Fracture toughness

About: Fracture toughness is a research topic. Over the lifetime, 39642 publications have been published within this topic receiving 854338 citations.

Microstructure and Mechanical Properties of Porous Alumina Ceramics Fabricated by the Decomposition of Aluminum Hydroxide

Abstract: The mechanical properties of Al2O3-based porous ceramics fabricated from pure Al2O3 powder and the mixtures with Al(OH)3 were investigated. The fracture strength of the porous Al2O3 specimens sintered from the mixture was substantially higher than that of the pure Al2O3 sintered specimens because of strong grain bonding that resulted from the fine Al2O3 grains produced by the decomposition of Al(OH)3. However, the elastic modulus of the porous Al2O3 specimens did not increase with the incorporation of Al(OH)3, so that the strain to failure of the porous Al2O3 ceramics increased considerably, especially in the specimens with high porosity, because of the unique pore structures related to the large original Al(OH)3 particles. Fracture toughness also increased with the addition of Al(OH)3 in the specimens with higher porosity. However, fracture toughness did not improve in the specimens with lower porosity because of the fracture-mode transition from intergranular, at higher porosity, to transgranular, at lower porosity.

Fracture Toughness of Human Dentin

Abstract: Plane strain fracture toughness (KIC) was determined for coronal dentin using compact tension test-pieces obtained from recently extracted permanent lower molar teeth. Specimens were prepared and tested such that the moving crack front was aligned parallel to the tubule orientation. The fracture toughness (K IC) was temperature-invariant in the range 0-60°C, and the mean value obtained was 3.08 MN.(m)-1.5 (SD: 0.33). The critical strain energy release rate (GIC) of dentin was also calculated utilizing modulus data and was found to increase slightly with temperature, possibly as a consequence of significant temperature-dependence of the modulus:The fracture toughness of dentin is midway in the range (0.23- 6.56) observed for cortical bone and is a factor of two greater than that exhibited by most current restorative materials.

Effect of 475 ◦ C embrittlement on the mechanical properties of duplex stainless steel

Abstract: The binary iron–chromium alloy embrittles in the temperature range of 280–500 °C limiting its applications to temperatures below 280 °C. The embrittlement is caused by the decomposition of the alloy to chromium-rich phase, α′ and iron-rich phase, α. This phenomenon is termed 475 °C embrittlement as the rate of embrittlement is highest at 475 °C. Primarily the investigations on 475 °C embrittlement were confined to binary iron–chromium alloys and ferritic stainless steels. Duplex stainless steel grades contain varying proportions of ferrite and austenite in the microstructure and the ferritic phase is highly alloyed. Moreover, this grade of steel has several variants depending on the alloy composition and processing route. This modifies the precipitation behaviour and the resulting change in mechanical properties in duplex stainless steels when embrittled at 475 °C as compared to binary iron chromium systems. The precipitation behaviour of duplex stainless steel at 475 °C and the effect on tensile, fracture and fatigue behaviour are reviewed in this article.

Experimental Verification of the J Ic and Equivalent Energy Methods for the Evaluation of the Fracture Toughness of Steels

Abstract: The critical value J 1 c and the apparent fracture toughness K B d are measured with a single small specimen (compact tension or three-point-bend bar) loaded in the elastic-plastic range. Initiation is detected during loading by an electrical potential method. For the steels studied here (2.25Cr-lMo, electroslag weld, manganese cast steel), the K 1 c values deduced from J 1 c are in agreement with the K 1 c values directly measured with thick specimens in the transition-temperature range. Furthermore, the equivalent energy procedure gives the same results as those obtained by the J-integral method.