Abstract
The medium carbon low nickel chromium steel is a widely used high strength low alloy steel that provides an advantageous combination of strength, hardness, toughness and ductility for machine part members. It has been widely used for fabrication of parts like gears, cams, piston rods and shafts to name a few. This steel may be subjected to general conventional heat treatments to substantially alter its mechanical characteristics. The typical microstructure of hardened steel shows a martensitic matrix responsible for its strength and wear resistance. Before hardening and tempering, normalizing heat treatment was given to standardize the microstructure. In this study tensile, microstructure and hardness specimens were prepared and subjected to Hardening and Tempering heat treatment. The tensile strength of each specimen including the as-received was tested in an electronic tensometer. Microstructures were recorded on heat treated as well as untreated conditions. Rockwell hardness test was performed on each of the hardness specimen including the as-received one.
Highlights
Steel is an alloy of Iron and Carbon
Alloying and heat treatment are two methods which are extensively used for controlling material properties
It has already been inferred that the steel on heat treatment can undergo morphological changes to obtain different mechanical properties
Summary
Steel is an alloy of Iron and Carbon. Carbon is present in steel in combined form like cementite. An attempt has been made to study the effect of variation of process parameters such as holding temperature, holding time and type of heat treatment on the hardness, tensile properties and microstructure of medium carbon low nickel chromium steel. The high temperature phase austenite in steel has the property to transform into variety of room temperature phases like coarse pearlite, sorbite, troostite, bainite & martensite depending upon the cooling cycle [7,8]. These phases may be the decomposition products like ferrite & cementite or it may be super saturated solid solution known as martensite [9]. The values of hardness tabulated are obtained for a load of 100N, making use of a 1/16 inch steel ball indenter
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