工字型钢不论是普通型还是轻型的，由于截面尺寸均相对较高、较窄，故对截面两个主袖的惯性矩相差较大，因此，一般仅能直接用于在其腹板平面内受弯的构件或将其组成格构式受力构件。
I-steel whether ordinary or light, because the section size are relatively high and narrow, so the moment of inertia of the main secti of the two sleeve is large, therefore, generally only can be directly used in the web plane bending member or the of lattice stress components.
H型钢是一种断面力学性能较工字钢优良的经济型断面钢材，因其断面的形状与英文字母“H”相同而得名。热轧H型钢的翼缘比工字钢宽、侧向刚度大、抗弯能力强。同等规格下H型钢理重较工字钢轻。
H steel is a kind of economical section steel with better section mechanical properties than that of I-steel. Because the shape of the section is the same as that of the English letter "H". The flange of hot rolled H steel is wider than that of I-steel, large lateral stiffness and strong bending resistance. Under the same specification, the weight of H steel is lighter than that of I-steel.
型材按使用部门分类有铁路用型材（钢轨、鱼尾板、道岔用轨、车轮、轮箍）、汽车用型材（轮辋、轮胎挡圈和锁圈）、造船用型材（L型钢、球扁钢、Z字钢、船用窗框钢）、结构和建筑用型材（H型钢、工字钢、槽钢、角钢、吊车钢轨、窗框和门框用材、钢板桩等）、矿山用钢（U型钢、槽帮钢、矿用工字钢、刮板钢等）、机械制造用异型材等。按断面尺寸大小分类。一般认为，单重在5kg/m以下的是小型材，单重在5～20kg/m的是中型材，单重超过20kg/m的是大型材。
按***用途分，有油桶用板、搪瓷用板、弹板用板等；按表面涂镀层分，有镀锌薄板、镀锡薄板、镀铅薄板、塑料复合钢板等。
According to professional use, there are oil board, enamel plate, bulletproof plate and so on. According to surface coating, there are galvanized sheet, tin plate, leaded sheet, plastic steel plate and so on.