Preventing steel deterioration on the stage of construction design

While designing steel constructions it is vital to keep the possible deterioration in mind, which can take place as a result of the adverse influence of various factors. Naturally, during the design process, certain stages should be covered and carefully investigated in order to reach best quality and most importantly safety of workers and after occupants of the building.

To prevent deterioration of construction several steps should be considered during the period of design-

Figure 2. Classification by commercial name and structure of ferrous alloys (3)

ing. Figure 2 illustrates classification of ferrous alloys by commercial name and structure. To start with, suitable steel must be chosen according to construction.

Purpose, size and dynamic loads in the future building influence the choice of steel. For residential buildings with normal load usual carbon steel with standard strength. However, for elements with unusual load, for example columns, could be used low-alloy steel. The way of smelting must be considered as well. After that, chemical compounds of steel, production methods and way of heat treatment influence change of properties under low temperatures. Additive of nickel and manganese contribute elevation of resilience. Moreover, similar effect can provide adding of aluminum and vanadium. (3)

Carbon steel

According to The American Iron and Steel Institute (AISI) steel is reckoned to be carbon steel when no minimum capacity is specified or required for chromium, cobalt, columbium [niobium], molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other element to be mixed to receive a needed alloying effect; when the specific minimum for copper does not outgo 0.40 per cent; or when the maximum content determined for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60. (4)

Carbon steel experience various deoxidation approaches which can be used for classification: capped, killed, semi-killed or rimmed steel. Choice of deoxidation approach directly influence assets of production steel. But, of course, not only the way of manufacturing but also and mainly consistency of carbon determine mechanical properties in the way that with rise of carbon in alloy rise strength and hardness. In other words, amount of included carbon regulates preference in choice of type of steel for construction. Indeed, basically under 2% of carbon in steel constitute one of four types: high-carbon, ultrahigh-carbon, low-carbon or medium-carbon steels. (3)

Low-alloy steel

Purpose of low-alloy steel or microalloyed steel is to show high unsusceptibility to corrosion and at the same time ability to undergo heightened mechanical loads. Henceforth, less variations left for chemical consistency of material. Usually chemical compound of low-alloy steel represented by 0.05% to 0.25% of carbon which guarantee needed flexibility and welding properties, up to 2.0 % of manganese, minor quantity of chromium, copper, nickel, niobium, nitrogen, molybdenum, titanium, vanadium and zirconium in diverse variations. (4)

Date: 2015-12-18; view: 745