弯曲度：工字钢高度小于或等于400MM时，每米弯曲度不得大于1.5MM，总弯曲度不得大于总长度的0.15%。高度大于400MM时，每米弯曲度不得大于1.0MM，总弯曲度不得大于总长度的0.1%。

Bending degree: when the height of the I-steel is less than or equal to 400MM, the bending degree of each meter must not be more than 1.5MM, and the total bending degree should not be more than 0.15% of the total length. When the height is greater than 400MM, the bending degree of each meter must not be more than 1.0MM, and the total bending degree should not be more than 0.1% of the total length.

不同于普通工字型的是H型钢的翼缘进行了加宽，且内、外表面通常是平行的，这样可便于用高强度螺栓和其他构件连接。其尺寸构成合理系列，型号齐全，便于设计选用。（除了吊车梁用工字型钢）。

Unlike the ordinary I-type, the flange of H steel is widened, and the inner and outer surfaces are usually parallel, so that it can be easily connected with high-strength bolts and other components. Its size is a reasonable series, and the model is complete, which is convenient for the design. (except for crane girder with I-type steel)

随着科学技术和工业的发展，对材料提出了更高的要求，如更高的强度，抗高温、高压、低温，耐腐蚀、磨损以及其它特殊物理、化学性能的要求，碳钢已不能完全满足要求。

With the development of science and technology and industry, the material has put forward higher requirements, such as higher strength, high temperature, high pressure, low temperature, corrosion resistance, wear and other special physical and chemical properties, carbon steel can not fully meet the requirements.