D型管

D型钢按钢管截面形状尺寸的不同又可分为等壁厚D型管(代号为D)、不等壁厚无缝异型钢管(代号为BD)、变直径无缝异型钢管(代号为BJ)。D型管广泛用于各种结构件、工具和机械零部件。和圆管相比，D型管一般都有较大的惯性矩和截面模数，有较大的抗弯抗扭能力，可以大大减轻结构重量，节约钢材。

D-shaped steel can be divided into D-shaped steel pipe with equal wall thickness (code D), seamless special-shaped steel pipe with different wall thickness (code BD) and seamless special-shaped steel pipe with variable diameter (code BJ) according to the shape and size of steel pipe section. D-tube is widely used in various structural parts, tools and mechanical parts. Compared with circular tubes, D-shaped tubes generally have larger inertia moment and section modulus, and have greater flexural and torsional resistance, which can greatly reduce the weight of the structure and save steel. D型管一般是根据断截面来区分的，按材料来说又可分为无缝钢管D型管，铝合金D型管，塑料D型管。下面主要介绍一下钢管D型管。

D-type pipe is generally distinguished according to the broken section. According to material, it can be divided into seamless steel D-type pipe, aluminum D-type pipe, plastic D-type pipe. The following is a brief introduction of the D-shaped steel pipe.

钢管异型管可分为椭圆形异型钢管、三角形异型钢管、六角形异型钢管、菱形异型钢管、八角形异型钢管、半圆形异型钢圆，不等边六角形异型钢管、五瓣梅花形异型钢管、双凸形异型钢管、双凹形异型钢管、瓜子形异型钢管、圆锥形异型钢管、波纹形异型钢管。

The special-shaped steel pipe can be divided into elliptical, triangular, hexagonal, rhombic, octagonal, semi-circular, unequal hexagonal, five-petal plum-blossom, double convex, double concave, melon-shaped, conical and corrugated special-shaped steel pipes.