ผลกระทบของไนโตรเจนในก๊าซปกคลุมอาร์กอนที่มีต่อปริมาณเดลต้าเฟอร์ไรท์ใน เหล็กกล้าไร้สนิมออสเตนนิติก เกรด 304L กรณีการเชื่อมทิก

Abstract

The objective of the research work was  to study the  effect  of  nitrogen  in  argon  as  a  shielding  gas  on  delta-ferrite  content in the AISI 304L  austenitic  stainless  steel using Tungsten Inert Gas  (TIG) welding process. A square-plate specimen having the size of 150 mm. and thickness of 4 mm. was welded for 120 mm. long under the shielding gas of Ar₂ which was mixed with N₂ from 0 to 10, 15, 20, 25, 30, 35, 40 and 100%by volume. The weld-bead profile was inspected based on the DIN standard No. 8563.  The results found that (1) increasing of N₂ up to 9% provided the d-Fe in fusion zone decreased whereas in heat affected zone increased; the weld-bead profile was well, (2) increasing of N₂>10% affected on d-Fe in fusion zone increased, and (3) 2-5% of N₂ in Ar₂ was the best composition providing 5-10% 0f d-Fe, good weld-bead profile and without inclusions.