Influence of chromium and niobium content on the mechanical properties and heat affected zone simulations of low-carbon bainitic steels

Abstract. Controlled rolling followed by directing quenching results in steels with excellent mechanical properties, as well as saving cost by passing reheating cost after normalized rolling. The effect of six different combinations of niobium and chromium on microstructures and on mechanical properties of thermomechanically rolled and direct-quenched low carbon microalloyed steel plates were investigated. The target mechanical properties were 700 MPa yield strength with good impact toughness. Bainite was the dominant microstructure of all investigated steels. The prior austenite morphology and transformed microstructure was studied and compared to tensile properties, impact toughness, hardness and hardenability. Also, Gleeble simulation of heat affected zone (HAZ) was performed using t8/5 of 5 s and 15 s to simulate weldability of steels. Four out of six compositions produced similar mechanical properties as S700 steel, which is currently produced in industry. 4 %Cr with 0.035% Nb can get better mechanical properties than with 0.06 % Nb. Addition of Cr also resulted in hardenability of austenite. Decrease of Cr content increased formation of quasi-polygonal ferrite, and therefore increased impact toughness and elongation and decreased the yield strength. Steels with 4% Cr were also observed to have negligible decrease in hardness at coarse grained heat affected zone (CGHAZ) compared to hardness level of base material.Kromi- ja niobipitoisuuden vaikutus mekaanisiin ominaisuuksiin ja hitsaussimulointeihin matalahiilisessä bainiittiteräksessä. Tiivistelmä. Kontrolloitu valssaus yhdessä suorakarkaisun kanssa mahdollistavat teräksille erinomaiset mekaaniset ominaisuudet sekä vähentävät kustannuksia, kun energiaa vievä normalisointivaihe voidaan jättää välistä. Työssä tutkittiin yhteensä kuuden erilaisella niobi- ja kromipitoisuudella olevan koostumuksen vaikutusta termomekaanisesti valssatun ja suorakarkaistun mikroseostetun matalahiilisen teräksen mikrorakenteeseen ja mekaanisiin ominaisuuksiin. Tavoitteena teräksen mekaanisille ominaisuuksille olivat 700 MPa myötölujuus sekä hyvä iskusitkeys. Bainiitti oli dominoiva mikrorakenne kyseisissä mikroseostetuissa teräksissä. Perinnäisen austeniitin morfologiaa ja siihen muodostunutta mikrorakennetta tutkittiin suhteessa mekaanisiin ominaisuuksiin, kuten lujuuteen, venymään, iskusitkeyteen ja karkenevuuteen. Lisäksi hitsattavuutta tutkittiin simuloimalla hitsauksessa syntyvää lämpovyöhykettä Gleeble-simulaattorilla kahdella eri t8/5-ajalla; 5 sekuntia ja 15 sekuntia. Neljällä kuudesta tutkimuksesta koostumuksesta saatiin teollisesti tuotetun S700-teräksen kaltaisia tuloksia mekaanisten ominaisuuksien kannalta. Lisäämällä neljä prosenttia kromia ja 0.035% niobia saatiin parempia mekaanisia ominaisuuksia kuin lisämäällä pelkästään 0.06% niobia. Kromin lisäys myös paransi austeniitin karkenenevutta, kun taas kromin vähentäminen edesauttoi kvasipolygonaalinen ferriitin muodostumista ja siten kasvatti iskusitkeyttä ja venymää myötölujuuden kustannuksella. Lisäksi neljä prosenttia kromia sisältäneiden terästen karkearakeinen lämpövyöhyke pehmeni vähäisesti perusaineeseen verratuna

Biogas Production and Engine Conversion From Diesel Engine to Biogas Engine for Lighting in Rural Area

The research of alternative fuels implemented in internal combustion engines are becoming the subjects of interest nowadays. This paper describes a production of biogas from cow dung, diesel engine conversion process with piston modification of ZH1115 diesel engine. To produce biogas, the usual practice is to mix water with some organic material, such as cow dung (a free source of the appropriate micro-organisms). The slurry is placed in a leak-proof container (called a digester) and leaves it to ferment. After several days at suitable temperature, sufficient methane will have formed to make a combustible gas. Fix dome type of biogas plant is chosen in this gas production for cost saving and to produce sufficient gas at lower temperature. The biogas engine which are modified from diesel engine emphases the ignition system, gas governing and carburetion systems along with a change in compression ratio, in some cases also a change in the combustion chamber. Since diesel engine cannot be operated by biogas alone, this paper covers the conversion of diesel to spark ignition engine i.e. conversion of four stroke of ZH1115 diesel engine to biogas engine based on 30 biogas inlet holes which was recommended by the experienced designers. This paper also describes methods of reducing compression ratio, changing ignition system with timing and fueling system, the comparisons of technical parameters and performance between ZH1115 diesel engine and converted biogas engine. It describes the criteria of technological selections, engineering aspects and short term and long term plans for lighting. The goal to develop and implement BIOGAS engine and use biogas as the renewable energy and bio-fertilizer is to control pollution, to protect environment, to develop rural area and also to reach the ambitious emissions goals and to reduce dependence on imported foreign oil

Application of Electrical Properties to Differentiate Lard From Tallow and Palm Oil

This study aimed to differentiate lard from tallow and palm oil based on its electrical properties, namely conductance, impedance and capacitance. These properties were measured at spectra frequencies of 4.20 to 5.00 MHz in room temperature (26-27 oC). Statistic multivariate that consist on principal component analysis (PCA) and cluster analysis (CA) were used to evaluate the data. The results showed that lard and tallow can be differentiated using whole parameters electrical properties of materials. On the other hand, lard and palm oil can only be differentiated using part of the material electrical properties. Good performance of differentiation process was obtained using PCA model at 4.91 to 4.98 MHz. The first two components of PCA, which was derived from conductance, impedance and capacitance, contributed more than 90% of the total variances. CA showed that lard and tallow are different groups based on the Euclidean distance of each electrical properties. This technique can be potentially developed as an electrical sensor for differentiation lard to tallow and palm oil

Hubungan Antara Kadar Yodium Urin Dan Memori Jangka Pendek Pada Anak Sekolah Dasar Di Daerah Endemis Gaky

Background: Good short term memory ability is essential in order to improve children's academic achievement. Decrease in short term memory function can be found in children on Iodine Deficiency Disorders (IDD) endemic area. Urinary Iodine (UI) concentrations is the recommended method to determine status of IDD endemic area.Aim: To determine the correlation of urinary iodine concentrations and short term memory in elementary school children in IDD endemic area.Methods: This was an analytic observational study with cross sectional design. Samples were 50 elementary school children aged 9-11 years old who lived in IDD endemic area in Sub Kertek, Wonosobo Regency, Central Java Province. Short term memory function was evaluated by Digit Span test. Spot urine samples were retrieved to assess UI concentrations. Spearman test were used for statistical analysis.Results: Median ± deviation standard digit span forward score 4.00 ± 0.89, digit span backward score 2.00 ± 0.35, digit span scaled score 5.00 ± 1.64, and UI concentrations 287.00 ± 64.49 μg/L. There were significant correlation between UI concentrations with digit span forward score (p=0.009) and digit span scaled score (p=0.009) but not significant with digit span backward score (p=0.136)Conclusion: There were positive correlation between UI concentrations and short term memory in elementary school children on IDD endemic area

Pengaruh Teknik Sintesis Terhadap Kualitas Produk Fattyamina Sekunder

Secondary fattyamines has been synthesized by reacting primary fatty amines with acylchlorides and continued with reducing the corresponding secondary fattyamides formed to secondary fattyamines using LiAIH<I'Fatty amines are raw material of natural-based surfactants that can be derived from fatty acids, olefins, or alcohols, of which can be synthesized from natural sources such as palm oil. Conversion of secondary fatty amides to secondary fatty amines was evaluated through the quality of FTIR spectra on wave number of 1639-1645 em' (C=O vibration) and 1544-1555 em" (vibrations of C-H and of secondary amine N-H). Method of synthesis by using closed reflux syncore reactor was better than those of using microwave teflon tubes, and open reflux. The yield of 9 different secondary fatty amines obtainedfrom 5 to 27 replicates by the closed reflux syncore reactor method varied from 17%to 96%

Kajian Implementasi Program Corporate Social Responsibility (CSR) di Daerah Penyangga Taman Nasional Gunung Gede Pangrango (Studi Kasus di Kampung Sarongge Desa Ciputri Kecamatan Pacet Kab. Cianjur)

Forest management in National Park area are related to community development in the buffer zone . This provided an opportunity for stakeholders which is the company \u27s to contributing in national park preservation by Corporate Social Responsibility (CSR) program. This study aims to determine the form and implementation of CSR programs that have been implemented in the buffer zone of Gunung Gede Pangrango National Park, and to know perception and satisfaction of the local community about CSR program at Sarongge Resort. The main program of CSR program is adoption tree, beside that there are also community empowerment program. The results showed that CSR programs in Sarongge Resort still in charity. CSR implemented through a partnership between companies and Green Radio. Public perception of the CSR program is moderate. The level of people\u27s satisfaction of CSR programs are less satisfied

Kajian Ketersediaan Pakan Lebah Madu Lokal (Apis Cerana Fabr.)

Manfaat budidaya lebah madu dalam bidang ekologis yaitu bagi kelestarian flora melalui penyerbukan tanaman maupun keuntungan ekonomis bagi peternaknya dengan produk yang dihasilkan. Penelitin ini bertujuan untuk menginventarisasi ketersediaan pakan lebah madu lokal (Apis cerana Fabr.) di PUSBAHNAS Parungpanjang Bogor.Metode penelitian mengidentifikasi jenis, kerapatan, frekuensi, dominansi dan INP analisis vegetasi di bawahnya melalui observasi lapangan. Hasil penelitian menunjukan ditemukan 9 jenis tanaman kehutanan (25 %), 7 jenis tanaman industri (19,44 %), 15 tanaman buah-buahan (41 %), 2 tanaman sayuran (5,5 %), dan 3 tanaman gulma (8,30 %). kerapatan tertinggi yaitu pada jenis tanaman randu dengan nilai kerapatan 43.75 pohon. Perbedaan nilai kerapatan masing-masing spesies tersebut disebabkan adanya perbedaan kemampuan reproduksi, penyebaran dan daya adaptasi terhadap lingkungan. Nilai frekuensi tertinggi ditemukan pada jenis randu yaitu sebesar 0.75 yang berarti dari total 8 plot yang diamati di lokasi penelitian, 6 plot di antaranya terdapat jensi randu. Jenis lain dengan nilai frekuensi yang relatif tinggi adalah kayu putih yaitu sebesar 0,63 atau ditemukan pada 4 plot dari 8 sampel plot yang diamati, Dominansi tertinggi sebesar 5.79 ditemukan pada jenis randu, sedangkan dominansi terendah sebesar 0.01 terdapat pada jenis pinang

Dynamical Properties of a Haldane Gap Antiferromagnet

We study the dynamic spin correlation function of a spin one antiferromagnetic chain with easy-plane single-ion anisotropy. We use exact diagonalization by the Lancz\H os method for chains of lengths up to N=16 spins. We show that a single-mode approximation is an excellent description of the dynamical properties. A variational calculation allows us to clarify the nature of the excitations. The existence of a two-particle continuum near zero wavevector is clearly seen both in finite-size effects and in the dynamical structure factor. The recent neutron scattering experiments on the quasi-one-dimensional antiferromagnet NENP are fully explained by our results.Comment: 14 pages, SphT/92-135 plain tex with Postscript figures included. Postscipt file available by anonymous ftp at amoco.saclay.cea.fr by get pubs.spht/92-135.ps local_file (290 kb) or get pubs.spht/92-135.ps.Z local_file.Z (compressed - 120 kb