Effect of Zr addition on toughness in the simulated heat-affected zone of high-titanium low-alloy steels

ABSTRACT The effect of Zr addition on the impact energy at −20°C, the microstructure, and inclusions of high-titanium low-alloy steels in the simulated heat-affected zone was investigated. The impact energy of the steel without Zr addition was 25.7 J and increased to 242.9 J for the steel with the addition of 80 ppm Zr. When the heat input was 300 kJ cm−1, the impact energy of the steel without Zr addition was 17.5 J and increased to 140.9 J for the steel with 80 ppm Zr, the nucleation potential of AFs increased from 24.4 /mm2 to 76.7  /mm−2, and the average nucleation potential of inclusions decreased from 2.02 to 1.67. The grain refinement by the formation of acicular ferrites stemmed from the increase of 1–3 μm Al-Ti-Zr-O inclusions was responsible for the toughness improvement in CGHAZ of the Zr-bearing steel.