Investigation of cooling parameters effects on product properties in building profiles

Fast production processes and products with high added value are preferred in medium-sized rolling mills. Therefore, it is of great importance to produce building profiles for these enterprises. On the other hand, building profiles are exposed to many internal and external factors due to their place of use. In hot rolled structure profiles, quenching process is preferred and thus, production capacity is increased by making a faster production. The quenching process can be carried out at different production points and with different techniques. Through these techniques, profile microstructures and end product properties can be improved. In this study, it is aimed to contribute to end product properties by changing the quenching status. Today, the use of building profiles stands out in many areas. These fields of application cover many fields such as energy, ship, mine, bridge, automotive. In the literature and practice, the microstructure and mechanical properties of the material obtained as a result of the hot rolling process vary according to the field of use of steel, but have a very important place. The expected mechanical properties of the material and the desired microstructure are achieved by cooling the steel to a large extent. In this study, a cooling practice which improves the material properties is proposed in contrast to the cooling condition in conventional rolling. When the cooling conditions in conventional rolling are examined, it is seen that the steel is a process step for cooling only. The cooling state is not a process step, but rather a process mechanism that incorporates innovative information that improves the process. A general cooling system consists of a quench zone and a cooling water supply circuit. In this study, after determining the main cooling parameters (water pressure, nozzle-sample distance and position of angled nozzles) in the gusset manufacturing process produced from low alloy structural steels, corrosion behavior, mechanical and microstructural changes of the quenching process were investigated. In this study carried out in the rolling mill of Kardemir Haddecilik Sanayi ve Ticaret A.Ş., a 50x50x5 mm gusset sample without water, 50x50x5 mm gusset sample with direct quenching and a rolling speed of 13 m / sec , the rolling output temperature of 950 ℃ ve and 48 m the properties of 50x50x5 mm S275JR quality angle specimens cooled by 3.58 sec in each of the five combs were compared with the JBU-1/4 '' - 90 ° nozzles in the cooling zone with a water temperature of 10 ℃ ve at a distance of 350 mm ve and a water pressure of 1.2 bar. After the cooling practice, mechanical properties of each sample were measured. Microstructure investigations were performed with optical microscope and Scanning Electron Microscopy (SEM).The final phase structure of the material was analyzed by X-ray diffraction (XRD) method. Corrosion behavior of the samples was analyzed by salt test. By evaluating the obtained data, the optimum point of the aqueous cooling required for the process was determined by the cooling practice used in this study.. The most accurate cooling type for the material is aimed to be brought closer to the cooling properties in its own ambient conditions and the situations that may occur under the conditions of continuous water supply are compared. A small increase in the mechanical values of the material was observed as a result of the cooling application. Although there is an increase in hardness value and a decrease in toughness, these values show significant advantages over continuous cooling. This has led to better straightening of the final product, the other process step, and to achieve value-added products within the standard without any slowdown in production speed.