Fatigue and Fracture of Engineering Alloys

2012 ◽  
pp. 209-261
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Grain Size ◽  
Corrosion Damage ◽  
Operating Conditions ◽  
Fracture Properties ◽  
Fatigue And Fracture ◽  
Engineering Alloys ◽  
Accelerate Crack Growth ◽  
Crack Growth Rates

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.

Optimization of Particle Size and Distribution by Hydrostatic Extrusion

2007 ◽  
Vol 561-565 ◽  
pp. 869-872 ◽  
Author(s):  
Małgorzata Lewandowska ◽  
Kinga Wawer
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Aluminium Alloys ◽  
Hydrostatic Extrusion ◽  
Nanometer Scale ◽  
Second Phase ◽  
Size Refinement ◽  
Second Phase Particles ◽  
Fatigue And Fracture

Hydrostatic extrusion (HE) as a method of metals forming is known for about 100 years. Recently, it has been utilized as an efficient way of grain size refinement down to nanometer scale. In the case of engineering metals, HE processing alters not only grain size but also second phase particles such as intermetallic inclusions and precipitates. During HE processing, these particles significantly change their size, shape and spatial distribution. These changes are accompanied by improvement in properties of processed metals such as fatigue and fracture toughness. In the present work, changes of second phase particles induced by HE are described in a quantitative way for aluminium alloys. Their impact on mechanical properties is also discussed.

Microstructural and Mechanical Properties Changes of Silicon Nitride Based Ceramic Using Post-Sintering Heat Treatment

2012 ◽  
Vol 727-728 ◽  
pp. 1085-1091
Author(s):  
José Vitor C. Souza ◽  
O.M.M. Silva ◽  
E.A. Raymundo ◽  
João Paulo Barros Machado
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Fracture Toughness ◽  
Grain Size ◽  
Wear Resistance ◽  
High Hardness ◽  
Gas Pressure ◽  
Low Density ◽  
Nitrogen Gas ◽  
Structural Applications

Si3N4based ceramics are widely researched because of their low density, high hardness, toughness and wear resistance. Post-sintering heat treatments can enhance their properties. Thus, the objective of the present paper was the development of a Si3N4based ceramic, suitable for structural applications, by sintering in nitrogen gas pressure, using AlN, Al2O3, and Y2O3as additives and post-sintering heat treatment. The green bodies were fabricated by uniaxial pressing at 80 MPa with subsequent isostatic pressing at 300 MPa. The samples were sintered at 1900°C for 1 h under N2gas pressure of 0.1 MPa. Post-sintering heat treatment was performed at 1500°C for 48 h under N2gas pressure of 1.0 MPa. From the results, it was observed that after post-sintering heat treatment there was a reduction of α-SiAlON phase and increase of β-Si3N4phase, with consequent changing in grain size, decrease of fracture toughness and increase of the Vickers hardness.

Development of heat treatment parameters to improve fracture toughness and grain size of an embrittled maraging steel

1992 ◽  
Vol 9 (2) ◽  
pp. 125-131 ◽  
Author(s):  
P. P. Sinha ◽  
K. Sreekumar ◽  
N. S. Babu ◽  
B. Pant ◽  
A. Natarajan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Grain Size ◽  
Maraging Steel ◽  
Improve Fracture Toughness

Statistical Model for Prediction of Plate-Specific Fracture Toughness Properties of ASTM A285 Steel

2003 ◽  
Author(s):  
K. H. Subramanian ◽  
B. J. Wiersma ◽  
A. J. Duncan ◽  
S. P. Harris
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Grain Size ◽  
Loading Rate ◽  
Statistical Significance ◽  
Operating Conditions ◽  
Dynamic Strain ◽  
Type I ◽  
Data Set ◽  
Test Matrix

A materials test program was developed to measure mechanical properties of A285 carbon steel under conditions relevant to waste storage tanks at the Savannah River Site. Fracture toughness and tensile testing were performed on ASTM Type A285 steels that span tank plate compositions. Variables relevant to the material and load conditions for Type I and Type II tanks were defined and a statistical test matrix was designed for fracture toughness testing. The test matrix consisted of eight variables expected to influence mechanical properties. The independent variables were carbon content, manganese content, sulfur content, thickness, pearlite fraction, and grain size. The responses were the fracture toughness JIc, and a figure-of-merit at J3mm to allow for sub-critical ductile crack growth. A total of 85 J-R curves were compiled. The full data set was used to construct statistical models to predict fracture properties as a function of metallurgical properties and operating conditions. Eight independent models resulting from combinations of loading rate (quasi-static, dynamic) and orientation (T-L, L-T) were developed. The statistical significance of terms was determined for each of the models. Thickness and grain size were found to be of statistical significance in the models developed for the dynamic strain rate testing data. Compositional variables were found to be of statistical significance for the quasi-static loading rate fracture toughness data.

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
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Fracture Toughness ◽  
Grain Size ◽  
Tensile Properties ◽  
Thick Plate ◽  
Energy Dispersive Spectrometer ◽  
Grain Refiner ◽  
Strain Fracture ◽  
Optical Electron

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.

Solute Partitioning to Enhance Mechanical Properties of Aged Aluminium Alloys

2009 ◽  
Vol 618-619 ◽  
pp. 487-491 ◽  
Author(s):  
Ian J. Polmear ◽  
Roger N. Lumley
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Solid Solution ◽  
Fracture Toughness ◽  
Fatigue Strength ◽  
Aluminium Alloys ◽  
Creep Resistance ◽  
Fracture Properties ◽  
Secondary Precipitation ◽  
The Matrix

Deliberate partitioning of solute elements between the matrix solid solution and dispersed precipitates in aged aluminium alloys can be facilitated by underageing during heat treatment. Although this practice may cause some reduction in tensile properties, it has been shown that significant improvements may be achieved in creep resistance, fatigue strength and fracture toughness. Exploitation of secondary precipitation can allow simultaneous increases to be obtained in tensile and fracture properties.

Fracture Toughness of Nanocrystalline L12 (Al+X at.%Mn)3 Ti Prepared by Mechanical Alloying and Consolidated by SPS

2003 ◽  
Vol 778 ◽  
Author(s):  
Hee Sup Jang ◽  
Chang Won Kang ◽  
Young-Seok Kim ◽  
Seon-Jin Kim
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Grain Size ◽  
Mechanical Alloying ◽  
Sintering Temperature ◽  
Treatment Temperature ◽  
Vacuum Furnace ◽  
Fracture Toughness Test ◽  
Ternary Element ◽  
Mn Concentration

AbstractThe effects of ternary element addition of manganese on microstructure and mechanical properties of nanocrystalline L12 (Al+X at.%Mn)3Ti (X=0 - 12) fabricated by mechanical alloying and spark plasma sintering (SPS) were investigated. The SPS method was used to consolidate nanocrystalline L12 (Al+X at.%Mn)3Ti with the pressure of 50 MPa. The heating rate was 100°C /min. The final sintering temperature was determined from the observation of the shrinkage of the specimen. In binary Al3Ti, the final sintering temperature was 864°C. The sintering temperature was reduced down to 658°C with increasing Mn concentration. After SPS, the L12 structure was maintained in the specimens which contained Mn concentration of 8- 12 at.%. The microhardness test, grain size measurements, and fracture toughness test were conducted as a function of Mn concentration. In order to investigate the effect of the grain size on the microhardness and fracture toughness of the (Al+8 at.%Mn)3Ti, heat treatments were performed in a vacuum furnace ( 10-3 torr ). With increasing heat treatment temperature, the microhardness decreased due to the formation and growth of Al4C3, Al2O3, and TiC, while fracture toughness increased. The fracture toughness of 4.12 MPa m1/2 was attained for the (Al+8 at.%Mn)3Ti specimen and it was the highest value among the specimens after 1h heat treatment at 1100°C. The grain sizes were about 60 nm and 100 nm after 1 h heat treatment at 900°C and 1100°C, respectively.

Microstructure and Properties of Reaction-Formed Silicon Carbide

2007 ◽  
Vol 280-283 ◽  
pp. 1271-1274 ◽  
Author(s):  
Yan Xiang Wang ◽  
Shou Hong Tan ◽  
Dong Liang Jiang
Keyword(s):  
Heat Treatment ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Grain Size ◽  
Corrosion Resistance ◽  
Microstructure And Properties ◽  
Bonding Area ◽  
Si Content

The effects of microstructure on strength, toughness and corrosion resistance of reactionformed silicon carbide and heat treatment on the properties of reaction-formed silicon carbide have been investigated in this paper. The results show strength and corrosion resistance of reaction-formed silicon carbide decrease with increasing Si content. Fracture toughness shows no rule with free Si content. The average SiC grain size and bonding area of SiC grain increase during heat treatment at 1850°C. The strengths of the samples after heat treatment decrease compared with that of the samples before heat treatment due to the pores in the heat treatment bodies.

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