESF) was evaluated in the densification of Fe-Cr-C steel. Although ESF proved to be effective in densifying several different metallic materials and composites, it has not yet been applied to powder metallurgy Fe-Cr-C steels. Pre-alloyed Astaloy CrM powders have been ad-mixed with either graphite or graphene and then processed by ESF. By properly tuning the process parameters, final densities higher than 99% were obtained. Mechanical properties such as hardness and transverse rupture strength (TRS) were tested on samples produced by employing different process parameters and then submitted to different post-treatments (machining, heat treatment). A final transverse rupture strength up to 1340 ± 147 MPa was achieved after heat treatment, corresponding to a hardness of 852 ± 41 HV. The experimental characterization highlighted that porosity is the main factor affecting the samples’ mechanical resistance, correlating linearly with the transverse rupture strength. Conversely, it is not possible to establish a similar interdependency between hardness and mechanical resistance, since porosity has a higher effect on the final properties.

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“…Images also displayed elongated voids bordered with the fibrous network which are phenomena for representing strengthening characteristics, as reported by Malhotra et al [ 26 ]. Robert et al [ 27 ] who studied the CT austenitic stainless steel fracture behavior has stated that the fracture path is mixed, through inter and intra particles and in the same area very different behaviors can coexist. Figure 15 b shows the presence of mixed mode of fracture and Figure 15 c shows the presence of second phase particles in the fracture zone.…”

Section: Tensile Test Digital Image Correlation Fractography Anmentioning

confidence: 99%

Digital Image Correlation of Tensile Properties for Monel 400/SS 316L Dissimilar Metal Welding Joints

et al. 2021

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Dissimilar metal weld joints of Monel 400 and Stainless Steel 316L stainless steel were carried out using Gas Tungsten Arc Welding (GTAW). Conventional annealing and cryogenic treatment were performed on the welded joints. Weld joints of this combination of materials have enormous potential applications in power industry and the available related literature is limited. In the present study, the tensile properties of heat treated (HT), cryotreated (CT), and untreated (UT) specimens were studied. The engineering stress and strain were determined experimentally as per Standard Test Methods for Tension Testing of Metallic Materials (ASTM E8). The strain distribution was evaluated at different zones of weld joint was evaluated using Digital Image Correlation (DIC). Significant difference was noticed between the zones. Weld zone of all samples had less local stress and strain and SS 316L heat affected zone (HAZ) zone had more local stress and strain when compared to other zones. The local strain distribution along distance from weld center line and local stress-strain curves of different zones are also predicted. Scanning Electron Microscopy was used to analyze the fracture behavior of welded samples for HT, CT, and UT specimens.

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Case Study of the Tensile Fracture Investigation of Additive Manufactured Austenitic Stainless Steels Treated at Cryogenic Conditions

Cited by 48 publications

References 33 publications

Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Overview of HSS Steel Grades Development and Study of Reheating Condition Effects on Austenite Grain Size Changes

Innovative Densification Process of a Fe-Cr-C Powder Metallurgy Steel

Digital Image Correlation of Tensile Properties for Monel 400/SS 316L Dissimilar Metal Welding Joints

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