I don't know the meaning, but if you look in the ASTM standard (probably A356 or A216, I don't have the book in front of me), you will find that there is also a WCA and a WCC. For low-temperature sevice there are LCA, LCB and LCC. There are slight variations in the compositional and strength requirements between each alloy in the series.
Oops, soory, slight slip of the finger on the last reply. It should have been A352, not A356. Having seen the book, I think I can hazard a guess at the meanings of the letters. A216 is entitled Steel Castings, Carbon, Suitable for Fusion Welding, for High Temperature Service. A352 is Steel Castings, Ferritic and Martensitic, for pressure containing parts, Suitable for Low Temperature Service.
My guess is that the W or L refer to Welding or Low Temperature, C for casting, and the A, B and C for the position in the series.
these are the gardes defined in ASTM/ASME A216 has three grades viz.. WCA, WCB & WCC for carbon steel castings
with slight variations in chemical/mechanical values
for WCB
c 0.3%
Mn 1%
P 0.04%
S 0.045%
si 0.6% all are Max and other specified residual elements
with 485-655 Mpa UTS, 250Mpa YS Min and El% of 22 Min
