“…Owing to appropriate weldability and ductility, an improved ethylene pyrolysis furnace tube material involving about 35 mass% Cr, 45 mass% Ni and a total quantity of around 2 mass% Nb, Ti, Zr and W heatresistant cast steel is now extensively used in ethylene pyrolysis furnaces [10,11]. Because of the high carbon content of this type of heat-resistant cast steel, it generally contains a lot of carbides, such as low melting point γ + eutectic carbides, NbC, M 7 C 3 and M 23 C 6 [12][13][14]. For this reason, the weld joint produced from this steel is reported as having a higher weld cracking susceptibility, and most notably a higher hightemperature weld cracking susceptibility than general forged steels [15][16][17].…”