Djoko Suprijanto
Combinatorial Mathematics Research Group, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jalan Ganesa 10 Bandung, Indonesia

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EFFECT OF POST HEAT TEMPERATURE TO HARDNESS AND MACROSTRUCTURE IN WELDED STELL ST 37 Subardi, -; Suprijanto, Djoko; Mahendra, Roza Lyndu R.
T R A K SI Vol 9, No 1 (2009): mechanical engineering
Publisher : T R A K SI

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (71.575 KB)

Abstract

The present study aims to investigate the effect of post heat temperature of hardness andmacrostructure on the result steel welded St 37. Welded process with SMAW (Shelded Metal ArcWelding) and AC-DC current. Plate steel ST 37 welded of longitudinal, than heat treatment withtemperature various: 300°C, 400°C dan 500°C.Highest rate hardness 157,83 kg/mm2 on temperature treatment spesiment 500o cause haveferit grain boundary structure more and homogen so properties more hardness. The lows bendingstrength 43,51 kg/mm2 on raw material, cause have ferit structure and perlit so more soft properties.The micostuctrure welded area arround; ferit graind boundary, ferit widmanstatten, ferit acicularand perlit.
PENGARUH DIAMETER PENGEROLAN DINGIN TERHADAP KEKUATAN BENDING BAJA KARBON RENDAH Suprijanto, Djoko
T R A K SI Vol 11, No 2 (2011): mechanical engineering
Publisher : T R A K SI

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Baja St 41 merupakan baja karbon rendah yang mengandung karbon dibawah 0,30% banyak diaplikasikan untuk konstruksi umum. Pembetukan benda dengan pengerolan banyak dilakukan untuk pembuatan bejana maupun konstruksi penguatan dengan plat baja .Pada penelitian ini dilakukan proses pengerolan dingin, baja AISI 1015 setebal 7,65 mm dengan radius: 500, 1000, 2000 dan 3000 mm. Pengujian yang dilakukan adalah uji komposisi kimia, uji kekerasan uji struktur mikro , dan uji kekuatan bending dengan arah berlawanan dari arah pengerolan. Dari hasil pengujian tersebut dapat disimpulkan bahwa pengerolan akan meningkatkan kekuatan bending sampai pada ukuran tertentu. Setelah Iewat batas tertentu maka bahan akan luluh sehingga menurunkan kekerasan serta kekuatan bendingnya.Kata kunci: Baja St 41, Rolling, Ferit, Kekuatan Bending
The complete list of Ramsey $(2K_2,K_4)$-minimal graphs Wijaya, Kristiana; Baskoro, Edy Tri; Assiyatun, Hilda; Suprijanto, Djoko
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 3, No 2 (2015): Electronic Journal of Graph Theory and Applications
Publisher : GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/ejgta.2015.3.2.9

Abstract

Let $F, G,$ and $H$ be non-empty graphs. The notation $F ightarrow (G,H)$ means that if all edges of $F$ are arbitrarily colored by red or blue, then either the subgraph of $F$ induced by all red edges contains a graph $G$ or the subgraph of $F$ induced by all blue edges contains a graph $H.$ A graph $F$ satisfying two conditions: $F ightarrow (G,H)$ and $(F-e) rightarrow (G,H)$ for every $e in E(F)$ is called a Ramsey $(G,H)-$minimal graph. In this paper, we determine all non-isomorphic Ramsey $(2K_2,K_4)$-minimal graphs.