scholarly journals Effect of Grain Refiner on Fracture Toughness of 7050 Ingot and Plate

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6705
Author(s):  
Fang Yu ◽  
Xiangjie Wang ◽  
Tongjian Huang ◽  
Daiyi Chao

In this paper, two types of grain refining alloys, Al-3Ti-0.15C and Al-5Ti-0.2B, were used to cast two types of 7050 rolling ingots. The effect of Al-3Ti-0.15C and Al-5Ti-0.2B grain refiners on fracture toughness in different directions for 7050 ingots after heat treatment and 7050-T7651 plates was investigated using optical electron microscopy (OEM) and scanning electron microscopy (SEM). Mechanical properties testing included both tensile and plane strain fracture toughness (KIC). The grain size was measured from the surface to the center of the 7050 ingots with two different grain refiners. The fracture surface was analyzed by SEM and energy dispersive spectrometer (EDS). The experiments showed the grain size from edge to center was reduced in 7050 ingots with both the TiC and TiB refiners, and the grain size was larger for ingots with the Al-3Ti-0.15C grain refiner at the same position. The tensile properties of 7050 ingots after heat treatment with Al-3Ti-0.15C grain refiner were 1–2 MPa lower than the ingot with the Al-5Ti-0.2B grain refiner. For the 7050-T7651 100 mm thick plate with the Al-3Ti-0.15C grain refiner, for the L direction, the tensile properties were lower by about 10~15 MPa; for the plate with the Al-3Ti-0.15C refiner than plate with Al-5Ti-0.2B refiner, for the LT direction, the tensile properties were lower by about 13–18 MPa; and for the ST direction, they were lower by about 8–10 MPa compared to that of Al-5Ti-0.2B refiner. The fracture toughness of the 7050-T7651 plate produced using the Al-3Ti-0.15C ingot was approximately 2–6 MPa · m higher than the plate produced from the Al-5Ti-0.2B ingot. Fractography of the failed fracture toughness specimens revealed that the path of crack propagation of the 7050 ingot after heat treatment produced from the Al-3Ti-0.15C grain refiner was more tortuous than in the ingot produced from the Al-5Ti-0.2B, which resulted in higher fracture toughness.

Alloy Digest ◽  
1964 ◽  
Vol 13 (7) ◽  

Abstract Cooper Alloy 14S is an abrasion, heat and corrosion resistant alloy steel containing 12% chromium. It can be hardened by heat treatment. It is recommended for pumps and valves in the cast form. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: SS-158. Producer or source: Cooper Alloy Corporation.


Alloy Digest ◽  
1971 ◽  
Vol 20 (8) ◽  

Abstract ABRASALLOY No. 3 is a space-age composite alloy steel developed to provide a unique combination of strength, ductility and abrasion resistance for earth-moving, mineral processing and mining machinery. It is not available in any other plate manufactured by conventional rolling and heat treatment. This datasheet provides information on composition, hardness, elasticity, tensile properties, and shear strength as well as fracture toughness. It also includes information on forming, heat treating, machining, and joining. Filing Code: SA-267. Producer or source: Atlantic Steel Corporation.


Alloy Digest ◽  
1963 ◽  
Vol 12 (6) ◽  

Abstract ALLEGHENY METAL 350 is a chromium-nickel-molybdenum stainless steel developed to bridge the gap between the 300 and 400 series. It can be hardened by heat treatment. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-29. Producer or source: Allegheny Ludlum Corporation. Originally published May 1955, revised June 1963.


2012 ◽  
pp. 209-261

Abstract This chapter provides information and data on the fatigue and fracture properties of steel, aluminum, and titanium alloys. It explains how microstructure, grain size, inclusions, and other factors affect the fracture toughness and fatigue life of these materials and the extent to which they can be optimized. It also discusses the effect of metalworking and heat treatment, the influence of loading and operating conditions, and factors such as corrosion damage that can accelerate crack growth rates.


1989 ◽  
Vol 4 (2) ◽  
pp. 248-256 ◽  
Author(s):  
T. M. Shaw ◽  
S. L. Shinde ◽  
D. Dimos ◽  
R. F. Cook ◽  
P. R. Duncombe ◽  
...  

We have used transmission electron microscopy and optical microscopy to examine the effect that grain size and heat treatment have on twinning and microcracking in polycrystalline Y1Ba2Cu3O7−δ. It is shown that isothermal oxygenation heat treatments produce twin structures consisting of parallel twins, with a characteristic spacing that increases with increasing grain size. Slow cooling through the temperature range where the orthorhombic-to-tetragonal transformation induces twinning, however, produces a structure consisting of a hierarchical arrangement of intersecting twins, the scale of which appears to be independent of grain size. It is also shown that the microcracking induced by anisotropic changes in grain dimensions on cooling or during oxygenation can be suppressed if the grain size of the material is kept below about 1 μm. The results are examined in the light of current models for transformation twinning and microcracking and the models used to access the effect other processing variables such as oxygen content, doping or heat treatment may have on the microstructure of Y1Ba2Cu3O7−δ.


Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 643
Author(s):  
Chiara Soffritti ◽  
Annalisa Fortini ◽  
Ramona Sola ◽  
Elettra Fabbri ◽  
Mattia Merlin ◽  
...  

Towards the end of the last century, vacuum heat treatment of high speed steels was increasingly used in the fabrication of precision cutting tools. This study investigates the influence of vacuum heat treatments at different pressures of quenching gas on the microstructure and mechanical properties of taps made of M35 high speed steel. Taps were characterized by optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction, apparent grain size and Vickers hardness measurements, and scratch tests. Failure analysis after tapping tests was also performed to determine the main fracture mechanisms. For all taps, the results showed that microstructures and the values of characteristics of secondary carbides, retained austenite, apparent grain size and Vickers hardness were comparable to previously reported ones for vacuum heat treated high speed steels. For taps vacuum heat treated at six bar, the highest plane strain fracture toughness was due to a higher content of finer small secondary carbides. In contrast, the lowest plane strain fracture toughness of taps vacuum heat treated at eight bar may be due to an excessive amount of finer small secondary carbides, which may provide a preferential path for crack propagation. Finally, the predominant fracture mechanism of taps was quasi-cleavage.


2016 ◽  
Vol 30 (1) ◽  
pp. 24-37 ◽  
Author(s):  
Hongyu Wang ◽  
Tao Sun ◽  
Cong Peng ◽  
Zhanjun Wu

Epoxy-based composites containing silica modified by various silane coupling agents (SCAs) were prepared. The effect of the SCAs and the silica content on the thermal, mechanical properties, and fracture toughness of the nanocomposites was investigated. The particle size and dispersion state of the modified silica particles in the matrix were determined by transmission electron microscopy. The modification of silica with SCAs was verified by Fourier transform infrared spectroscopy. The specific tensile properties at ambient temperature (AT, 298 K) were compared with those at cryogenic (LT, 77 K) condition for silica content of 1−5 wt%. The effect of certain types of coupling agents on the thermal properties of the composites was also investigated. The Tg of all amino-silane-modified composites tended to be improved at low silica contents, while that of epoxy-silane-modified composites seemed to be enhanced further at high silica content. The tensile properties of the nanocomposites both at AT and LT tended to be enhanced at lower silica content, especially the failure strain. The fracture toughness ( KIC) turned out to be better enhanced by coupling agents at LT. The difference of the toughening mechanism at AT and LT was examined according to the morphology of the fracture surfaces using the scanning electron microscopy.


Author(s):  
R. Padmanabhan ◽  
W. E. Wood

Utilization of high austenitization temperatures to improve fracture toughness of UHSLA steels at similar strength levels has received considerable interest. However, these heat treatments result in reduced ductility and impact toughness. This inverse response of impact and plane strain fracture toughness is essentially due to microstructural effects and it is possible to achieve simultaneous improvements in all these properties through controlled variations in the microstructure.A vacuum remelted Si-modified 4340 steel was chosen for this study under three heat treated conditions, viz., conventional, high temperature and step with austenitization temperatures of 1143 K (1 hr), 1473 K (1 hr) and 1473 K (1 hr) furnace cooled to 1143 K (5 min), respectively. All samples were quenched in oil and tempered at 553 K (1 hr). A modified conventional heat treatment was also designed to achieve a desired microstructure with a 1143 K (1 hr) austenitization, a 923 K (1 hr) intermediate temper (after oil quenching), a 1123 K (3 min) reaustenitization and a final 553 K (1 hr) temper (after requenching) steps.


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