钒加入量对稀土低铬铸铁组织和性能的影响

Effect of Vanadium Addition on Microstructure and Mechanical Properties of RE Low Chromium Cast Iron

采用测试硬度、冲击韧度和观察显微组织等方法,研究了钒加入量对稀土低铬合金铸铁组织和性能的影响。研究表明:在铸态条件下,随着钒含量的增加硬度增大,当钒含量到达1%时,其硬度达到53.6 HRC;经过250℃回火保温2 h的热处理后,试样的硬度呈先增加后降低的趋势,钒含量为0.75%时,硬度达到55.5 HRC。铸态条件下,当钒含量为0.75%时,冲击韧度达到5.8 J/cm2。经过同样的热处理工艺后,试样的冲击韧度有较大程度地提高,当钒含量为0.75%时达到10.7 J/cm2。通过对试样的金相组织观察发现,随着钒含量的增加,网状碳化物数量减少,热处理后局部出现断网,有白色碳化物析出。

The influence of vanadium addition on the microstructure and mechanical properties of RE low chromium alloy cast iron was investigated by means of hardness testing, impact toughness and microstructure observation. The experimental results indicate that, in as-cast condition, the hardness increases with the increase of vanadium content, as the vanadium content reaches 1%, the hardness is about 53.6 HRC. After tempered at 250℃ for 2 h, the hardness of the sample first increase s and then decreases, the hardness becomes 55.5 HRC as vanadium content is 0.75%. Moreover, the impact toughness of as-cast sample reaches 5.8 J/cm^2 as the vanadium content is 0.75%. After above mentioned heat-treatment, the impact toughness is greatly improved, is up to 10.7 J/cm^2 in as-cast with the vanadium content of 0.75%. In addition, the quantity of network carbide reduces with the increase of the vanadium content, and offline network appears in local region after heat-treatment, even some white carbide precipitates.