Hollow Member And Hollow Member Manufacturing Method

Abstract: According to the present invention, a hollow member has a circumferential hardness difference section in at least a portion in the longitudinal direction along the center axis thereof. When viewing the circumferential hardness difference section in a cross-section perpendicular to the center axis, a thickness difference, derived by subtracting the minimum value of the thickness in the circumferential direction of the cross-section from the maximum value of the thickness, is no more than 20% of an average value of the thickness over the entire circumference of the cross-section. Furthermore, when the average of the integral of the Vicker’s hardness over the entire circumference of the cross-section is used as a hardness threshold, the cross-section includes: a low-strength range in which the Vicker’s hardness in the circumferential direction is no more than the hardness threshold; and a high-strength range in which the Vicker’s hardness in the circumferential direction exceeds the hardness threshold.

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