Thermal Behavior of a Rod during Hot Shape Rolling and Its Comparison with a Plate during Flat Rolling

Abstract

The thermal behavior of a rod during the hot shape rolling process was investigated using the off-line hot rolling simulator and numerical simulation. Additionally, it was compared with a plate during the flat rolling process to understand the thermal behavior of the rod during the hot rolling process in more detail. The temperature of the rod and plate during the hot rolling process was measured at several points with thermocouples using the rolling simulator, and then the measured temperature of each region of a workpiece was analyzed with numerical simulation. During hot rolling process, the temperature distribution of the rod was very different from the plate. The temperature deviation of the rod with area was much higher than that of the plate. The variation in effective stress of the rod along the circumferential direction can induce the temperature difference with area of the rod, whereas the plate had a relatively lower temperature deviation with area due to the uniform effective stress on the surface area. The heat generation by plastic deformation during the forming process also increased the temperature deviation of the rod with area, whereas strain distribution of the plate during flat rolling contributed to the uniformity of temperature of the plate with area. The higher temperature deviation of the rod along the circumferential and radial directions during the shape rolling process can increase the possibility of occurrence in surface defects compared to the plate during flat rolling.

Effects of Water Jet Height and End Dipping on the Cooling Rate and Hardenability in the Jominy End Quench Test

“…After drilling a 1 mm-diameter hole to the 12.7 and 1 mm in depth from the surface of the specimen, thermocouples of 1 mm-diameter were embedded to reduce the external thermal disturbance. Hwang [28,29] successfully measured the temperature of the steels under the various cooling rates and process conditions using the above-mentioned method, although temperature measurement using a thermocouple is very sensitive to the cooling conditions and measurement methods. Regarding the uncertainty in temperature measurements, the accuracy of the thermocouple position within the Jominy specimen was determined to be approximately ±0.2 mm, and the standard limit of error in this K-type thermocouple is about 0.75% of the measured temperature within the temperature range of 20 to 950 • C. Temperature data were stored by a data recorder apparatus with a sampling time of 0.2 s. The error of the data recorder device is approximately ±0.05%.…”

Developing a method of accounting for the existence of local surface heat exchange in rods of variable cross-section

“…In [16], the thermal behavior of a bar during the hot rolling process was investigated using an offline hot rolling simulator and numerical simulation. In addition, it was compared with the sheet characteristics during the flat rolling process in order to understand the thermal behavior of the bar during the hot rolling process in more detail.…”

Modeling and Simulation of Steel Rolling with Microstructure Evolution: An Overview

“…Significant temperature variation within a workpiece is available during the rolling process, especially in shape rolling. [ 118 ] Residual stress is induced, causing unintentional shape forms of the final rolled product. [ 119 ] However, during the simulation of plates or rebar rolling processes, the residual stress calculations are often ignored due to the simple shape and high temperature.…”