| 摘要 |
PURPOSE: To obtain a process for producing a two-phase stainless steel welded pipe having excellent corrosion resistance of a weld zone in as-welded use. CONSTITUTION: The two-phase stainless steel welded pipe is laser welded in a shielding gas consisting of He or Ar contg. 0.01 to 0.2atm nitrogen under partial pressure at the time of making the pipe by welding using the laser. At this time, the welding is preferably executed under conditions under which the cooling rate V700 of the weld metal obtd. under the following equation at 700 deg.C attains a range of 10 to 900 deg.C/second: V700 =3.02×10<-7> ×(tV/ P)<2> ×(700-T0 )<3> , where t: the thickness (mm) of a blank steel strip, V: a welding speed (m/min), P: a laser output (Kw), T0 : the preheating temp. ( deg.C) at both edges of the blank steel strip. |
