孕育处理和保温时间对高镍铬组织和性能影响  

Effect of inoculation treatment and holding time on microstructure and mechanism of high nickel-chromium cast iron

作　　者：杨宏略 肖志霞 冯建航 陈佳崎 陈兴富 刘杰兵 石立勇 YANG Honglue;XIAO Zhixia;FENG Jianhang;CHEN Jiaqi;CHEN Xingfu;LIU Jiebing;SHI Liyong(College of Materials Science and Engineering,Hebei University of Technology,Tianjin 300131,China;Xingtai Delong Mechanical Roll Co.,Ltd.,Xingtai 054035,Hebei,China)

机构地区：[1]河北工业大学材料科学与工程学院,天津300131 [2]邢台德龙机械轧辊有限公司,河北邢台054035

出　　处：《钢铁》2024年第1期139-147,共9页Iron and Steel

摘　　要：高镍铬铸铁组织中石墨和共晶碳化物的合理匹配,可使高镍铬轧离心复合轧辊具有优异的强度和硬度以及良好的抗热冲击和热裂性。然而当孕育不合理时,碳化物和石墨不仅不会得到有效改善,甚至会形成夹杂物恶化材料性能;同时,在轧辊生产过程中,因铁水冶炼工艺和浇铸工艺的不稳定,导致冶炼后期铁水在中间包中保温时间存在不确定性。基于此,研究了高镍铬铸铁在熔炼后期分别保温3、5和7h,以及浇注前分别添加质量分数为0.4%、0.8%、1.2%的硅铁孕育剂后,铸态组织中的碳化物和石墨变化机制,比较了不同保温时间和孕育处理对铸铁材料硬度的影响规律。结果表明,随着保温时间的延长,高镍铬铸铁组织中的石墨平均尺寸与体积分数增加,但数量密度减少,共晶碳化物出现明显细化且含量减少;保温3h的样品经孕育处理后,能够有效促进石墨形核,但延长保温时间后即使提高孕育剂加入量,石墨平均尺寸和数量密度也无明显改善;保温低于5h时,孕育处理可使共晶碳化物含量减少,但延长保温时间后孕育处理使共晶碳化物含量增加。随着保温时间延长,高镍铬铸铁的硬度逐渐降低;当保温时间大于5h时,经孕育处理的样品的硬度能提高16HRC。研究表明,在高镍铬铸铁熔炼过程中,保温时间应控制在3h内,保温过长会导致石墨过度长大并降低石墨数量,此时仍可通过添加质量分数为0.4%~1.2%的孕育剂来增加石墨数量,但保温超过5h后即使添加孕育剂也无法有效提高石墨数量。High nickel-chromium centrifugal composite rolls have excellent strength and hardness as well as great resistance to thermal shock and thermal cracking,which is attribute to the good match of graphite and eutectic carbides in the structure of high nickel-chromium cast iron.However,the unsuitable inoculation would not effectively improve the structure and even form inclusions to deteriorate the material properties.Meanwhile,in the process of roll manufacturing,holding time of high-temperature iron liquid in the intermediate ladle is uncertain,due to the instability of iron smelting process and casting process.Eutectic carbide and graphite in the as-cast structure of high nickelchromium cast iron was studied after holding for 3h,5hand 7h,and followed by adding 0.4%,0.8%and 1.2%inoculant before pouring.The influence of holding time and inoculant treatment on hardness was also compared.The results show that with the increase of holding time,the average size and volume fraction of graphite increases,but the number density decreases,and the content of eutectic carbides decreases obviously.After inoculation treatment with holding time of 3h,the nucleation of graphite could be effectively promoted,but the average size and number density of graphite did not improve significantly even if the amount of inoculant was increased after increasing holding time.When the holding time is less than 5h,the content of eutectic carbide can be reduced by inoculation treatment,but the content of eutectic carbide can be increased by inoculation treatment after increasing the holding time.The hardness of high nickel-chromium cast iron decreases gradually with the increasement of holding time.When the holding time is more than 5h,the hardness of incubated samples can increase 16HRC.In the smelting process of high nickelchromium cast iron,the holding time should be controlled within 3h,too long holding time will lead to excessive growth of graphite and reduce the amount of graphite.At this time,the amount of graphite can be increased by addi

关 键 词：高镍铬铸铁 孕育处理 保温时间 石墨 共晶碳化物 

分 类 号：TG143.7[一般工业技术—材料科学与工程]