Static Crack Resistance Research Articles

Calculating the static cracking resistance of the fusion zone of 15Kh2NMFA steel and austenitic deposits

Calculating the static cracking resistance of the fusion zone of 15Kh2NMFA steel and austenitic deposits

Role of the adsorption factor in reduction of the long-term static crack resistance of high-strength steel in gaseous media

The purpose of this work was to establish the role of the adsorption layer in subcritical crack growth in high-strength steel subject to long-term static loading in controlled-composition gaseous media. Investigations of long-term crack resistance were made in a sealed chamber on 45KhN2MFA steel with an edge crack loaded by four-point bending. The gaseous media were commercially pure hydrogen and helium. The most aggressive medium was deoxygenated and dried hydrogen and the least aggressive helium. The effect of helium moisture content on crack growth kinetics was evaluated. Subcritical crack growth mechanisms were determined, by fractography with a scanning electron microscope, to be typically intergranular. Hydrogen embrittlement occurred in three stages: establishment of adsorption equilibrium, adsorbed molecule dissociation into atomic hydrogen, and transport of hydrogen atoms into the prefailure zone. Local fracture occurred as a result of a reduction in critical stress in connection with hydrogen impregnation of the prefailure zone.

Special features of the method of determining static cracking resistance of cast irons

Special features of the method of determining static cracking resistance of cast irons

Static cracking resistance of welded joints with misaligned edges

Static cracking resistance of welded joints with misaligned edges

Stress corrosion resistance of a steel used for the vessels (frames) of water-moderated power reactors (WMPR)

The static crack resistance of 15Kh2MFA steel in a corrosive medium directly under conditions of neutron irradiation or of operational temperatures and pressures was studied. Samples were stressed in the off-center tension mode, subsequently held either in the core of an experimental reactor or in an autoclave, and finally loaded at room temperature up to fracture. Preliminary heat treatments were conducted. The samples were irradiated after being placed in the coolant of the core of an IRT-2000 reactor. Results indicate the absence of corrosion crack growth in the steel at given neutron flux densities, temperatures, and pressures. The fracture toughness increased with increasing stress intensity when stressing the steel specimens and subsequently holding them in the coolant medium.

Crack resistance of rolled semiproducts made of alloys of the system Al-Cu-Mg in different structural states

1. An increase of the volume fraction of particles of excess phase from 1 to 2.7\2-3.5% leads to a decrease of Kcy by 5\2-10% and an increase of the growth rate of the fatigue crack by a factor of 1.5\2-2 for \gDK=850\2-1000 N/mm3/2. When the volume fraction of excess phases is 4.5%, the growth rate of the fatigue crack increases even with low values of ΔK. 2. In comparison with natural aging, artificial aging leads to reduced characteristics of static crack resistance and increased growth rate of the fatigue crack in the entire investigated range of \gDK. 3. The use of thermomechanical treatment in the production of rolled plates makes it possible to increase the strength properties approximately by 10% while the rupture work of the specimen with crack is reduced and the growth rate of the fatigue crack increases.

Effect of bucking on static crack resistance

Effect of bucking on static crack resistance

The static crack resistance of the material of large back-up rolls for rolling mills at increased temperatures

The static crack resistance of the material of large back-up rolls for rolling mills at increased temperatures

Method used and results obtained in the investigation of crack resistance of some brittle nonmetallic materials

1. The author describes the methodical features of the determination of the crack resistance of BNM materials in testing flat specimens for transverse compression and eccentric tension. 2. The characteristics of static KIo, quasistatic KIo, and quasidynamic KIc crack resistance of glass, porcelain, and glassceramic are determined. 3. For the material being investigate the characteristics KIo, KIi and KIc can be determined by testing a single specimen first for transverse compression and then for eccentric tension.

Influence of inhibitors in static corrosion crack resistance tests of 40Kh steel specimens

Influence of inhibitors in static corrosion crack resistance tests of 40Kh steel specimens

Comparative evaluation of the load-bearing capacity of shell structures in engineering by the parameters of static and cyclic crack resistance

Comparative evaluation of the load-bearing capacity of shell structures in engineering by the parameters of static and cyclic crack resistance

Certain methodological aspects of determination of the static corrosion crack resistance of structural materials

Certain methodological aspects of determination of the static corrosion crack resistance of structural materials

Static crack resistance of a structural element with a small crack

Static crack resistance of a structural element with a small crack

Static corrosion crack resistance of heat-resistant vessel steels and their weld joints

Static corrosion crack resistance of heat-resistant vessel steels and their weld joints

The kinetics and mechanism of fatigue crack growth in iron

pbetween the evolution of the dislocation structure of iron during fatigue and the micromechanism of fracture in the stage of subcritical crack growth. Special attention was devoted to consideration of the role of the dislocation substructure in the formation of the threshold values of the stress intensity factor AKth. Preliminary cold plastic deformation by rolling was selected as an additional factor of the substructure action. The Materials and Method of the Investigation. The investigations were made on samples of technical purity iron containing 0.035% C and 0.18% Mn. The pieces were annealed at 920~ for 2 h, after which a portion of them was cold rolled with deformations of 25 and 50%. All of the pieces were machined to obtain samples of the required dimensions. The tests, made at room temperature, included obtaining full fatigue fracture curves, static crack resistance tests (the parameter Klc), and standard tensile tests of 15 x 18 x 200 mm beam samples in cyclic loading with a frequency of 8.3 Hz and a cycle assymetry of R = 0. The samples for determining static crack resistance and the strength properties were prepared from halves of samples obtained after the fatigue tests. The J-integral method was used to determine the fracture toughness Klc and the value of Jlc was calculated using the known method [i] taking into consideration the recommendations in [2]. Subsequently, the values of Jlc were converted to Klc using the relationship Jlc = (l--v2)'K~c/E" The properties of shortterm strength and ductility were determined in tension of cylindrical samples with a gage length diameter of 5 mm. The fracture surfaces of samples tested in static and cyclic crack resistance were investigated on a JXA-50A scanning microscope. The dislocation structure of samples subjected to cyclic loading was studied with the use of a Tesla BS-613 transmission electron microscope on thin foils cut by the electrospark method directly from the layer under the fracture surface and also from deeper layers of samples. The first cut was made at a depth of not more than 0.3 mm from the surface of the fracture and then the foil was thinned from the side opposite the fracture surface. The processes of slip band development and the

Application of the R-Curve Concept to Fatigue Crack Growth

Crack growth resistance for both static (rising load) and for cyclic fatigue crack growth has been shown to be a continuous function over a range of 0.1 μm to 10 cm in crack extension for 2024-T3 aluminum. Crack growth resistance to each fatigue cycle of crack extension is shown to approach the materials ordinary undirectional static crack resistance value when the cyclic stress ratio is zero. The fatigue crack extension is averaged over many cycles and is correlated with the maximum value of the crack tip stress intensity, Kmax. A linear plot of crack growth resistance for fatigue and static loading data shows similar effects of thickness, stress ratio, and other parameters. The effect of cyclic stress ratio on crack growth resistance for 2219 aluminum indicates the magnitude of differences in resistance when plotted to a linear scale. Prediction of many of these trends is possible using one of several available crack growth data correlating techniques. It appears that a unique resistance curve, dependent on material, crack orientation, thickness, and stress/physical environment, can be developed for crack extensions as small as 0.076 μm (3 μ inches). This wide range, crack growth resistance curve is seen of immense potential for use in both fatigue and fracture studies.