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All Journal Rekayasa Mesin Journal of Materials Exploration and Findings Metalurgi
Myrna Ariati, Myrna
Department Of Metallurgy And Materials Engineering, Universitas Indonesia
Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering

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Effect of Austenization and Repeated Quenching on The Microstructures and Mechanical Properties of Wear-Resistant Steel Nugraha, Yanuar; Mochtar, Myrna Ariati
Journal of Materials Exploration and Findings Vol. 1, No. 3
Publisher : UI Scholars Hub

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Abstract

This study was focused on determining the effect of repeated austenitization and quenching on mechanical properties and microstructure. The experiment was carried out in a rolled quencher facility with a heat treatment process of one to two times, with parameters of an austenizing temperature of 9500C and quenching at a temperature of 8500C with pressurized water media. Testing of specimens, including microstructure observations and hardness testing. The repeated heat treatment process showed an increase in hardness of 0.79% on one-time repeated heat treatment and 1.65% on two repeated heat treatments. This occurs due to the presence accompanied by refinement of the prior austenite grains and the martensite structure. In addition, the hardness value decreases in the surface area 17.9 HV and 24.9 HV due to the deeper accumulation of decarburization 0.06-0.10 mm followed by thicker iron oxide growth 0.04-0.07mm.
The Effect of Parameters in Cryogenic Treatment on Mechanical Properties of Tool Steel: A Review Ekaputra, Ronaldus Caesariano; Mochtar, Myrna Ariati
Journal of Materials Exploration and Findings Vol. 2, No. 3
Publisher : UI Scholars Hub

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Abstract

Tool steel is classified as special alloy steel which proposed as dies or mold materials as their high mechanical properties and dimensional stability. In order to improve tool steel’s mechanical properties, heat treatment process, especially, cryogenic treatment is conducted. Cryogenic treatment is done by exposing tool steel material at sub-zero liquid/gas media after heated at austenite temperature. This process significantly affects the martensite phase transformation increase and avoids retained austenite emersion. In particular, the higher martensite volume fraction, the higher hardness and wear resistance value of tool steel. It had been proven that adjusting critical process parameters of cryogenic treatment (temperature process, soaking period, and tempering process) shall increase the efficiency of improving mechanical properties of cryo-treated finished product.
THE EFFECT OF PYROLYSIS DURATION ON THERMAL CONDUCTIVITY, STABILITY, AND VISCOSITY OF DISPERSED PCB-BASED PARTICLES IN THERMAL FLUID Putra, Wahyuaji Narottama; Ariati, Myrna; Suharno, Bambang; Ferdian, Deni; Ulum, Reza Miftahul
Jurnal Rekayasa Mesin Vol. 14 No. 3 (2023)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v14i3.1655

Abstract

Solid particles have a higher thermal conductivity compared to a fluid. Therefore, it is a common practice to disperse solid particles inside a base fluid to increase its thermal conductivity. The particle-dispersed fluid is called a thermal fluid. Thermal fluid, such as a coolant, is widely used as a heat transfer fluid. Several types of particles can be used to increase the thermal conductivity of the fluid, i.e., metallic particles, metal-oxide particles, or even carbon-based particles. In this research, a carbon-based particle was used as the dispersed particle. The particle was obtained by processing electronic waste, specifically Printed Circuit Board (PCB). The PCB was pyrolyzed for variable duration at 15, 30, and 45 minutes to increase the carbon content. After pyrolyzing, the particle was milled to reduce its size. Subsequently, the PCB particle was added to distilled water. Sodium Dodecylbenzene Sulfonate (SDBS) was added as a surfactant to increase fluid stability and prevent particle agglomeration. Thermal conductivity was improved by up to a 13% increase at the 15-minute pyrolysis. Adding SDBS surfactant also improves the thermal fluid's stability to -29,1 mV. The fluid's viscosity was slightly increased up to a maximum of 0.984 mPa.S.
EFFECT OF COOLING-MEDIUM INDUCED INITIAL STRUCTURE BEFORE INTERCRITICAL ANNEALING ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF LOW ALLOY DUAL-PHASE STEEL Romijarso, Toni Bambang; Rohmah, Miftakhur; Ariati, Myrna; Mabruri, Efendi; Siradj, Eddy Sumarno
Metalurgi Vol 38, No 2 (2023): Metalurgi Vol. 38 No. 2 2023
Publisher : National Research and Innovation Agency (BRIN)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.55981/metalurgi.2023.727

Abstract

The present research focused on determining the effect of cooling-medium-induced initial structure before the intercritical annealing induced dual-phase structure in the low alloy steel. Low carbon steel, which consists of containing 0.09 wt.% C was heated at 920 °C for 30 minutes to austenitization and then cooled in various media to provide the different initial structures before the IA (intercritical annealing) process. After austenization, the cooling process in the furnace and open-air provided a ferrite-pearlite phase, while the cooling process in water generated full martensite as the initial structure. Afterwards, the sample was intercritical-annealed at 750 °C (temperature between Ac1 and Ac3 lines or intercritical zone) for 10 minutes and then quenched in water. The water quenching after the austenitizing process improved the mechanical strength of steel (919 MPa), compared to the as-received state (519 MPa) due to martensite formation. As the cooling rate increased after the austenitizing process, the tensile strength increased and the elongation decreased. The different structures before intercritical annealing affected the martensite volume fraction and further correlated with improving mechanical properties. The ferrite and pearlite, as the initial structure before the IA process, provide a smaller fraction of martensite (18.36 vol.% for furnace cooling and 27.85 vol.% for open-air cooling). In contrast, the full martensite as the initial structure before IA generates a higher fraction of martensite (39.25 vol.%). The tensile strengths obtained were 512, 516, and 541 MPa with elongations of 29.8%, 30.1% and 32.6% for cooling furnace, open air and water, respectively. The strain-hardening behavior during the intercritical annealing is not affected by the initial process of the structure.
THE EFFECT OF PYROLYSIS DURATION ON THERMAL CONDUCTIVITY, STABILITY, AND VISCOSITY OF DISPERSED PCB-BASED PARTICLES IN THERMAL FLUID Putra, Wahyuaji Narottama; Ariati, Myrna; Suharno, Bambang; Ferdian, Deni; Ulum, Reza Miftahul
Jurnal Rekayasa Mesin Vol. 14 No. 3 (2023)
Publisher : Jurusan Teknik Mesin, Fakultas Teknik, Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21776/jrm.v14i3.1655

Abstract

Solid particles have a higher thermal conductivity compared to a fluid. Therefore, it is a common practice to disperse solid particles inside a base fluid to increase its thermal conductivity. The particle-dispersed fluid is called a thermal fluid. Thermal fluid, such as a coolant, is widely used as a heat transfer fluid. Several types of particles can be used to increase the thermal conductivity of the fluid, i.e., metallic particles, metal-oxide particles, or even carbon-based particles. In this research, a carbon-based particle was used as the dispersed particle. The particle was obtained by processing electronic waste, specifically Printed Circuit Board (PCB). The PCB was pyrolyzed for variable duration at 15, 30, and 45 minutes to increase the carbon content. After pyrolyzing, the particle was milled to reduce its size. Subsequently, the PCB particle was added to distilled water. Sodium Dodecylbenzene Sulfonate (SDBS) was added as a surfactant to increase fluid stability and prevent particle agglomeration. Thermal conductivity was improved by up to a 13% increase at the 15-minute pyrolysis. Adding SDBS surfactant also improves the thermal fluid's stability to -29,1 mV. The fluid's viscosity was slightly increased up to a maximum of 0.984 mPa.S.
Co-Authors Anne Zulfia Bambang Suharno Deni Ferdian Didi Rooscote, Didi Dwi Marta Nurjaya, Dwi Marta Eddy S Siradj Ekaputra, Ronaldus Caesariano Mabruri, Efendi Miftakhur Rohmah, Miftakhur Nugraha, Yanuar Putra, Wahyuaji Narottama Romijarso, Toni Bambang Ulum, Reza Miftahul