碳镍含量对耐铝液腐蚀低合金灰铸铁组织和性能的影响

Effect of Carbon and Nickel Content on Microstructure and Properties of Low Alloy Gray Cast Iron

热电偶保护套管是保证热电偶在高温熔体中正常工作的关键部件。在目前实际应用的热电偶保护套管低合金灰铸铁成分基础上,设计了少碳组、含镍组来研究碳和镍对低合金灰铸铁组织、力学性能及耐铝液腐蚀性的影响。结果表明:低合金灰铸铁在减少碳含量后,珠光体、碳化物数量增加,石墨、铁素体和共晶团含量减少,力学性能提高,耐铝液腐蚀性降低;添加镍后,珠光体、共晶团及石墨组织含量增加,碳化物数量变化不大,力学性能变化不明显,而耐铝液腐蚀性提高;在铝液对低合金灰铸铁的腐蚀过程中,基体和铝液间形成由FeAl_3相和Fe_2Al_5相组成的合金层。

The thermocouple protective sleeve is a vital component during the thermocouple immersing in hot temperature melt. In the present work the possibility of improving the corrosion resistance of low alloy gray cast iron to molten aluminum was explored through reducing carbon content or adding a small amount of nickel in the gray iron, and the microstructure, mechanical properties and corrosion resistance of the low alloy gray cast irons used as thermocouple protective sleeve were studied. The results showed that when carbon content in grey iron was reduced, the number of carbides and pearlite content increased, graphite and eutectic cells count as well as ferrite content decreased, and the mechanical properties and the corrosion resistance to molten aluminum were improved;when a small amount of nickel was added in gray iron, pearlite content with eutectic cells and graphite count increased, but the number of carbides and mechanical properties had not obvious change,, the corrosion resistance to molten aluminum was improved. A alloy layer mainly consisting of Fe2Al5 and FeAl3 was formed between the substrate and aluminum liquid in the corrosion process of low alloy gray cast iron in molten aluminum.