【摘要】 对热轧H型钢的高应变低周疲劳性能进行了研究。采用轴向应变控制的方法,在Instron-1342型电液伺服疲劳试验机上测定了热轧H型钢的低周疲劳性能数据,研究了在循环载荷下材料的循环应力响应特征、循环应力与应变关系,并用Coffin-Manson公式拟合得到热轧H型钢的疲劳寿命计算公式,据此计算了Nf=100时的aσ.Δtε值。通过断口扫描发现,裂纹不仅在试样表面处形核,同时也在试样内部杂质处形核,然后通过不断的扩展形成微裂纹,许多微裂纹通过扩展连接形成宏观裂纹,最终导致材料断裂。更多还原

【Abstract】 High strain low cycle fatigue properties of the hot rolled H beam steel were investigated.By using an axial strain control method,the low cycle fatigue properties were tested on a type Instron 1342 fatigue test machine.Cycle strain response character of the tow kinds of hot rolled H beam steel and the relationship between cycle stress and strain were researched.Conffin-Manson formula was used to derive fatigue life formula of the materials,and the values of σa·Δεt were obtained when Nf=100.The SEM micrographs revealed that the microcracks nucleation occurred not only at the surface but also in the interior of the specimen.Due to the propagation of the microcracks,they were joined together and the macrocracks were formed,at last,when the stress was higher than the ultimate strength of the material,the material was broken.更多还原