Hot Ductility of a Microalloyed Steel in the Intermediate Temperature Range

Abstract

In this study hot ductility has been determined from tensile tests for two states of a microalloyed steel: after casting and after rolling processes. Hot deformations were carried out at speeds varying from IO-~S-' to 10-~s-l and temperatures from 750°C to 110O0C. Two heat treatments were chosen before hot deformation. A ferrite precipitation is observed at austenitic grain boundaries in the intercritical temperature range, causing intergranular embrittlement. Ductility trough is deeper in the as-cast samples due to the growth of large grain size. Also, precipitation makes the hot ductility curve wider and deeper around 900°C. The results show a decrease in hot ductility. Minimum values of hot ductility are determined for (ITC) treatment at 9W°C and for (DTC) treatment at 800°C. For this second treatment another decrease in hot ductility was observed at 900°C. We can explain hot ductility losses by the presence of precipitates in the austenitic region and the presence of the two-phase structure in the intercritical region.

The effect of ductility minimum temperature in CuNi25 alloy

“…In professional literature effect of ductility minimum temperature is widely described [1][2][3][4][5][6][7], the scientific research shows that this effect is a common attribute of many polycrystal metals and alloys [8,9] for example copper and its alloys [10][11][12], steel [13][14][15], occasionally this phenomena has not been noticed [16,17].…”

Comparing the Hot Ductility Behaviour of Low‐Carbon Microalloyed Nb‐V‐Ti Steels During Two Thermal Cycling Routes: Solutionizing and Precipitation Treatments

“…To simulate the straightening operation experienced by the products during hot drawing of heavy plates (HR material), and conventional continuous casting (CS material), two groups of tensile specimens were subjected to two respective kinds of thermal schedules, as shown in Figure . For this purpose, cylindrical tensile specimens of 17 mm in gauge length and 6 mm in diameter were machined from the as hot rolled plate (HR) and cast product (CS) with their longitudinal axis parallel to their main rolling direction.…”

“…To date, this research area has tended to focus on continuous casting and too little attention has been paid to hot drawing of heavy plates, as the two processes involve common issues, particularly those related to surface cracking during straightening operation at high temperature. Therefore, the major goal of the present study aims to provide an updated account to gain a better understanding by comparing the hot ductility behavior of commercial low‐carbon V‐Nb‐Ti steel with two different initial microstructures, when subjected to two separate thermal cycles, namely solutionizing during reheating and precipitation during cooling.…”