A round bar of 25 mm diameter is machined from AISI 4130 quenched and tempered to a hardness of 258 HB. From Table A-23, the tensile strength of the bar material can be obtained as Sut The surface factor ka = 0.9 If the bar is subjected to a bending load, the size factor k = 0.80 For a bending load, kc = 1.0 The endurance limit S = 304.2 MPa = 895 MPa