Brittle Fracture Of Steel Research Articles

CHANGE OF MECHANICAL PROPERTIES OF ARCTIC PIPELINES

Background Since the active development of the North has been started recently, there are few experimental data on the operation of pipelines. In this regard, there is a need to assess the current state of pipelines and predict their residual life. Long-term operation of pipelines leads not only to the appearance of defects in the micro-structure, but also to a change in the mechanical properties of the pipe metal. Durability of pipelines should be ensured at all stages of their life cycle. Aims and Objectives Development of recommendations for a quantitative assessment of the mechanical properties of metal pipes of long-running pipelines in the Arctic. Results As a result of the analysis, recommendations are given on the use of pipes for arctic conditions. Based on the existing regulatory documentation, at the stage of designing and manufacturing pipe products, only the level of ductility of the metal in the initial state is set according to the value of impact strength. However, the use of only one indicator as the main characteristic of resistance to brittle fracture of steels in the manufacture of pipes, as practice and numerous studies show, does not guarantee trouble-free operation of pipelines. It is noted that reliable operation of Arctic pipelines is ensured by high fracture toughness and resistance of the pipe metal to crack initiation, slowed down to dangerous dimensions, however, a complete solution to the important problem of trouble-free operation of trunk pipelines requires the development of new principles for the quantitative assessment of mechanical properties (for example, crack resistance) of metal pipes in long-running pipelines in the Arctic.

Фрактографічне обґрунтування втрати опору крихкому руйнуванню сталі після експлуатації в елементах морського портального крана

Фрактографічне обґрунтування втрати опору крихкому руйнуванню сталі після експлуатації в елементах морського портального крана

建築鉄骨分野における最近の動き 建築鉄骨の脆性破壊防止のための破壊力学的アプローチ

建築鉄骨分野における最近の動き 建築鉄骨の脆性破壊防止のための破壊力学的アプローチ

Brittle fracture of steel welded structures used in the north of Russia

Brittle fracture of steel welded structures used in the north of Russia

Brittle fracture of steel with a high phosphorous concentration

The effects of phosphorous segregation on the properties of steels containing two types of globular cementite: (1) preferential distribution at the grain boundaries, and (2) uniform distribution within the grains, have been studied. It is shown that the brittle strength of the investigated steels depends only upon the particle size of the cementite, and is independent of the phosphorous concentration. The brittleness of the steels was evaluated by an original method proposed by Yu. Ya. Meshkov.

The influence of tin inclusions on the brittle fracture of steel

1. With an increase in their volume content from ∼0.01 to ∼0.11% in type 06-14G2AF fine grained low-alloy steel with carbonitride hardening titanium nitride inclusions with an average size of 0.8–1.4 μm have little influence on the yield and flow stress, do not reduce the characteristics of brittle fracture resistance (ψ, eK, SK), but do significantly increase (by an average of 49–63°C) the ductile-to-brittle transition temperature in dynamic bend testing. 2. The reduction in cold resistance may be explained by participation of fractured TiN particles in initiation of formation of cleavage microcracks, elementary acts of discrete brittle fracture. This participation bears a statistical character and (at the maximum investigated inclusion content) to it is related the formation of 30–50% of the cleavage microsources. 3. With the use of the force criterion of brittle fracture it was shown that to the increase in the ductile-to-brittle transition temperature caused by TiN particles corresponds a mean-statistical reduction in microcleavage resistance to 0.73 of the original value. In the microvolumes weakened by particles the microcleavage resistance drops to an average of 0. 32 of the original value, which quantitatively agrees well with the Griffiths crack length, exceeding the average inclusion size. 4. The negative influence of TiN inclusions on cold resistance must be taken into consideration in the use of titanium for alloying and deoxidation and also in the case of its presence as an impurity.

Brittle fracture of steel electrolytically saturated with hydrogen

Brittle fracture of steel electrolytically saturated with hydrogen

Ductile and brittle fracture of steel

Ductile and brittle fracture are distinguished by the condition of the fracture surface. A typical example of brittle fracture is the absence of traces of plastic deformation on the fracture surface. For all metals, especially bcc and hcp and even fcc metals (with the exception of copper and nickel), a change in the fracture mechanisms is observed (the threshold of cold brittleness) which is a characteristic sensitive to structure and composition. The transition to the brittle condition is an attribute of the crystal lattice and is probably due to an increase in the percentage of covalent bonds with decreasing temperatures.

Microstructure and brittleness of structural steels

1. The greater the heterogeneity of the microstructure and the larger the grain size, the greater the susceptibility to brittle fracture. 2. The correlation of susceptibility to brittle fracture of steels with different microstructures is revealed only in tensile tests of notched samples in the brittle condition.

Effect of low-temperature deformation on susceptibility to brittle fracture of steels st. 3ps and 3sp

Effect of low-temperature deformation on susceptibility to brittle fracture of steels st. 3ps and 3sp

Effect of plastic deformation on brittle fracture of steel in the presence of hydrogen

Effect of plastic deformation on brittle fracture of steel in the presence of hydrogen

Effective surface energy of a fracture and the brittle fracture of steel

Effective surface energy of a fracture and the brittle fracture of steel

Hydrogen embrittlement of surface layers of steel during friction in contact with copper alloys

An explanation of brittle fracture of steel during friction in contact with bronze was formulated and the possibility of reproducing and investigating this phenomenon under laboratory conditions was established.

Arctic Engineering For the Petroleum Industry

Abstract THE ARCTIC has been defined in a variety of ways by latitude or tree line, by isotherm or permafrost. For this paper, it will be considered simply as that part of Canada lying north of the 60th parallel. Most of what is discussed here will apply specifically to the sedimentary basin, the prospective oil country bring in the Northwest Territories; other countries, however, also have very prospective arctic areas, and many of their problems will be similar (Figure 1). Long before the current surge of interest in the north, major construction projects had been successfully undertaken in arctic Canada. One of the most outstanding was a railway from Skagway to Whitehorse: built seventy years ago, it is still hauling freight and is an important part of the transportation system supplying the Yukon Territory. In northern Manitoba, the Churchill railway was begun in 1910, through most difficult permafrost conditions. War halted construction for a time, but the line was completed in the late nineteen twenties. Since then we have had various hydropower developments, the construction of major transmission lines and, in the military field, the Early Warning system and the DEW line. The oil industry development along the Mackenzie was started over 50 years ago, and an outstanding achievement during the war years was the construction of some 660 miles of pipeline from Norman Wells to Whitehorse. These represent only a few of the major construction projects on which, over the past several decades, nearly five billion dollars has been spent. The engineering problems discussed here will be those that are unique to the north. They include climate, permafrost, ice and snow, terrain, and remoteness. Although these problems are not new to Canadian engineers, when they have to be faced together they call for new approaches to the engineering development of large-scale oil and gas reserves. To add to the challenge, these developments are going on at a time when everyone is aware of "ecology" and "pollution" as matters of grave public concern. Development of northern Canada will go on, but every effort must be made to establish a proper balance between resource development and environmental protection. This paper will outline our present state of the art and suggest some new approaches to work that will be required. Climate We share our Canadian arctic climate with Russia, Alaska and the Scandinavian countries (Figure 2). In winter it features intense cold, high winds and darkness, in summer long hours of daylight and very little precipitation – so that without the permafrost, the Canadian arctic would be largely a desert. Although we have most of the know-how to be able to design equipment suitable for these conditions, very often what is available has been made for warmer climates and simply moved north for its useful life. We should not be surprised, then, if it performs badly, or fails from such causes as brittle fracture of steel.

Effect of sucrose on hydroerosion of steels

The erosion of carbon and stainless steels under the influence of the impact of a jet of water and aqueous sucrose solutions was studied. It was established that increasing the sucrose concentration (i.e., density) of a solution intensifies the brittle fracture of steels.

A study of the process of cutting with high-speed saws

Phenomena taking place during cutting of metals with high-speed saws were studied. It was established that the main process in the cutting zone is brittle fracture of steels heated to high temperatures (800–1000°C) accompanied by the formation of broken-off chips. A new approach to certain problems of processes of cutting and brittle fracture of hot metals was proposed.

低温用鋼材と脆性破壊

低温用鋼材と脆性破壊

The brittle fracture of steel

The brittle fracture of steel

Studies on the Effect of Residual Welding Stress on Brittle Fracture of Steel, Part IV

Studies on the Effect of Residual Welding Stress on Brittle Fracture of Steel, Part IV

Studies on the Effect of Residual Welding Stress on Brittle Fracture of Steel

The third series of slow notch bend test was performed to investigate the effect of residual welding stress on brittle fracture of steel. Chemical composition and mechanical properties of steels tested are shown in Table 1. Steel YA is more notch-sensitive and YB is more notch-tough than weld metal.For each steel, 2 kinds of unwelded specimens (as rolled and annealed) and 9 kinds of welded specimens (as welded, annealed, 3 pretensioned and 4 low temperature stress relieved) were prepared (Fig. 1). Detailes of welding procedure and low temperature stress relieving conditions are shown in Tables 2 and 3.On each one specimen among welded specimens, residual stress measurement was performed by -resistance wire strain gauges. Fracture test procedure is the same as Van der Veen test. Trs. depo and longitudinal residual stress are shown in Table 5.We can conclude that stress relieving of welded joint increases notch toughness, but plastic strain of weld metal decreases notch toughness, so moderate heat input in low temperature stress relieving is preferable.