410· 北京科技大学学报 2004年第4期 Eloctrostatic and Lubricant Performances of Compound Lubricants in P/M Elec- trostatic Die Wall Lubrication YANG Xia,CHEN Bangfeng,GUO Shiju Institute of Powder Metallurgy,University of Science and Technology Beijing.Beijing 100083,China ABSTRACT The electrostatic and lubricant performances of compound lubricants-50%EBS wax+50%graph- ite and 50%EBS wax+50%BN in P/M electrostatic die wall lubrication were investigated.The results show that the addition of BN can improve the charging performance of EBS wax,while graphite makes it worse.The combi- nation of 50%EBS wax and 50%graphite exhibits excellent lubricant performance,resulting in a fairly high green density,but the mixture of 50%EBS wax and 50%BN has less beneficial effect.When the mold temperature is 150C,which is above the melting point of EBS wax,the lubricant performance of the 50%EBS wax+50%graphite becomes worse,while the 50%EBS wax+50%BN is little influenced. KEY WORDS powder metallurgy;electrostatic;lubrication;lubricants 6望esPeoTe5重a6t6望c6望望里%Ye6坐6望a6Ye6堂e6Yc6堂e55空a6Y6望a5堂a6亚c5变s里a6s￥6t6望5堂%望m望s2s6s堂e626o里cs里as里as里6Y6Y6Ys里6望a From Journal of University of Science and Technology Beijing,2004,11(4):338 Thermo-stability of ultra-fine non-equilibrium microstructures WU Huibin,YANG Shanwu,GUO Aimin,YUAN Shaoqiang,SHANG Chengjia,HE Xinlai Materials Science and Engineering School,University of Science and Technology Beijing,Beijing 100083,China ABSTRACT The evolution of the microstructures and hardness of a bainitic plate steel during tempering at 650 C has been investigated.The steel was manufactured by RPC(relaxation-precipitation controlling phase transforma- tion)technique.A part of the plate was reheated to 930C and held for 1 h before quenched into water(RQ).No ob- vious change was detected by means of optical micros-copy in the RPC steel tempering for 0.5 h,while dislocation cells were formed inside the bainite laths,accompanied by an obvious drop of hardness.The bainite laths started to coalesce in some regions,but the sample hardness kept nearly constant during temper-ing from I to 7 h.With further tempering,polygonal ferrite was formed in local regions while the hardness decreased dramatically.The RQ sam- ples softened faster during tempering and finally transformed into the polygonal ferrite completely.These results indi-cate that the thermo-stability of fine non-equilibrium microstructures is tightly related to their history. KEY WORDS microalloyed steel;bainite and martensite;tempering;RPC technique一 北 京 科 技 大 学 学 报 年 第 期 仃 ， 月石 ’ ， 妈 飞卿 ， 明 不韶 乐 ， 】 一 ， 『即 召 七 ， 『即 ， 笋 ， 从币 ， ， ， 歹即 ， 、 四罗 公吐 仰 口 哪到 ， 口， 刃 一 一 一 仃 牙 初 ， 别刃 ， ， 更月 ， 尸嚼， ， ， 吨 ， 址 即 吨户 加川 山 叭 一 即 ， 山 ， 画 勿 而 五 ， 别叭 杨 颐 份 西 九吐 帅阴 ， 力 】 歇 刀 币 一 一 一 ” 犷 叮