Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników
Powiadomienia systemowe
  • Sesja wygasła!
  • Sesja wygasła!

Znaleziono wyników: 9

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
EN
Structures of carburized layers after the surface saturation process in gaseous, liquid or solid medium and after subsequent heat treatment (hardening and low-temperature tempering) consist mainly of high carbon plate martensite with a certain portion of retained austenite. The presence of retained austenite (RA) in carburized layers is mostly considered as undesirable because it decreases hardness of the hardened layer and furthermore, a spontaneous conversion to a ferritic-carbide mixture of a bainitic type, accompanied by a change of properties, dimensional instability and the local increase in internal stress with the possible formation of cracks, can occur. The proportion of retained austenite is, therefore, a significant characteristics of the quality of hardened layers. This work deals with the evaluation of the volume fraction of retained austenite in carburized layers using image analysis on metallographic images.
EN
The work is focused on evaluation of resistance of the welded joint made of supermartensitic 13Cr6Ni2.5Mo stainless steel to sulfide stress cracking. Testing method A and solution B in accordance with NACE TM 0177 were used. All the testing samples were ruptured in a very short time interval but welded joint samples were fractured primarily in the weld metal or in heat affected zone and not in the basic material. Material analysis of samples were made with use of a ZEISS NEOPHOT 32 light microscope and a JEOL 6490LV scanning electron microscope.
EN
Personal computers including all its parts, CPU, monitor, keyboard and mouse belong to the group of "information technology and telecommunication equipment". At the present consumption rate personal computers are scrapped when they are fully or partly operating, but they do not satisfy their owners in their parameters. Operating parts, such as hard disks from personal computers, can be further used, e. g. as backup sources or by less demanding users. If it does not happen, electric and electronic waste is produced. According to the Waste Disposal Association it is necessary to support the use of waste in order to eliminate the amount of wastes determined for disposal and to preserve natural resources, particularly by reuse, recycling, composting and use of energy from wastes. Selected parts of waste hard disks from personal computers were evaluated metallographically. In addition, the used coatings were characterized and their thickness was determined. As it was found out, basic parts of hard disks are produced from basic metals, such as iron, aluminium and copper. The contents of the contribution should add to increasing knowledge and the possibilities of electrical waste recycling.
EN
Mobile telephones belong to the fastest updated electronic devices, which generates thousands of tons of waste every year. According to the research by the Nokia company, only very few mobile telephones are recycled after their expiration date, whereas 80 % of Nokia devices are recyclable and contain valuable sorts of material. It is exactly this type of electronic waste that can provide us with various usable material sorts including metals such as copper, iron, nickel, silver and gold. A mobile telephone contains approx. 15-18 % of copper and 3 - 8 % of iron. A significant part of a mobile telephone is composed from miscellaneous types of plastics which are easy to recycle after sorting. Out-of-use mobile telephones belong to the waste group of electrical and electronic devices. Therefore, with respect to the environment, it is necessary to pay an intensive attention to the issue of collecting and recycling this type of devices, since any mobile phone which is not used any more constitutes an environmental burden or the resource of valuable raw materials. This thesis includes a material analysis of selected mobile telephones.
9
Content available remote Sulphide Stress Cracking of API Carbon Steels
EN
In this paper results of SSC resistance of the same carbon steels are summarized. Several grades of steels have been tested, conforming to API grades X52 and X70 (API 5L Specification). Steels were tested in an as-received state or after laboratory heat treatments including quenching and termpering. Results showed that the resistance of steels to SSC depends strongly on their microstructure. Heats containing bands of non-tempered martensite or bainite exhibited rather poor resistance to SSC and failed and stresses well below the yield strength when tested according to the NACE TM 0177, Method A. It must be pointed out that hardness of all studied steels was well bellow the limit of 22 HRC. Tempering or quenching had a beneficial effect on resistance of steels to SSC despite the fact that mechanical properties (and hardness) increased. All the results indicate that microstructure plays important role also in the case of SSC. If this fact is not respected, a material non resistant to SSC can be chosen.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.