①為型材C含量;C≤0.25%,闆材t≤40mm;C≤0.26%,闆材40<t≤65mm,棒材t≤20mm;C≤0.27%,闆材65<t≤100mm,棒材20<t≤40mm;C≤0.28%,棒材40<t≤100mm;C≤0.29%,闆材、棒材t>100mm
②表中Si含量,型材t>75mm,闆材t>40mm;Si≤0.4%,型材t≤75mm,闆材t≤40mm,棒材t≥20。
③表中Mn含量,型材t>75mm;Mn: 0.80~1.20%,闆材20<t≤65mm;Mn: 0.85~1.2%,闆材t>65mm;Mn: 0.60~0.90%,棒材t>20。對于型材t≤75,闆材、棒材t≤20mm,Mn含量不作規定。
注:t-型材翼緣寬度、闆材厚度、棒材直徑或對邊距