ANALISIS PARAMETER PWHT PADA HASIL PENGELASAN HIGH FREQUENCY WELDING (HFW) MATERIAL X65 TERHADAP HARDNESS DAN STRUKTUR MIKRO

Abstract

Pipelines are one of the main components in the oil and gas industry. One method of
making channel pipes is using the High Frequency Welding (HFW) welding process. The material
used is OD 219 mm x WT 12.7 mm x API 5L L450MO PSL2. In this study, the PWHT process was
applied with temperature variations of PWHT1, PWHT2, dan PWHT3 due to the emergence of
martensite phases in the microstructure of the material. Then several tests were carried out
including hardness, macrostructure, and microstructure testing. The test result of the highest
average hardness value on PWHT test specimens with a temperature parameter of PWHT2 in the
centre weld area of 151.3 kgf/mm 2 . While the lowest average hardness value is found in PWHT test
specimens with a temperature parameter of PWHT3 base metal area of 144.08 kgf/mm 2 . The macro
test results showed that the width of the expanded HAZ was highest in the test specimen with a
temperature parameter of PWHT3 in the ID, MD, and OD regions of 6.3 mm, 11.3 mm, and 12.2
mm respectively. While the lowest expanded HAZ width in the test specimen with PWHT
temperature parameters of PWHT1 with values on ID, MD, and OD of 4.8 mm, 8 mm, and 9.1 mm
respectively. Microtesting showed that there was no change in the microstructure of the weld, HAZ
and base metal areas, but grain roughing and loss of grain orientation in ferrite and pearlite.