摘要
液析碳化物是轴承钢中最有害的碳化物,可通过扩散退火将其消除或减少。为了消除液析碳化物并改善碳化物的均匀性,对GCr15轴承钢连铸坯进行了分别加热至1200、1230、1250和1280℃保温0.5、1和3 h空冷的扩散退火。对铸坯不同部位以及由铸坯轧制的粗轧坯和线材进行了金相检验和能谱分析。结果表明:液析碳化物集中在连铸坯中心,80%的液析碳化物尺寸为20~80μm,为(Fe,Cr)_(3)C和少量(Fe,Cr)_(7)C_(3);线材中带状和网状碳化物主要源于液析碳化物;扩散退火温度越高、时间越长,能溶解的碳化物尺寸越大;随着退火时间的增加,碳化物溶解速率下降;GCr15等高碳铬轴承钢合适的扩散退火工艺为1250℃保温3 h空冷。
Carbides precipitated from molten steel in bearing steel are the most harmful,and can be eliminated or decreased by diffusion annealing.To eliminate carbides precipitated from molten steel and to improve homogeneity of carbides,the continuous casting slab of GCr15 steel was diffusion annealed by heating at 1200,1230,1250,and 1280℃for 0.5,1,and 3 h followed by air cooling,respectively.The different positions in the cast slab,rough-rolled billet and wire rod made from the cast slab were subjected to metallographic examination and energy spectrum analysis.The results indicated that(a)the carbides precipitated from molten steel concentrated in center of the continuous casting slab,80%of carbides precipitated from molten steel was as large size as 20 to 80μm,and they were(Fe,Cr)_(3)C and small amount of(Fe,Cr)_(7)C_(3);(b)the banded and net carbides in the wire rod were derived predominantly from the carbides precipitated from molten steel;(c)the higher the diffusion annealing temperature and the longer the holding time,the larger the size of dissoluble carbides was;(d)as the annealing time increased,the dissolution rate of carbides decreased;and(e)the diffusion annealing practice applicable to high carbon chromium bearing steel such as GCr15 steel is heating at 1250℃ for 3 h then air cooling.
作者
尹啸
雷书伟
徐曦
李慧改
YIN Xiao;LEI Shuwei;XU Xi;LI Huigai(School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;Iron and Steel Research Institute of Angang Group,Anshan Liaoning 114009,China)
出处
《上海金属》
CAS
2022年第6期78-85,91,共9页
Shanghai Metals
关键词
高碳铬轴承钢
碳化物
均匀性
扩散退火
high carbon chromium bearing steel
carbide
homogeneity
diffusion annealing
