What Material Should Be Used for Coal-Fired Chain Grate Bars?
- Medium-Silicon Heat-Resistant Nodular Cast Iron RQTSi5 (High-Silicon Nodular Iron) The most commonly used primary material, resistant to high temperature, oxidation, thermal fatigue, and wear. Suitable for conventional coal-fired chain grate furnaces, capable of withstanding high furnace temperatures over the long term, balancing cost and service life. Ideal for the vast majority of small and medium-sized coal-fired chain grate boilers.
Also available are chromium-series heat-resistant cast iron (RTCr, RTCr2, RTCr16, and other alloy heat-resistant cast iron), which offer superior high-temperature resistance and sulfur corrosion resistance, suitable for high-temperature and high-sulfur coal operating conditions, but at a higher cost with toughness considerations.
Ordinary gray cast iron (HT200/HT250) is only suitable for low-temperature, light-load, low-parameter older boilers, with a shorter service life, and is not suitable for long-term high-temperature primary operating conditions.
Malleable cast iron (KTH series): used for some active grate bars, offering good toughness and impact resistance, suitable for active bar sections subject to high stress, but not suitable for areas subject to prolonged direct high-temperature exposure.
- High-End Operating Conditions: Heat-Resistant Cast Steel / Heat-Resistant Alloy Steel Such as high-chromium cast steel, ZG40Cr9Si2, etc., used for high-temperature, high-calorific-value coal, and heavy-duty large boilers, offering excellent high-temperature creep resistance and wear/corrosion resistance, but at a significantly higher price.
Selection Recommendations Conventional industrial coal-fired chain grate furnaces: prioritize RQTSi5 medium-silicon heat-resistant nodular cast iron grate bars, balancing heat resistance, wear resistance, and cost; High-sulfur, high furnace temperature conditions: select chromium-alloy heat-resistant cast iron (such as the RTCr series); Active load-bearing grate bars: can be paired with malleable cast iron / KTH series material to improve toughness; Old boiler, light-load conditions: HT250 and other high-quality gray cast iron can be used short-term, but with a shorter service life, not recommended as a first choice.
One-Sentence Summary: For conventional coal-fired chain grate furnaces, RQTSi5 medium-silicon heat-resistant nodular cast iron grate bars are the preferred choice.
