To Study The Effect Of Holding Time And Holding Temperature On Hardness And Micro Structure Of Alloy Steel AISI4340

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Volume 1, Issue 1 (October, 2015)
Publication No:
Gagandeep Singh, Rajbir Singh, Randhir Singh
134 x


AISI 4340 steel is a widely-used low-alloy steel that provides an advantageous combination of strength, ductility and toughness. AISI 4340 steel can be heat treated to provide a wide range of hardness values. Important properties such as hardness, strength and toughness are greatly influenced by heat treatment processes. It is widely employed for the production of automobile and machine tool parts such as axle shafts, main shafts, spindles, gears, power transmission gears and couplings. The present work investigates the effect of holding time and holding temperature on hardness and microstructure of AISI 4340 alloy steel at different levels of holding time and temperature. The alloy steel AISI 4340 of circular cross-section has been cut into the specimens to carry out the heat treatment. The different specimens of base alloy are heat treated by Quenching and Tempering to vary the levels of hardness.During tempering three levels are defined for each specimen. Two factors  are selected on the basis  of work piece material, chemical composition and guidelines by the previous research work. Taguchi’s L-9 orthogonal array is selected for plan of experiments. Higher hardness   is observed in workpiece which were quenched but after tempering hardness decreases.


Heat treatment, Hardness, Microstructure.

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