Tensile Deformation Behavior of Typical Porous Laminate Structure at Different Temperatures

In this study, the Ni-Cr-W superalloy GH3230 is used as the test material. According to the actual structure of the flame tube, a porous laminate structure specimen is designed. The structure consists of impact holes, overflow holes and pin fins. High-temperature tensile tests at 650 °C, 750 °C and 850 °C were carried out to study the high-temperature mechanical properties and fracture mechanism of the specimens of porous laminate structure, and the strain nephogram of the specimens were obtained by digital image correlation (DIC) technique. Due to the large number and dense arrangement of overflow holes, an obvious hole interference effect can be found from the strain nephogram. The stress concentration around the pore and the interference between the pores provide priority places and paths for the initiation and propagation of microcracks. The test found that the microcracks of the porous laminate structure first occurred around the hole, the overflow surface fractured first, after which the impact surface fractured. The strength of the alloy exhibits a significant temperature sensitivity to temperature. From 650 °C to 750 °C, the ultimate strength (σb) and yield strength (σ0.2) decrease slightly, but they decrease significantly at 850 °C. The microstructure of the fracture surface shows that all microcracks occur at the interface between the matrix and the carbides but that the fracture mode of the specimens gradually changes from intergranular fracture to transgranular fracture as the temperature increases. Due to the pinning effect of the intracrystalline diffusive solute atoms on the dislocations, the stress-strain curves of the high-temperature tensile tests at 650 °C and 750 °C showed zigzag characteristic fluctuations during the strengthening stage.

Download Full-text

Microstructures and High Temperature Tensile Properties of As-Aged Mg-6Zn-1Mn-4Sn-(01, 0.5 and 1.0) Y Alloys

Metals ◽

10.3390/met9010001 ◽

2018 ◽

Vol 9 (1) ◽

pp. 1 ◽

Cited By ~ 4

Author(s):

Guangshan Hu ◽

Meipeng Zhong ◽

Changfa Guo

Keyword(s):

Electron Microscopy ◽

High Temperature ◽

Tensile Properties ◽

Fracture Mechanism ◽

Tensile Tests ◽

Mixed Mode Fracture ◽

Transgranular Fracture ◽

Fracture Type ◽

High Temperature Tensile ◽

High Temperature Tensile Properties

The microstructures and high-temperature tensile properties of as-aged Mg-6Zn-1Mn-4Sn-(0.1, 0.5 and 1.0) Y (wt.%, ZMT614-Y) alloys were investigated by optical microscopy (OM), X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-temperature tensile tests. The tensile temperatures were 150 °C, 200 °C, 250 °C and 300 °C, respectively. The results showed that the phase compositions of as-aged alloys were α-Mg, α-Mn, MgZn2, Mg2Sn, and MgSnY phases. The Mg2Sn and MgSnY high-temperature phases inhibited grain growth in the heat treatment and tensile processes. The as-aged ZMT614-0.5Y alloy has the best high-temperature mechanical properties, with yield strength (YS), ultimate tensile strength (UTS), and elongation values of 277 MPa, 305 MPa, and 16.7%, respectively, at 150 °C. As the tensile temperature increased to 300 °C, the YS and UTS decreased to 136 MPa and 150 MPa, and elongation increased to 25.5%. The fracture mechanism changed as the tensile temperatures ranged from 150 °C to 300 °C, from the transgranular fracture type at temperatures of 150 °C and 200 °C, to the transgranular and intergranular mixed-mode fracture type when tensile temperatures increased to 250 °C, to an intergranular fracture mechanism at 300 °C.

Download Full-text

High Temperature Tensile Tests of Welded Mild Steel and 18/8 Stainless Steel

Transactions of the Japan Society of Mechanical Engineers ◽

10.1299/kikai1938.18.71_31 ◽

1952 ◽

Vol 18 (71) ◽

pp. 31-34

Author(s):

Hiroshi TENKUMO ◽

Atsushi HASUI ◽

Tatsuo SAITO

Keyword(s):

Stainless Steel ◽

High Temperature ◽

Mild Steel ◽

Tensile Tests ◽

High Temperature Tensile

Download Full-text

Strength Enhancement of Superduplex Stainless Steel Using Thermomechanical Processing

Metals ◽

10.3390/met11071094 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1094

Author(s):

M. A. Lakhdari ◽

F. Krajcarz ◽

J. D. Mithieux ◽

H. P. Van Landeghem ◽

M. Veron

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Thermomechanical Processing ◽

Tensile Tests ◽

Image Correlation ◽

Strength Enhancement ◽

Industrial Material ◽

Superduplex Stainless Steel ◽

The Impact ◽

Strength Improvement

The impact of microstructure evolution on mechanical properties in superduplex stainless steel UNS S32750 (EN 1.4410) was investigated. To this end, different thermomechanical treatments were carried out in order to obtain clearly distinct duplex microstructures. Optical microscopy and scanning electron microscopy, together with texture measurements, were used to characterize the morphology and the preferred orientations of ferrite and austenite in all microstructures. Additionally, the mechanical properties were assessed by tensile tests with digital image correlation. Phase morphology was not found to significantly affect the mechanical properties and neither were phase volume fractions within 13% of the 50/50 ratio. Austenite texture was the same combined Goss/Brass texture regardless of thermomechanical processing, while ferrite texture was mainly described by α-fiber orientations. Ferrite texture and average phase spacing were found to have a notable effect on mechanical properties. One of the original microstructures of superduplex stainless steel obtained here shows a strength improvement by the order of 120 MPa over the industrial material.

Download Full-text

Mechanical Properties of Spruce Wood Extracted from GLT Beams Loaded by Fire

Sustainability ◽

10.3390/su13105494 ◽

2021 ◽

Vol 13 (10) ◽

pp. 5494

Author(s):

Lucie Kucíková ◽

Michal Šejnoha ◽

Tomáš Janda ◽

Jan Sýkora ◽

Pavel Padevět ◽

...

Keyword(s):

Mechanical Properties ◽

High Temperature ◽

Cross Section ◽

Negative Impact ◽

Tensile Tests ◽

Thermal Recovery ◽

Bending Test ◽

Small Scale ◽

Spruce Wood ◽

The Impact

Heating wood to high temperature changes either temporarily or permanently its physical properties. This issue is addressed in the present contribution by examining the effect of high temperature on residual mechanical properties of spruce wood, grounding on the results of full-scale fire tests performed on GLT beams. Given these tests, a computational model was developed to provide through-thickness temperature profiles allowing for the estimation of a charring depth on the one hand and on the other hand assigning a particular temperature to each specimen used subsequently in small-scale tensile tests. The measured Young’s moduli and tensile strengths were accompanied by the results from three-point bending test carried out on two groups of beams exposed to fire of a variable duration and differing in the width of the cross-section, b=100 mm (Group 1) and b=160 mm (Group 2). As expected, increasing the fire duration and reducing the initial beam cross-section reduces the residual bending strength. A negative impact of high temperature on residual strength has also been observed from simple tensile tests, although limited to a very narrow layer adjacent to the charring front not even exceeding a typically adopted value of the zero-strength layer d0=7 mm. On the contrary, the impact on stiffness is relatively mild supporting the thermal recovery property of wood.

Download Full-text