研究了带环状预裂纹不锈钢圆棒试样在循环扭转载荷下、门槛值附近的疲劳裂纹扩展行为，用应力强度因子表征了裂纹扩展开始的门槛值。
Near threshold fatigue crack growth tests were conducted under torsion on circumferentially pre-cracked round bars of a stainless steel .
不锈钢圆棒