Study Of The Fire-resistant Mechanism For Fire-resistant Steels

Steel structure is a representative of the modernistic constructure, but which have a fatal restriction of fireproofing. Therefore, there was an increasing demand for eliminating or restricting fire-resistant coating. The fire-resistant steel meets to the needing.Microstructure and alloy elements are the major factors to determine material properties. In order to probe in the relationship between microstructure and alloy elements with the fire-resistant steels'properties, and offer to a reference to the fire-resistant steel development in microstructure and alloy elements design. This paper adopts to industrial trial-produced fire-resistant steels. The mechanical properties and microstructure of the industrial trial-produced fire-resistant steels was investigated. By tempering, the effects of alloyed elements on microstructure were investigated, the dependence of microstructure on fire-resistant steels of properties was discussed.The testing result indicate: YS ration (%) ≥ 2/3(YSration(%)= σ_s(600℃)/σ_s(room-temperature)), YR(%)(σ_s/σ_b) ≤ 0.80. Each of fire-resistant steel's elevated temperature strength accordes with the Building Standards of the fire-resistant steels.The fire-resistant steels for buildings meet increasing steel's elevated-temperature strength while assuring earthquake resistance, weldability and other properties betterthan those of conventional steels for buildings.lt has found that multiphase microstructure consisting of polygomal ferrite, pearlite, grain banite is the basic microstructure of fire-resistant steels. The fine distribution of M-A island is a mostly factor of keeping significant elevated temperature properties and low yield ratio on fire-resistant steels for building. At elevated temperature, the stable microstructure is propitious to evaluate high-temperature properties of fire-resistant steels. At the same time, alloy elements: molybdenum, chromium, niobium and titanium are profitable alloy elements.