Grain Size Evolution and Mechanical Properties of Nb, V–Nb, and Ti–Nb Boron Type S1100QL Steels

Titanium additions are often used for boron factor and primary austenite grain size control in high- ultra-high-strength alloys. Due to the risk of formation coarse TiN during solidification addition titanium is limited respect nitrogen. The nitrides working as non-metallic inclusions formed last front can degrade fatigue properties weldability final product. In presented study three microalloying systems with minor were tested, two without any addition, evaluate evolution mechanical pre-defined as-cast, hot forging, rolling, off-line heat-treatment strategy meet demands S1100QL steel. Microstructure from hot-forged martensitic microstructure was observed, continuous cooling transformation diagrams non-deformed constructed heat treatment, Nb V–Nb compared Ti–Nb system a addition. Using parameters laboratory environment all micro-alloying provide needed properties, especially be successfully replaced having highest response tensile still obtaining satisfying toughness 27 J at –40 °C using Charpy V-notch samples.