Corrosion resistance of normalizing heat treatment of carbon steel ck45 in sea water at different velocities
The effect of, normalizing heat treatment on corrosion resistance of carbon steel DIN CK45 is investigated. Test specimens (1.5*1.5*0.3) Cm were manufactured according to ASTM G71 30 Heat treatments (Quenching, and normalizing were performed by heating the specimens in electrical furnace to 850 C and cooling in water for quenching and by air for normalizing microstructure were examined by optical microscope Corrosion tests were investigated by electrochemical potential state cell in prepared salt water (sea water) amulti velocities (1, 2, and 3) m/min where the test specimen represents the positive electrode (anode) pole. Tafle equation was adopted to calculate the corrosion rate. The obtained results show that the heat treatment improves the corrosion resistance by increasing the combination of iron with carbon reducing by that the combination of iron with oxygen which produces rust. Increasing velocity of the media (sea water) contributed in decreasing the corrosion rate because of reducing the assembling of ions on cathode pole Keyword: Heat treatment, Carbon Steel CK45, Corrosion Resistance. Velocity of sea water ~nwbrkl dhlwfll lkatl @mwqm CK45 @Tswb yrrH l`ml hfltkhm `rsb rHbl hld`ml m m msj nysH djm @yjwlwnktl `mjl nd`mlw jtnl @sdnh msq @Slkhl @yrrHl @lm`ml ryth't @srd mt @ysqtl ynwbrk dhlwfl lkatl @mwqm ~l` @ld`mlw DIN CK45 thyH mt d`b'b lkatl rbtkh tny` `ynSt (1.5*1.5*0.3) @fSwm qfw ms ASTM G 71 30 tyrj' @lm`ml nm @yrrHl yf @ld`mw @ysqt dn` yy'brhk nrf @rrH @jrd 850 m deg dyrbtlw @sqml tny`ll ml yf dyrbtl mth `s @dml lkatl rbtkh rj mt kldhkw yy'wDl rhjml mdkhtsb @yrhjml @ynbl SHf rj mt @ld`ml tny`ll whlb yHlml lwlHml mdkhtsb nksl dhjml zhj @Tswb rHbl m `rs @d` dn`w yh 1 2 3 rtm dh @qyqdl yf nsHt djw hyl` lwSHl mt ytl jy'tnl nmw lft @qyrTb lkatl ld`m bsH mtw bjwml bTql tny`l tlthm lwSHl mt ytl rwTl' bbsb @sqml tny`l kldhkw @ld`m @ylm` hl tyrj' ytl tny`ll @bsnlb lkatl @mwqm hsnjtw hyl` lkatl tnwy `mjt lylqt yf hrwdw `rsl @dyz dn` lkatl ld`m yf nsHt djw kldhkw Journal of Engineering and Development, Vol. 17, No.4, October 2013, ISSN 18137822 145 Introduction Rates most metals are in its nature unstable and have the tendency to react with their environments to form a chemical compound to get a more stable state. Medium carbon steel is particularly used in most structural shapes such shafts, gears, dies to cast light metals [1] Corrosion resistance of steels is strongly connected to their microstructure obtained after heat treatments that are generally performed in order to achieve good mechanical properties. For that, there is currently a strong interest in the effect of the heat treatment on the corrosion resistance which is affected by the changes in the microstructure Corrosion can be defined as the destruction of a metal by chemical or electrochemical reaction with its environment. In cooling systems, corrosion causes two basic problems. The first and most obvious is the failure of equipment with the resultant cost of replacement and plant downtime. The second is decreased plant efficiency due to loss of heat transfer. Corrosion occurs at the anode, where metal dissolves. Often, this is separated by a physical distance from the cathode, where a reduction reaction takes place. An electrical potential difference exists between these sites, and current flows through the solution from the anode to the cathode. This is accompanied by the flow of electrons from the anode to the cathode through the metal. Ted Corrosion behavior of metals in sea water is affected by many environmental factors such as water temperature, dissolved oxygen content and velocity The effect of water velocity on metals corrosion behavior has got a great interest by researchers, Kamilia Gruskevica study the effect of water velocity on corrosion resistance of steel pipes finding that the corrosion resistance decreased in low or medium flow media by a percentage between 20 50% than rapid flow. The effect of heat treatment on the microstructure and mechanical properties was, investigated by M.B. Ndaliman (2006) [3] study this under two different quenching medias (water and palm oil) achieving that best proprieties in strength and hardness in water is better than palm oil. Adnan Calic (2009) [4] shows that in different cooling rate ,different microstructure can be obtained and improved it by varying the cooling rate .Thus, heat treatment is used to obtain desired proprieties of such as improving the toughness, ductility or removing the residual stresses, etc. He compared this study with literature survey as, (Bangor and Sachdev, 1982) [5] show that oil quenching produce ferrite martensits phases and thin film of retained austenite. By slow air cooling the results in a large amount in retained austenite in addition to the ferrite and martensite on the other hand with the applied cooling rate increasing the transformed structure evolve s from granular bainite, lower bainite, self tempred martensite, to finally martensite without self tempering (Qiao etal,m2009) [6] .Among them, self tempered martensite obtained in the transformed specimens cooled with of 25 80 C/min, The aim of this paper is to examine the effect of phases which obtained by heat treatment of medium carbon steel CK 45 at different velocities on solution corrosion resistance Journal of Engineering and Development, Vol. 17, No.4, October 2013, ISSN 18137822 146 Experimental Work Metal selection: medium carbon steel CK45 according to DIN specification were chosen because of its wide range of engineering applications such as shafts, molds, connecting rods and its chemical analysis indicated in table (1) which was conducted by ARL Spectrometer.