Abstract: The test interstitial-free steel IF(/% : 0.0036-0.0049C, 0.005-0.007Si, 0.11-0.12Mn, 0.007P, 0.005S, 0.007-0.011Alt, 0.047-0.051Ti, 0.0030N, 0-0.0037Ce) is melted by a 10 kg vacuum induction furnace, and forged to 30 mm x 25 mm billet, finishing forging at 950 ℃ , air cooling. With using Gleeble-1500D thermal simulation testing machine the tensile test on the testing steel with strain rate 0. 1 s^-1 at 750-1150 ℃ has been carried out to study the effect of micro rare earth (RE) element Ce on high temperature tensile properties of the IF steel. As compared with IF steel non-containing Ce, the hot plasticity ( reduction of area-Z value) and hot tensile strength ( Rm value) of IF-Ce steel containing 0. 0037%Ce increase obviously, but with increasing temperature the increment decreases ； the reduction of area and tensile strength at elevated temperature of IF steel and IF-Ce steel respectively are 77.62% -110 MPa for IF and 88.65%-160 MPa for IF-Ce at 750 °C ； 87.35% -85 MPa for IF and 92.88% -100 MPa for IF-Ce at 950 ℃: and 85.68% - 55 MPa for IF and 90.62% -58 MPa for IF-Ce at 1150 °C. The main reasons to increase hot plasticity and hot tensile strength of IF steel by adding RE element are that the element Ce improves structure of steel, fines grain size, and segregates and clusters at grain boundary to increase the strength of grain boundary.

Key words: RE Element Ce, IF Steel, High Temperature Mechanical Properties, Structure

摘要： 试验用无间隙原子钢-IF(/%:0.0036~0.0049C，0.005~0.007Si，0.11~0.12Mn，0.007P，0.005S，0.007~0.011Alt，0.047~0.051Ti，0.0030N，0~0.0037Ce)由10 kg真空感应炉熔炼,锻成30 mm×25 mm方坯,终锻950℃,空冷。通过Gleeble-1500D热模拟试验机对试验钢在750~1150℃进行应变速率0.1 s^-1的拉伸试验,研究微量稀土Ce对该IF钢高温拉伸性能的影响。与不含Ce的IF钢相比,含0.0037%Ce的IF钢的热塑性(Z值)和热强性(Rm值)有明显提高,但随温度提高,增加值减少;IF钢和IF-Ce钢的高温断面收缩率、抗拉强度分别为750℃:(IF)77.62%-110 MPa和(IF-Ce)88.65%-160 MPa;950℃:(IF)87.35%-85 MPa和(IF-Ce)92.88%-100MPa；1150℃:(IF)85.68%-55 MPa和(IF-Ce)90.62%-58 MPa。稀土元素改善钢的组织、细化晶粒、偏聚于晶界提高晶界强度是其提高IF钢热塑性和热强性的主要原因。

关键词: 稀土元素Ce, IF钢, 高温力学性能, 组织