Influence of Cooling Rate on Final Properties of Laboratory Rolled Products

Abstract

The objective of investigation was to determine the influence of chosen cooling rates after finish rolling on final microstructural and mechanical properties of the laboratory rolled products from steel 42CrMo4. Metallographic analysis showed that microstructure of rolled products, which were after finish rolling cooled down in accelerated manner by water sprays, was composed mostly by hardening phases and by smaller amount of ferrite. Microstructure of the rolled product cooled down in furnace in decelerated manner was formed by pearlitic blocks with minority occurrence of ferrite. Laboratory rolled products cooled down by more complicated modes, which consisted of combination of their cooling by water sprays with subsequent annealing in furnace, showed different phase morphology and distinct band structure. Results of tensile test have proved that the applied modes of cooling of rolled products by accelerated manner had only very small influence on their final mechanical properties. Considerably cooling the rolled product by decelerated manner in furnace resulted in drop yield strength, but on the other hand in an increase of ductility. More complicated modes of cooling the rolled products, which comprised also their annealing, showed the possibilities of significant influencing the strength, and particularly the plastic properties of the steel 42CrMo4.

Quantitative Evaluation of the Microstructure and Mechanical Properties of Hot Rolled 23MnB4 Steel Grade for Cold Upsetting

“…That is why laboratory rolling mills are constructed to illustrate the conditions of the real rolling process in a more detailed way. An example of the above mentioned test can be semi-industrial simulation of manufacturing processes of alloys and metal products (LPS) in IMŻ Gliwice (Institute for Ferrous Metallurgy) [2] and semi-continuous laboratory mill for rolling bars in VSB -Technical University of Ostrava, Faculty of Metallurgy and Materials Engineering, Czech Republic [3]. Potential applications of semi-continuous laboratory are simulations of industrial rolling conditions, choice of optimal process parameters and regulated cooling of steel and alloys non-ferrous alloys.…”

Continuous cooling transformation diagrams of HSLA steel for seamless tubes production

“…various controlled rolling procedures, etc.) but also by the parameters of the final cooling [1][2][3]. The final cooling rate makes it possible to control the austenite softening processes, and phase transformations during decomposition of austenite and grain growth.…”

“…B-Metall. 55 (3) B (2019) 413 -426 controlled transformations and this effect grows with increasing deformation. The interval between A r1 and A r3 temperatures is narrowed up to the true strain of 0.4.…”

The combined effect of chemical composition and cooling rate on transformation temperatures of hypoeutectoid steels

“…In the case of steels in the austenitic region, it is advisable to finish rolling at a tempera-*Corresponding author: e-mail address: ivo.schindler@vsb.cz ture just above A r3 , since the last deformation at too high temperature can lead to the undesirable growth of the recrystallized grains even before the austenite decomposition begins. Therefore, it is important to provide the most accurate prediction of the A r3 temperature, which, apart from the chemical composition of the steel, is also influenced by the cooling rate, previous deformation and austenitic grain size [4,5]. All additive elements in steel, except silicon, cobalt, and aluminum, increase the stability of austenite and reduce the transformation temperatures A r3 and A r1 ( • C).…”