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140min时,试样的抗弯强度随渗碳时间的增加而增加,在渗碳处理140min时出现最大值,当渗碳160min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140min),WC与η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10mm的矿用梯度球齿,其合理的渗碳时间应控制在120～140min。
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 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.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2007年第2期326-330,共5页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(50323008)
关键词
硬质合金
梯度结构
渗碳
显微组织
抗弯强度
cemented carbide
gradient structure
carburizing
microstructure
transverse rupture strength
