Turning insert for metal cutting

A turning insert for longitudinal external turning of hardened steel, comprising:

• a top surface, an opposite bottom surface, a first side surface, an opposite second side surface, a front surface, and an opposite rear surface, wherein the top and bottom surfaces are connected by the first side surface, the second side surface, the front surface, and the rear surface;
• a longitudinal axis intersecting the front and rear surfaces, the longitudinal axis extending mid-way between the first and second side surfaces;
• a cutting edge comprising cubic boron nitride, the cutting edge being at least partly formed at an intersection between the top surface and the front surface, the cutting edge including a forward point intersecting the longitudinal axis in a top view, a tangent line of the cutting edge at the forward point extending in a top view perpendicular to the longitudinal axis, the turning insert being symmetrical or substantially symmetrical in a top view in relation to the longitudinal axis;
• and
• a head portion connected to a stem portion, wherein a greatest width of the head portion is greater than a greatest width of the stem portion, where said widths are measured perpendicular to the longitudinal axis, the head portion including the cutting edge and a land portion adjacent to the cutting edge, the cutting edge having a surface generating cutting edge including the forward point, wherein in a top view the surface generating cutting edge is convexly curved at a radius of curvature greater than 60 mm and less than 200 mm, and wherein a length of the surface generating cutting edge, measured perpendicular to the longitudinal axis, is 20-65% of the greatest width of the head portion, the cutting edge including two major cutting edge portions located on opposite sides of the surface generating cutting edge, each major cutting edge portion extending between an axially forward point and an axially rearward point, wherein a distance from each axially forward point to the longitudinal axis is shorter than a distance from each axially rearward point to the longitudinal axis, each major cutting edge portion forming an angle of 5-20° in relation to the tangent line of the cutting edge at the forward point, and wherein each major cutting edge portion extends 0.05-0.20 mm in the longitudinal direction.