This standard specifies the measurement objects, measurement tools, measurement platforms, measurement methods, measurement result calculations and measurement reports for bar bending. This standard applies to the measurement and evaluation of the curvature of hot-rolled steel bars (hereinafter referred to as bars). Not suitable for measurement of "S"-shaped bending and torsional bending. The measurement of the curvature of forged bars, cold-drawn bars, and cold-drawn bars may refer to this standard.