Temper ing State Grade Carbon equivalent value (CEV)/% Normalthi ckn ess≤63mm Normal thickness or diameter>63 mm - 120 mm Normal thickness>120mm - 150 mm Q345 ≤0.44≤0.48≤0.48 Q390 ≤0.46≤0.48≤0.49 Q420 ≤0.48≤0.50≤0.52 Q460 ≤0.53≤0.54≤0.55 Q500 ≤0.47≤0.48≤0.48 Q550 ≤0.47≤0.48≤0.48 Q620 ≤0.48≤0.49≤0.49 Q690 ≤0.49≤0.49≤0.49 6.1.9 When the carbon content of steels delivered at thermomechanical rolling (TMCP) or thermomechanical rolling + tempering state is no bigger than 0.12%, the solderability of steels may be evaluated by the welding crack sensitivity index (Pcm) in place of carbon equivalent value. Pcm shall be calculated according to Formula (2) on the basis of the heat positions and its value shall meet the provisions of Table 5. Pcm=C+Si/30+M n/20+Cu/20+Ni/60+Cr/20+M o/1S +V /10+5B (2) 7
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