In order to optimize composition and hot-rolling cooling process of 82B to improve strength of 82B wire rod

the influence of isothermal transformation temperature of steel 80 and steel 82B on phase transformation time and pearlite interlamellar spacing and the influence of Cr content on phase transformation temperature are tested

and the influence of Cr- alloying and phase transformation control on microstructure and tensile strength of 82B wire rod is analyzed. The phase transformation speed of 82B is the most fast at 595 -615 °C

with transformation time for 10 〜15 s

and an idea pearlite interlamellar spacing o£ 0. 10 ~0. 20 μm is gotten at 590 ~625 °C. The temperature scope and transformation speed of phase transformation of steel 82B could be controlled by adding 0.18% _0. 24% Cr and controlling hot-rolling cooling speed so as to obtain pearlite microstructure with uniform thin interlamellar spacing. The main components of Φ12.5 mm steel 82B wire rod are modified to 0.78% ~0.84 %C

0.15% ~0.35 % Si

0.78% ~0.88 % Mn and 0. 18% ~0.24 % Cr. In hot- rolling cooling process

with weakened water cooling

strengthened forced air cooling

laying temperature of 82B wire rod at 840 ~ 880 °C(aiming at 860 °C )

and increasing forced air cooling speed of 82B wire rod

the strength of the wire rod is improved.