Ensuring complete scale removal from wire rod before drawing

Abstract

Low-temperature coiling in the Stelmor line (∼850°C) is best for chemical scale removal. In that case, thin, dense scale is formed, without peeling, spots, or blisters. For low-carbon wire rod, the plasticity declines monotonically, while the strength increases. For high-carbon wire rod, the microstructure is unsatisfactory: tempering sorbite and also bainite and pearlite of reduced dispersity. (The optimum scale consists of wustite.) With increase in coiling temperature (950–1000°C), mechanical scale removal is best, on account of the difference in thermal expansion of the scale and the metal. In storage and prolonged transportation, blisters and scale-free sections may lead to corrosion and, on etching, to overetching of the metal.