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The carbon equivalent is a measure of the tendency of the weld to form martensite on cooling and to suffer brittle fracture. When the carbon equivalent is between 0.40 and 0.60 weld preheat may be necessary. When the carbon equivalent is above 0.60, preheat is necessary, postheat may be necessary.
Use the values in the IIW formula for carbon equivalent: CE = C + Mn/6 + (Cu + Ni)/15 + (Cr + Mo + V)/5 = 0.20 + 0.90/6 + 0 = 0.35. Visit our carbon equivalent calculator to calculate the CE value using other formulae.
P cm is generally used for modern steels typically used for pipeline manufacture, where carbon contents are no more than ~0.11 wt% [7]. However, it should be noted that the P cm formula was derived largely from lower C low alloy steels. The CEN formula was proposed to evaluate the weldability of a wide variety of steels.
PCM. The carbon equivalent PCM is based on Japanese results from Ito and Bessyo in 1969 [7]. It can be used for short cooling times and root welding [8]. Equation: PCM = C + Si/30 + (Mn + Cu + Cr)/20 + Mo/15 + Ni/60 + V/10 + 5*B . CEM
CE is Carbon Equivalent as given in AWS D1.1. Pcm formula is by Japanese Welding Engineering Society’s critical metal parameter: C.E. Weldability. 0.15 Max. Excellent Weldability with all process, No preheat, Interpass or Postheat necessary. 0.15 to 0.30.
Pcm= C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+. Mo/15+V/10+5B (1) Due to widespread application of the carbon equivalent in Japan, the Japanese Welding Engineering Society (JWES) published its own carbon equivalent equation in 1973: CE = Wes. C+Si/24+Mn/6+Ni/40+Cr/5+Mo/4+V/14 (2)
Several different methods of calculating the carbon equivalent exist. The most commonly used are listed below (all values in wt%): The two formulae specified in EN 1011-2: CE = C + 1 ⁄ 6 Mn + 1 ⁄ 5 (Cr + Mo + V) + 1 ⁄ 15 (Ni + Cu) CET = C + 1 ⁄ 10 (Mn + Mo) + 1 ⁄ 20 (Cr + Cu) + 1 ⁄ 40 Ni.
