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S. CVETKOVSKI et al: OPTIMIZATION OF WELDING PARAMETERS FOR GAS TRANSPORTATION STEEL PIPES Figure 8 Microstructure of the locations presented on Figure 7, a. weld metal, b. penetratration between the welds, c. CGHAZ, d. FGHAZ, e. ICHAZ, f. base metal fine grained microstructure, magnification x200, etched in Nital The weld metal shows mixed type of fracture, containing both areas of brittle and ductile fracture (see Figure 9b). It was observed that the micro crack found in this region is parallel to the proeutectoid ferrite, marked with black arrow. Testing of mechanical properties was performed according to GOST 20295 7. These investigations concerns segments 7-11 from Series III. Generally the following values are obtained Re = 389-403 N/mm 2 , Rm= 519-531 N/mm 2 , A5 = 27-31% and KU = 106-125 J, at -40 o C. Hardness measurements (Vickers method) were performed on the cross section containing base metal and weld joint. The measurements were defined in a way to investigate all characteristic zones of welded joint. In summary, it can be said that the lowest hardness values were recorded in the base metal (145-160 HV) because of the low carbon content, while the highest values were found in the weld metal (200 HV). It should be noted that increase in hardness in the HAZ was not recorded. Generally, the highest measured value is 202 HV, which is much lower than 300 HV that is treated as a critical value for this type of steels 10. CONCLUSIONS Experiments showed that increase of the welding current improved penetration. Increasing of arc voltage resulted in a broadening of the weld face without a significant influence to the penetration, while the increasing of the welding speed lowers the welds. The best Figure 9 Fractured surface (segment 7 Serie III), a. base metal, b. weld metal properties were found in the sample 7 (Series III) welded with the following parameters: wire I welding current 680 A, arc voltage 32 V. Wire 2 welding current 580 A, arc voltage 40 V. Welding speed is 1,4 m/min. Torches inclination: 90° for the first and 60° for the second wire. Performed welding with self made equipment (serie II) didn’t satisfy requirements. Pure welds quality and bed geometry was obtained. So improving weld properties and geometry, using this equipment will be the main target in our next investigation. REFERENCES 1 American Petroleum Institute: Recommended pipeline maintenance welding practices. API RP 1107, USA. 2 G. Tither and W. E. Lauprecht, Pearlite-reduced HSLA steels for line pipe, Metal Science and Heat Treatment, December 07, 2004. 3 V. N. Marchenko and B. F. Zin’ko, Current trends in the development and production of steels and pipes for gas and oil pipelines; Translated from Metallurg, (2008) 3, 49-55. 4 American Petroleum Institute: API 5L standard 5 Lincoln Electric, Welding Handbook 6 Linde ELLIRA handbook, 1988. 7 Standard GOST 20295/85 8 G: M: Evans, N Bailey, Metallurgy of Basic Weld Metal; Abington Publishing, TWI, Cambridge England 1997. 9 Norman Bailey, Weldability of Feritic Steels, Abington Publishing, TWI, Cambridge, England 1994. 10 S. Shanmugam, R.D.K. Misra, J. Hartmann and S.G. Jansto, Microstructure of high strength niobium-containing pipeline steel, Materials Science and Engineering, 441(2006) 1-2, 215-229. ACKNOWLWDGMENT - The part of this study was conducted under support of Ministry of Science and Technological Development, Republic of Serbia Note: English language lecturer: Biljana Mostrova, Faculty of Technology and Metallurgy, Skopje. 334 METALURGIJA 49 (2010) 4, 331-334
A. YASAR EFFECTS OF ALCOHOL-GASOLINE BLENDS ON EXHAUST AND NOISE EMISSIONS IN SMALL SCALED GENERATORS INTRODUCTION The increasing industrialization and motorization of the world has led to a step rise for the demand of petroleum-based fuels. Petroleum-based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain regions of the world. Therefore, those countries not having these resources are facing energy/foreign exchange crisis, mainly due to the import of crude petroleum. Hence, it is necessary to look for alternative fuels which can be produced from resources available locally within the country such as alcohol, biodiesel, vegetable oils etc. 1. The simple approach to the use of alcohols in spark ignition (SI) engines is to blend moderate amounts of alcohols with gasoline. The second and more technically challenging option is to use alcohols essentially neatly as engine fuel 2. Alcohols such as methanol (CH3OH), butanol (C4H9OH) and ethanol (C2H5OH) have received considerable attention recently because they are considered as highly efficient, and low-polluting future fuels through their lean operating ability 3. Alcohol burns cleaner than regular gasoline and produce lesser carbon monoxide, HC and oxides of nitrogen 4. Alcohol has higher heat of vaporization; therefore, it reduces the peak temperature inside the combustion chamber leading to lower NOx emissions and in- Received – Prispjelo: 2009-09-18 Accepted – Prihva}eno: 2009-11-30 Preliminary Note – Prethodno priop}enje In this study, the effect of methanol or butanol addition to gasoline on exhaust emissions and noise level has been experimentally investigated. Results showed that the concentrations of CO and NOx emissions were decreased depending on the higher alcohol contents and the carbon monoxide concentration of gasoline was higher than that of methanol or butanol-gasoline blends for all engine loads. It was determined that content of the HC was decreased at higher engine load but noise level was increased. Key words: environmental protection, exhaust emissions, alcohol-gasoline blends, generators Djelovanje alkoholno-benzinskih mje{avina na emisiju ispu{nih plinova i buke kod malih generatora. U ovom radu eksperimentalno je ispitano djelovanje dodataka mentola ili butanola u benzin na emisije ispu{nih plinova i na razinu buke. Rezultati su pokazali smanjenje koncentracije emisija CO i NOx, ovisno o ve}im udjelima alkohola. Koncentracija CO kod benzina bila je vi{a nego kod mje{avina benzina i metanola ili butanola, za sva optere}enja motora. Utvr|eno je da je pri ve}em optere}enju motora sadràj CH smanjen, ali je pove}ana razina buke. Klju~ne rije~i: za{tita okoli{a, emisije ispu{nih plinova, mje{avine alkohol-benzin, generatori A. YASAR, Faculty of Technical Education, Mersin University, Tarsus, Turkey ISSN 0543-5846 METABK 49(4) 335-338 (2010) UDC – UDK 502.72:628.512:661.72:621.431.36=111 creased engine power. The oxygen presence in alcohol fuel provides soot-free combustion with low particulate level. Methanol’s most desirable features its high octane quality. Methanol rates 106-115 octane numbers by the research method and 88-92 octane numbers by the motor octane method 5. Because of these characteristics, methanol is considered to be one of the most likely alternative automotive fuels for SI engines in the foreseeable future 6. Iso-butanol (C4H9OH) is an attractive alcohol fuel because of its high heating value compared to methanol and ethanol. Iso-butanol heating value represents 77 % of gasoline heating value, and it has the advantages of a low affinity for water solubility in blends 7. The high octane number of iso-butanol makes it inherently adaptable as fuel for conventional spark ignition engine 8. Various studies were performed related to the usage of alcohols-gasoline blends in spark ignition engines. The effect of methanol and butanol addition to gasoline on brake specific fuel consumption (b.s.f.c.), exhaust gas temperature, and thermal efficiency has been experimentally investigated 9. The performance measurements show that there is an increase in b.s.f.c. when using alcohol-gasoline blends, and b.s.f.c. of a butanol-gasoline blend is less than for a methanol-gasoline blend. The experimental results show that the engine thermal efficiency was decreased when fueled with alcohol-gasoline blends. Alasfour 10 investigated the ef- METALURGIJA 49 (2010) 4, 335-338 335
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