Influence of continuous annealing soaking temperature on fish-scaling resistance of ultra-low carbon steel for porcelain enameling

Abstract

The relationship between fish-scaling resistance of ultra-low carbon (ULC) enamel steel and continuous annealing soaking temperature was rarely studied before. In this paper, the influence of continuous annealing soaking temperature on microstructure, precipitation behavior and fish-scaling resistance of ULC steel for porcelain enameling was investigated. The results obtained were as follows: for ULC enamel steel, with the continuous annealing soaking temperature increasing from 750 °C to 840 °C, the mean diameter of second phase particle increased from 41 nm to 52 nm, the corresponding volume fraction decreased from 5.8 × 10−3 m3/m3 to 2.9 × 10−3 m3/m3, and the ferrite grain size grew from 13.4 µm up to 17.3 µm, the hydrogen permeation value (TH value) decreased from 32 min/mm2 to 12 min/mm2. The grain boundary and precipitates are main hydrogen traps, as the ferrite grain size increased and the volume fraction of second phase particles decreased, the fish-scaling resistance of ULC enamel steel decreased.