Pengaruh Post-Weld Heat Treatment terhadap ketangguhan dan perambatan retak fatik baja tahan karat martensitik 13Cr4NiMo

HARIYANTO, Kris, Ir. Jamasri, Ph.D

2005 | Tesis | S2 Teknik Mesin

Penelitian ini bertujuan untuk mengetahui ketangguhan dan tingkat laju perambatan retak akibat pengaruh post-weld heat treatment pada baja tahan karat martensitik yang telah dilakukan proses pengelasan shielded metasl arc welding (SMAW) dengan komposisi kimia logam pengisi (filler metal) sama dengan logam induk. Proses perlakuan panas yang dilakukan adalah pengerasan (quenched), pengerasan dilanjutkan temper pada suhu 600℃/2jam, pengerasan dilanjutkan solution annealed pada suhu 950℃ selama 1jam dan pengerasan dilanjutkan solution annealed pada 950℃ selama 1jam dilanjutkan temper pada 600℃ selama 2jam . Hasil pengujian tarik menunjukkan bahwa kekuatan tarik spesimen solution annealed dilanjutkan temper 71kg/mm² lebih rendah dibandingkan spesimen temper, 81.39kg/mm². Sementara nilai impak spesimen solution annealed dilanjutkan temper sebesar 48 Joule lebih tinggi apabila dibandingkan dengan spesimen temper, 39 Joule. Hasil pengamatan struktur mikro, khususnya perlakuan panas solution annealed dilanjutkan temper dicapai struktur mikro yang seragam dan tanpa ferit delta, sementara perlakuan panas pengerasan dilanjutkan temper dihasilkan struktur mikto martensit temper. Dari hasil pengamatan kurva laju perambatan retak, bila dibandingkan dengan perlakuan panas yang lain, menunjukkan bahwa umur lelah perlakuan panas solution annealed dilanjutkan temper meningkat dan dihasilkan laju perambatan retak yang hampir sama antara logam induk, HAZ dan logam las. Nilai (n) = 2.6618 untuk logam induk, 2.5133 untuk HAZ dan 2.8133 untuk logam las dan nilai (C) =3.3823E-10 untuk logam induk, 2.9938E-11 untuk HAZ dan 2.2267E-10 untuk logam las.

The objective of this research is to study the toughness and fatigue crack growth rates of post weld heat treatment (PWHT) effect to the martensitic stainless steel, welded with the shielded metal arc welding (SMAW) process using the same filler metal chemical composition as base metal. The region coresponding to the base metal, heat affected zone (HAZ) and weld metal were studied. The post weld heat treatment processes were included oil-quenched, quenched with tempered at 600℃/2h, quenched with solution annealed at 950℃/1h and quenched with solution annealed at 950℃/1h continued tempered at 600℃/2h The result of tensile tests shows that the tensile strength of specimen that was solution annealed continued tempered is 71kg/mm², which is lower than the specimen was tempered, 81.39kg/mm². On the other hand, the impact Charpy value of specimen was solution annealed continued with tempered is 48 Joule, that is higher in comparison with the specimen that was tempered, 39 Joule. The result of microstructure observation, especialy for solution annealed with tempered heat treatment, was obtained uniform microstructure and without delta ferrite, on the other hand quenched with tempered heat treatment have produced tempered of martensite microstructure. In comparison of crack growth rates to the other heat treatment curves reveal that the fatigue life of solution annealed with tempered heat treatment increase, it has the similar crack growth rate between base metal, HAZ and weld metal. The values of (n) is 2.6618 for base metal, 2.5133 for HAZ and 2.8133 for weld metal and the values of (C) is 3.3823E-10 for base metal, 2.9938E-11 for HAZ and 2.2267E-10 for weld metal.

Kata Kunci : Perambatan Retak Fatik,Post Heat Treatment,Baja Tahan Karat,Martensitik, martensitik stainless steel, post weld heat treatment, toughness, crack growth rate