摘要 |
Utilizing the chemical composition of a steel plate, a low-oxygen welding flux, and a low carbon welding wire, seam welding is conducted by submerged arc welding so that the resulting weld metal has a chemical composition, in which PWM value defined as below is in a range of from 0.18 to 0.33, and a micro-structure containing acicular ferrite not less than 55% by area ratio: <MATH> where, <MATH> Furthermore, when cracking resistance is required, submerged arc welding is conducted such that the chemical composition of the weld metal satisfies Prh value of less than 2.8, in addition to fulfilling the above conditions: <MATH> <IMAGE> |