Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第17卷    第2期    总第95期    2007年2月

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文章编号:1004-0609(2007)02-0326-05
渗碳时间对梯度硬质合金显微组织和
抗弯强度的影响
龙郑易1, 2, 刘 咏1, 2, 贺跃辉1, 肖逸锋1, 周永贵2, 李 芳2

(1. 中南大学 粉末冶金国家重点实验室,长沙 410083;
2. 自贡硬质合金有限责任公司,自贡 643011
)

摘 要: 采用预烧结-后续渗碳的方法制备钴相呈梯度分布的硬质合金,通过对试样显微组织的观察和抗弯强度的测试,研究渗碳时间对梯度硬质合金显微组织和抗弯强度的影响。结果表明:试样富钴层钴相含量随渗碳时间的延长而增加,试样的抗弯强度随渗碳时间出现了峰值现象,即当渗碳时间少于140 min时,试样的抗弯强度随渗碳时间的增加而增加,在渗碳处理140 min时出现最大值,当渗碳160 min后,试样的抗弯强度开始下降。分析认为,富钴层中金属钴的良好塑性变形能力能有效地吸收来自外部裂纹扩展的能量,提高合金的抗弯强度,同时当渗碳时间过长时(超过140 min)WCη相晶粒出现了聚集长大,造成钴相分布不均匀,并局部形成Co池,导致试样抗弯强度的下降。对于直径为10 mm的矿用梯度球齿,其合理的渗碳时间应控制在120~140 min

 

关键字: 硬质合金;梯度结构;渗碳;显微组织;抗弯强度

Effects of carburizing time on microstructure
and transverse rupture strength of
graded cemented carbides
LONG Zheng-yi1, 2, LIU Yong1, 2, HE Yue-hui1, XIAO Yi-feng1, ZHOU Yong-gui2, LI Fang2

1. State Key Laboratory for Powder Metallurgy, Central South University,
Changsha 410083,China;
2. Zigong Cemented Carbide Co. Ltd., Zigong 643011, China

Abstract:Effects of carburizing time on microstructure and transverse rupture strength of cemented carbide with gradient cobalt structure fabricated by pre-sintering-carburizing process were studied by optical microscopy and transverse rupture strength test. The results show that the cobalt content in the Co-rich layer increases with prolonging carburizing time, the transverse rupture strength of samples increases when carburizing time is less than 140 min and the maximum appears at 140 min. The transverse rupture strength increases efficiently because of the tough Co-rich layer in samples. The distinct decreasing of the transverse rupture strength carburized for more than 140 min is ascribed to the grain growth of WC and η phase. The reasonable carburizing time should be controlled in 120−140 min for the d 10 mm samples.

 

Key words: cemented carbide; gradient structure; carburizing; microstructure; transverse rupture strength

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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