Abstract
Quenching and tempering are processes that strengthen and harden materials like steel and other iron-based alloys. Conventional heat treatment procedures for producing martensitic steels generally involve continuous and rapid cooling of an austenitized specimen in some types of quenching media such as water, oil, or air, in which the properties of steel quenched depends largely on the properties of these quenching media. Four vegetable oils: Cotton seed oil, Neem seed oil, Shea butter oil and Palm kernel oil, were blended into two different samples, namely Blend A: Cotton seed oil and Neem seed oil and Blend B: Cotton seed oil, Neem seed oil, Palm kernel oil and Shear butter oil. These were mixed in different ratios. Samples of Medium Carbon Steel were heated to 850°C and soaked for 10 minutes inside a Muffle Furnace before quenching in the prepared quenching media. The Microstructure and mechanical properties of the samples were investigated to determine the quenching performance of the Vegetable Oil Blends. The results showed that Blend A1 produced best properties for the Impact Strength and Yield Strength with values of 0.82 J/mm² and 429.71N/mm² respectively. On the other hands, Blend A2 quenched Steel had best properties for the Hardness and Tensile Strength with 52.8 HRA and 892 N/mm² respectively. Microstructure analysis also confirms improved hardness and toughness exhibiting more martensite for blend containing the four oils than blend with only two oils.
Highlights
Quenching operation belongs to the processes of heat treatment, for which the highly intensive and dynamic heat transfer at the surface of the body occurs
The choice of effective quenching medium after heat treatment is very critical in ensuring the achievement of desired mechanical properties; selection of a quenchant depends on the quench sensitivity of a particular grade of steel and the severity of quench medium (Buczek and Telejko, 2004, Feng and Tahir, 2008)
It was established that vegetable oils can be used as quenching medium for medium carbon steel since the mechanical properties of the samples quenched using the blending of different oil indicates an improved properties which depends on different combination and mixing ratios 2
Summary
Quenching operation belongs to the processes of heat treatment, for which the highly intensive and dynamic heat transfer at the surface of the body occurs. Comparisons of different quenchants in heat treatment processes of steels are of great importance in order to achieve desired hardness, strength or toughness and minimizing the possibility of occurrence of quench cracks due to evolution of residual stresses (Totten, Howes and Maurice, 1997). The choice of effective quenching medium after heat treatment is very critical in ensuring the achievement of desired mechanical properties; selection of a quenchant depends on the quench sensitivity of a particular grade of steel and the severity of quench medium (Buczek and Telejko, 2004, Feng and Tahir, 2008). The third stage known as convective cooling stage begins when the temperature of the metal surface is reduced below the boiling point of the quenching liquid; cooling rate is low during this stage (Buczek and Telejko, 2004, Gorysushin et al, 1991)
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