Moh. Miftachul Munir
Politeknik Perkapalan Negeri Surabaya

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Perbandingan PWHT dan Non PWHT pada Pengelasan Material SA-213 Grade T91 dengan SA-213 Grade T22 terhadap Struktur Mikro dan Kekerasan Imam Khoirul Rohmat; Moh. Saiful Amri; M. Habib Muzzakki; Hendri Budi Kurniyanto; Mukhlis Mukhlis; Moh. Miftachul Munir
Jurnal Rekayasa Mesin Vol 18, No 1 (2023): Volume 18, Nomor 1, April 2023
Publisher : Mechanical Engineering Department - Semarang State Polytechnic

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.32497/jrm.v18i1.4171

Abstract

Superheater adalah salah satu komponen boiler yang berfungsi untuk memanaskan uap jenuh yang keluar dari steam drum, material yang sering digunakan pada superheater adalah SA-213 grade T91 dan SA-213 grade T22, pada penelitian ini menggunakan proses pengelasan Gas Tungsten Arc Welding (GTAW). Kedua material yang digunakan wajib dilakukan proses PWHT, karena salah satu tujuan PWHT adalah menurunkan nilai kekerasan dan menyeragamkan struktur mikro. Penelitian ini bertujuan untuk mengetahui perbandingan PWHT dan tanpa PWHT pada material SA-213 grade T91 dan SA-213 grade T22 terhadap struktur mikro dan kekerasan. Hasil pengujian struktur mikro menunjukkan adanya pengurangan prosentase pearlite serta martensite dan adanya penambahan ukuran butir struktur mikro setelah PWHT. Pengujian hardness vickers menunjukkan adanya penurunan nilai kekerasan yang signifikan, khususnya pada daerah weld metal dan HAZ antara material tanpa PWHT dan PWHT. Didapatkan nilai kekerasan tertinggi pada weld metal SA-213 grade T91 tanpa PWHT dengan nilai kekerasan 376.70 HVN dan nilai terendah weld metal ada pada spesimen dengan holding time 45 menit yaitu sebesar 201.1 HVN.
Analysis of Tube Expansion Percentage on Microstructure and Hardness of 316L Stainless Steel Tube-to-Tubesheet Connections with GTAW Process Moh. Syaiful Amri; Bachtiar Bachtiar; Moh. Miftachul Munir; Mukhlis Mukhlis; Muhammad Ari; Ilham Kurniawan
Journal of Mechanical Engineering, Science, and Innovation Vol 5, No 2 (2025): (October)
Publisher : Institut Teknologi Adhi Tama Surabaya, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31284/j.jmesi.2025.v5i2.8161

Abstract

This study analyzes the effect of varying tube expansion percentages on the mechanical properties, microstructure, and hardness of SA-213 TP316L tubes joined to SA-240 TP316L tubesheets in a shell-and-tube type heat exchanger. The tube expansion process was carried out using a roller expander with three expansion levels: 4%, 8%, and 12%, followed by Gas Tungsten Arc Welding (GTAW) at 150 A. Microstructural observations revealed that all joint zones were dominated by austenite with small amounts of delta ferrite, where increasing expansion percentages induced significant changes in the expand area: slight deformation at 4%, grain elongation at 8%, and pronounced grain distortion at 12%. Macrostructural observations showed perfect fusion between the tube and tubesheet for all variations, with no macro defects such as lack of fusion or porosity. Vickers hardness testing indicated the highest values in the expand area for all variations, with a maximum of 377 Kgf/mm², exceeding the standard limit of 250 Kgf/mm² for stainless steel. The hardness of the base metal was around 180 Kgf/mm², while the weld metal ranged from 220–230 Kgf/mm² due to delta ferrite formation. The increase in hardness in the expand area was attributed to cold working effects, indicating that post-tube expansion heat treatment is necessary to reduce residual stresses and restore the optimal mechanical properties of the material.