00Cr18Ni10N奥氏体不锈钢200-600℃高温疲劳性能的研究

200-600℃ Elevated Temperature Fatigue Properties of 00Cr18Ni10N Austenitic Stainless Steel

试验用00Cr18Ni10N钢(/%:0.018C,0.41Si,1.68Mn,18.18Cr,10.38Ni,0.16N)经1tEAF-AOD-ESR冶炼,锻成Φ30mm材和1050℃固溶处理,进行了00Cr18Ni10N钢200-600℃光滑(K_(t)=1)、缺口(K_(t)=3)的轴向高周疲劳性能研究,绘制了疲劳S-N曲线、计算了疲劳极限,并对疲劳试样的典型断口进行了SEM观察。结果表明,光滑试样的疲劳极限随试验温度升高而降低,缺口试样的疲劳极限对试验温度变化不敏感。当应力集中系数由K_(t)=1提高到K_(t)=3时,00Cr18Ni10N钢的200、400、600℃下10^(7)周次条件疲劳极限分别从530、506、410MPa,降低到323、370、392MPa。表明在高温下00Cr18Ni10N钢存在疲劳极限对应力集中敏感,且应力集中敏感性随着试验温度的升高而降低。疲劳试样的断口形貌由疲劳源区、疲劳裂纹扩展区和瞬断区组成,疲劳起源于表面加工刀痕的不连续位置,呈韧性断裂特征。

The tested 00Cr18Ni10N steel(/%:0.018C,0.41Si,1.68Mn,18.18Cr,10.38Ni,0.16N)is melted by 1 t EAFAODESR process,forged toΦ30 mm bar and solid-solution-treated at 1050℃.The axial high-cycle fatigue properties of 00Cr18Ni10N steel with two stress-concentration coefficients(SCs)(smooth:K_(t)=1,notch:K _(t)=3)at 200-600℃are studied.The fatigue S-N curve is obtained,the fatigue limits of two SCs are calculated and the typical fracture morphologies of fatigue specimens are observed by SEM.The results show that fatigue limits of the smooth speci-mens decrease with increasing of test temperature,and the fatigue limits of the notch specimens are not sensitive to the change of test temperature.When SCs rises from K_(t)=1 to K_(t)=3,the 10^(7) cycles fatigue limits of 00Cr18Ni10N steel at 200,400,and 600℃decreases respectively from 530、506、410 MPa to 323、370、392 MPa.It shows that the 00Cr18Ni10N steel has obvious fatigue limit stress concentration sensitivity at elevated temperatures,and the stress concen-tration sensitivity decreases with increasing of test temperature.The fracture of the fatigue specimen is composed of three parts:the fatigue source zone,the fatigue crack propagation zone and the instant fracture zone.The fatigue originates from the discontinuous positions of the surface machined tool marks and exhibits a ductile-fracture characteristic.