摘要
通过轴向拉压疲劳试验得到HRB500钢筋在应力比R=0.1时107周次的疲劳强度σ0.1=587.5 MPa,远高于一般碳素结构钢的疲劳强度;再利用三参数幂函数法非线性回归得到S-N曲线方程为lg(Nf)=7.092-1.144 7lg(σmax-586.3);并研究发现直径大小对钢筋的疲劳强度基本没影响,疲劳强度主要与材料的成分、组织及夹杂物有关。还利用扫描电镜与能谱仪分析试样的疲劳断口,得到HRB500钢筋的疲劳破坏均属于表面基体起裂,与钢中脆性夹杂物有关;疲劳裂纹呈放射状在基体中扩展,呈现比较明显的片层状结构,以准解理裂纹扩展为主;瞬断区呈韧性断裂,出现大量韧窝状组织,主要由于夹杂物引起微孔聚集断裂。
By the means of tension fatigue test at stress ratio R = 0.1, it was found that the fatigue strength of HRB500 high-strength rebar for 107 cycles was 587.5 MPa, which was much higher than that of the common carbon structural steel. The curve function log（Nf） = 7. 092 - 1. 144 71g（δmax- 586. 3 ） was also obtained by nonlinear regression with the method of three parameters power function. The study also found that the diameter size of rebar hardly impacted fatigue strength. Fatigue strength was mainly related to material composition, microstructure and inclusion. Furthermore, the fatigue fracture surfaces of the specimen were analyzed by using SEM and EDS. HRB500 rebars were all damaged by crack initiation from surface substrate which was associated with brittle inclusions in steel; Fatigue crack radially extended in the matrix and revealed the obvious layered structure, which was mainly based on quasi-cleavage; Transient breaking area exhibited ductile fracture mechanism and appeared a large number of dimples, mainly due to many inclusions contained in steel, which caused microporous gathered fracture.
出处
《机械强度》
CAS
CSCD
北大核心
2015年第2期248-253,共6页
Journal of Mechanical Strength
