Effect of Austenitization Temperature on Hot Ductility of C-Mn-Al HSLA Steel.

Peter Prislupcak,Peter Zimovcak,Pavol Zahumensky,Ivo Demjan,Lubos Juhar,Jana Bidulska,Roman Gburik,Tibor Kvackaj,Pavol Zubko,Viera Homolova

doi:10.3390/ma15030922

Abstract

The article aims to investigate the effect of different austenitization temperatures on the hot ductility of C-Mn-Al High-Strength Low-Alloy (HSLA) steel. The thermo-mechanical simulator of physical processes Gleeble 1500D was used for steel hot ductility study. Hot ductility was estimated by measuring the reduction of area after static tensile testing carried out at temperatures in the range 600 °C to 1200 °C with the step of 50 °C. Evaluation of fracture surfaces after austenitization at 1250 °C and 1350 °C with a holding time of the 30 s showed significant differences in the character of the fracture as well as in the ductility. The fracture surfaces and the microstructure near the fracture surfaces of samples at a test temperature of 1000 °C for both austenitization temperatures were analyzed by Scanning Electron Microscopy (SEM), Light Optical Microscopy (LOM), and AZtec Feature analysis (particle analysis of SEM). AlN and AlN-MnS precipitates at grain boundaries detected by the detailed metallographic analysis were identified as the main causes of plasticity trough in the evaluated steel. Moreover, using Thermo-Calc software, it was found that AlN particles precipitate from solid solution below the temperature of 1425 °C.

Highlights

The techniques of continuous casting and direct rolling have been introduced and extended in order to increase process efficiency by saving on energy consumption, human labor, and production equipment
Cracks are known to form in three distinct temperature ranges that depend on the ductility of steel: so-called high-temperature zone 1340 ◦C to solidus, intermediate-temperature range 800 ◦C to 1200 ◦C, and so-called low-temperature zone 700 ◦C to 900 ◦C [7]
Loss of ductility in the intermediate-temperature zone is strongly dependent on the Mn/S ratio and the particular thermal history of the steel [7,8]

Summary

Introduction

The techniques of continuous casting and direct rolling have been introduced and extended in order to increase process efficiency by saving on energy consumption, human labor, and production equipment. Based on the chemical compoMaterials 2022, 15, s9i2t2ion of results, it can be assumed that the particles of the second phase found at grain boundaries were coarse AlN-MnS precipitates. The fracture was brittle and intergranular with low energy to break, caused probably by coarsening the former austenite grain and second-phase particles precipitating at grain boundaries.

Results

Conclusion