Effect of Heat Treatment on Low Carbon Steel: An Experimental Investigation

Abstract

In engineering metallurgy, heat treatment of steels is one of the most important factors as it enhances various physical and mechanical properties which are considered handy in numerous structural applications. Heat treatment is basically the combination of operations involving the heating and cooling of a metal or alloy in solid state for obtaining required microstructures by refining the grain size and a combination of properties. The prime object of this investigation is to illustrate the effect of heat treatment on low carbon steel (AISI 1020) to expose its mechanical (hardness) and microstructural (microstructures) properties. For this purpose, cylindrical shaped AISI 1020 steel specimens were used. The samples were polished using a specimen polishing machine and heated in a heat treatment furnace at approximately 950°C for almost 2 hours and then cooled by different quenching media (Water, Air, Ash). After heat treatment (Hardening, Normalizing, Full Annealing) the Brinell hardness number (B.H.N) was determined using a Universal testing machine (U.T.M) and the microstructures were examined using a metallurgical microscope. It was observed that, due to hardening the resultant structure was a super saturated solid solution of carbon trapped in a body centered tetragonal structure called martencite which increased the hardness number of the steel specimens drastically making an extreme harder steel. Moreover, full annealing provided lower hardness value due to the presence of ferrite structure and normalizing provided moderate hardness value and ductility due to slow cooling.

Evaluation of combined heat treatment techniques of testing hardness and tensile strength of mild carbon steel commonly used in Nigeria

“…The later pair of figures still being higher than the values of the asrolled material. The result is consistent with the effect of tempering, which is normally used to relive internal stress, reduce brittleness (Hasan, 2015;and Rahman et al, 2016) and hence, tough to resist shock and fatigue. On the other hand, Figure 4 shows that when the carbon steel was normalized and quenched at 850 °C and then tempered at the same temperatures as in the preceding process, the hardness and tensile strength still reduced gradually from 400 HB and 1320 N/mm 2 , respectively at tempering temperature of 250 °C to 248.3 HB and 819 N/mm 2 , respectively, at tempering temperature of 600 °C.…”

“…Therefore, it is important to know about the nature of austenite and its transformation on heating before proceeding on the heat treatment of metals. Heat treatment is basically the combination of operations involving the heating and cooling of a metal or alloy in solid state for obtaining required microstructures by refining the grain size, shape and distribution and a combination of properties (Rahman et al, 2016;and Białobrzeska, 2017). It is on this basis that carbon steel test treatment is of paramount importance and, hence, in this study some combinations of heat treatment procedures were employed as a means of testing the hardness and tensile strength properties of the carbon steel commonly used in Nigeria.…”

Perlakuan Panas Bertingkat Sebagai Upaya Meningkatkan Kekuatan Mekanik Baja Karbon Rendah

“…Pada proses tempering terjadi penurunan kekerasan dikarenakan perlambatan pendinginan yang dilakukan sehingga specimen uji menjadi lebih ulet. (Rahman, Karim, & Simanto, 2016).…”

Effect of quenching media on microstructural evolution, mechanical and wear properties of AISI4135 steel

“…Hence, the heat treatment of steels is considered as one of the important processes for obtaining the desired microstructures and properties. 4 New processes have been developed over the years to control the structure-properties relations and to produce high strength steels such as sintering, rolling, extrusion, powder metallurgy etc. [5][6][7] But thermal processing has to be carried out to better match the properties and microstructures.…”