Pearlite

About: Pearlite is a research topic. Over the lifetime, 6028 publications have been published within this topic receiving 65695 citations.

Tensile stress-strain analysis of single-structure steels

Abstract: In an effort to establish a universal model to predict the mechanical properties from processing conditions, tensile tests have been conducted of four single-structure steels, namely, ferrite, pearlite, bainite, and martensite; the data obtained were analyzed in terms of the Ludwik, Hollomon, and Swift equations to characterize their work-hardening behavior It was found that the differential Crussard-Jaoul (C-J) analysis, based on the Ludwik equation, can describe the work-hardening behavior of these steels fairly well The differential C-J analysis has shown that the ferrite and pearlite steels deform with two stages of work hardening, each stage associated with a distinctive value of the work-hardening exponent n Martensitic steels exhibit single-stage work hardening In bainite, the behavior was found to be dependent on transformation temperature; upper and lower bainite exhibit a behavior similar to pearlitic steels and quenched martensite, respectively This can be well understood in terms of the similarity of the corresponding microstructures On the basis of these results, the work-hardening behavior of single-structure steels falls into four categories, according to the n value This classification may serve as a useful guide to predict the flow behavior of steels with a known microstructure or to judge the microstructure merely by stress-strain curves, without microstructural observations

The Crystallography and Nucleation of Pearlite

Abstract: By choice of a suitable iron—manganese—carbon alloy it has been possible to study pearlite nodules growing in austenite, without the austenite transforming on cooling to room temperature. Thin foil electron microscopy has been used to examine the orientation relations between cementite, ferrite and austenite as well as morphological aspects of the transformation. It is shown that one of the classical ferrite—cementite orientation relations found in pearlite (Pitsch—Petch) arises when the pearlite colonies nucleate on ‘clean’ austenite grain boundaries. The other familiar relation (Bagaryatski) arises when the colonies nucleate on pre-existing hyper-eutectoid cementite layers at the austenite grain boundaries. Some observations are made on the mode of nucleation of the pearlite nodules.

High strength low alloy structural steels

Abstract: The development of high strength low alloy structural steel has been a remarkable achievement in the field of metallurgy and is of great interest to both the producers and users of structural steels. Higher strength of the steel permits lighter constructions to be made with thinner sections giving rise to steel economy, increase of payload of transport vehicles and a greater utilisation of the design advantages. Of the various techniques available to enhance the properties of structural steels, addition of grain refining and precipitation hardening elements, niobium, vanadium and titanium, to low carbon steels and their controlled rolling or normalising have been found most advantageous. The alloying element required for making these steels is in micro-quantities and a large part of the strength is derived through grain refinement, which also contributes towards toughness. Various factors that control the properties of structural steels such as the effect on strength of the element in solid solution, ferrite grain size, strengthening by precipitation in ferrite, dislocation strengthening and pearlite volume and its fineness, have been discussed. Results of laboratory scale experiments carried out in NML have been summarised. Results of industrial scale trails on the production and controlled rolling of niobium steels carried out in Rourkela Steel Plant have been discussed. (Dr. S.S. Bhatnagar, Shri B.K. Guha, Shri R.K. Sinha; Scientists, National Metallurgical Laboratory. Dr. N.S. Datar, General Superindentent, Rourkela Steel Plant. Dr. R. Chattopadhyay, former Scientist, National Metallurgical Laboratory)