Look up a steel grade: standard, description, typical uses, chemical composition limits (%) and mechanical properties by thickness (yield and tensile strength in MPa, elongation %). Data comes from published catalogues of Taiwanese mills (China Steel, Tung Ho Steel, Tang Eng, Yieh United and others): about 1,300 grades across JIS, ASTM, CNS, EN and SAE, each with its source. One grade can have different specs per product type (hot-rolled, plate, bar, section); each is listed separately. 查鋼種的規範、用途、化學成分與依厚度分段的機械性質；資料來自中鋼、東和、唐榮、燁聯、榮剛、中鋼鋁業、名佳利等鋼廠公開型錄，每筆標明來源。例：SS400、SPCC、A572 Gr.50、S45C。