Effects of Rare Earths on the Tempering Transformation Kinetics of High Carbon Steel

ＥｆｆｅｃｔｓｏｆＲａｒｅＥａｒｔｈｓｏｎｔｈｅＴｅｍｐｅｒｉｎｇＴｒａｎｓｆｏｒｍａｔｉｏｎＫｉｎｅｔｉｃｓｏｆＨｉｇｈＣａｒｂｏｎＳｔｅｅｌＬｉｎＱｉｎ（林勤）；ＦｕＴｉｎｇ－Ｌｉｎｇ（付廷灵）；ＤｕＹｕａｎ－Ｓｈｅｎｇ（杜垣胜）ＹｕＺｏｎｇ－Ｓ...     

Mechanism and Influence Factors of V_6O_(13) Synthesis

The mechanism and influence factors of thermal decomposition of NH_4VO_3 in Ar to produce V_6O_(13)were investigated by TG-DTG, DSC, X-ray diffraction and orthogonal design experiments at 25～450℃.Theprocess includes four reactions, among which the reduction of V_2O_5 by NH_3 is one of the most importantstagrt controlling the constituents of the fina1 products, and it is affected by heating rate and amount ofNH_4VO_3 singnificantly. This reduction reaction is controlled by a first order reaction or nucleation and nucleigrowth with a kinetic equation--ln(l-a)=kt,and apparent activation energy of 410kJ/molis obtained.     

Behaviour of Rare Earths in Solid Solution in Steel

The contents of rare earth metals(REM) insolid solution in 16 Mn steel were determined bymeans of inductive coupling plasma (ICP)spectroscopy.The amount of REM in solid solutionis only a few ppm in the steel with MnS inclusions,which rises slightly with the increasing of REMcontent in steel.At RE/S>1.9,the MnS inclu-sions in steel disappear completely,the REM con-tent in solid solution increases rapidly with the in-creasing of REM content.The solubility of ceriumin 16 Mn steel(st 52)is less than 0.011 wt—％ atroom temperature.The results obtained indicate that REM in sol-id solution reduce the amount of pearlite and in-crease that of ferrite and its microhardness.Dis-solved REM oculd increase temperature of criticalpoints,alleviate band structnre and suppressgrowth of austenite grains.     

中注管加入稀土与耐火材料的作用

中心注管钢流中加稀土的试验生产表明，钢中稀土可腐蚀中注管和汤道的粘土质耐火材料，并随稀土加入量和加入时间的增加而加，剧腐蚀产物中ＳｉＯ２、Ａｌ２Ｏ３逐渐减少或消失，ＲＥＡｌＯ３，ＲＥ－Ａｌ－Ｓｉ－Ｏ，ＲＥ２ＳｉＯ２等复合氧化物相依次出现，腐蚀层逐渐增厚。稀土与耐火材料反应对钢中夹杂物有一定影响，中注管部位出现大型外来ＲＥ－Ａｌ－Ｓｉ－Ｏ复合夹杂，但能被汤道耐火材料及保护渣吸收，本稀土处理工艺可使钢