SHAFT MEMBER

To provide a shaft member capable of suppressing creep deformation and improving a rolling fatigue life under a high-temperature environment where a moment load is applied.SOLUTION: The shaft member is made of steel, and provided with an outer peripheral surface which comes into contact with a rolling element. In a region where a distance from the outer peripheral surface in the radial direction of the shaft member is equal to or smaller than a first distance, hardness is 653 Hv or higher. In a region where the distance from the outer peripheral surface in the radial direction of the shaft member is equal to or larger than a second distance, a retained austenite amount is 7 volume percent or lower. The first distance is larger than that in the radial direction from the outer peripheral surface to a position where maximum shearing stress becomes 650 MPa when the rolling element comes into contact with the outer peripheral surface. The second distance is 1.5 times or less of the distance in the radial direction from the outer peripheral surface to the position where maximum shearing stress becomes 650 MPa when the rolling element comes into contact with the outer peripheral surface.SELECTED DRAWING: Figure 3 【課題】モーメント荷重が加わる高温環境下におけるクリープ変形の抑制及び転動疲労寿命の改善が可能な軸部材を提供する。【解決手段】軸部材は、鋼製であり、転動体に接触する外周面を備える。軸部材の径方向における外周面からの距離が第１距離以下の領域では、硬さが６５３Ｈｖ以上になっている。軸部材の径方向における距離が第２距離以上の領域では、残留オーステナイト量が７体積パーセント以下になっている。第１距離は、外周面から転動体と外周面とが接触した際の最大せん断応力が６５０ＭＰａとなる位置までの径方向における距離よりも大きい。第２距離は、外周面から転動体と外周面とが接触した際の最大せん断応力が６５０ＭＰａとなる位置までの径方向における距離の１．５倍以下である。【選択図】図３