| 摘要 |
Apart from iron the steel contains from 0.25 to 0.45 percent by weight of carbon, from 0.20 to 0.80 percent by weight of manganese, from 0.10 to 0.60 percent by weight of silicon, from 1 to 2 percent by weight of chromium, from 4 to 5 percent by weight of nickel, from 0.20 to 0.60 percent by weight of molybdenum, from 0.20 to 0.60 percent by weight of wolfram, from 0.08 to 0.20 percent by weight of niobium, up to 0.030 percent by weight of sulphur, up to 0.030 percent by weight of phosphorus. The rest is iron. The mutual ratio of alloying agents hardens by means of carbidic phase of various sizes the spaces between grains and the interfaces. This results in creation of basic metal matrix, which is characteristic by its high resistance against creeping in standard temperatures. This physical quality, important mainly in calibration of measuring systems, is decisive for accuracy and reliability of the devices.
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