Cast Iron Boiler Fire Grate Bar
Heat-resistant alloy materials include heat-resistant alloy cast steel and heat-resistant alloy cast iron. Heat-resistant alloy cast steel refers to the special steel with high oxidation resistance, namely thermal stability and thermal strength, at high temperature through alloying design.
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Cast Iron Boiler Fire Grate Bar
Heat-resistant alloy materials include heat-resistant alloy cast steel and heat-resistant alloy cast iron. Heat-resistant alloy cast steel refers to the special steel with high oxidation resistance, namely thermal stability and thermal strength, at high temperature through alloying design. Compared with heat-resistant alloy, cast iron has higher carbon content, but the principle of alloying is similar. In order to improve the thermal stability of the alloy, after adding Cr, Si, Al and Ni to the alloying method, dense oxide films such as Cr2O3, SiO2, Al2O3 and strongly with high melting point on the surface of the alloy, or a dense composite oxidation film, so as to improve the thermal stability of the alloy oxide film. Therefore, according to the alloying method, the grate material can be divided into Cr, Si and Al heat resistant materials.
With the development of industry, the high temperature working conditions are getting worse and worse, in order to extend the service life of the equipment, at home and abroad have been committed to the research of heat resistant alloy materials, developed a series of heat resistant cast steel and heat resistant cast iron. Cr heat resistant steel with its excellent thermal strength, creep resistance, good high temperature oxidation resistance and other types of corrosion ability [13,14,15]. Most of the research at home and abroad is applied to petroleum, chemical industry and power station boiler [16,17] and other industries, such as boiler superheater, header and steam pipeline. These heat resistant steels are mainly high chromium heat resistant steel with chromium content of 9%~12%. Typical representatives of this series are 12 CrMoV heat-resistant steel and new high-chromium steel [18,19,20] developed based on it, including P91 / T91 (X10CrMoVNb9 1) from America, E911 from Europe, 91 and P92 / T92 (NF616M), HCM12A (T122) [21], etc.; China developed austenitic high-chromium heat-resistant steel including 102 (12Cr2MoWVTiB), HCM 2 S, T24 (7CrMoVTiB10-10) [22], etc. Within a certain range, with the improvement of chromium and nickel content, its heat resistance will be improved. This kind of Cr heat resistant steel tends to have high Cr and Ni content, such as ZG40Cr25Ni20, ZG35Cr18Ni25Si2 and ZG30Cr20Ni10. Considering its economy, Cr heat resistant steel [23,24] with Mn and N Ni appeared, such as ZG30Cr22Ni4Mn7Si2RE and UNSS20910. Cr series heat-resistant cast iron includes RTCr, RTCr 2, RTCr16 and high Cr cast iron.
Further development saw the emergence of Al series and Si series heat-resistant cast iron with resource-rich Al and Si as the main oxidation elements. Common Al series heat-resistant cast iron are RQTA14Si5, RQTA15Si5 and RQ2TA122 [25]. With the increase of Al content, the heat resistance is improved, and may even exceed Cr alloy. However, it must be pointed out that Al series heat-resistant cast iron is more brittle and the production process is difficult to control. Si series heat-resistant cast iron to RTSi 5 defect shape, the water vapor produced by the coating leads to the pores. This is due to the production process, the workers in the paint drying and inspection link.
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