To obtain a homogeneous pearlitic microstructure in coil‑rolled product made of ShKh15 steel, a continuous heat‑treatment regime with two‑stage cooling was developed on the Stelmor line of a 370/150 wire‑rod mill. Wire rod 5.5–18.5 mm in diameter, after homogenizing annealing of NLZ with a cross‑section of 250 × 300 mm, was investigated. The initial cooling temperature in the coil‑former zone was taken as 870 ± 20°C. Thereafter the rod was cooled on the Stelmor roller conveyor with subsequent holding under thermally insulating covers. The developed regime guarantees diffusional transformation of austenite and produces a ferrite–cementite mixture of sorbitic pearlite with minor (less than 5%) areas of fine‑ and medium‑lamellar pearlite. Subsequent spheroidizing annealing of the rod meets the requirements of State standard GOST 801–2022 with respect to microstructure quality indicators and mechanical properties.
С. А. Савченко (Mon,) studied this question.