82B钢的微合金化-相变控制与生产实践

Micro-Alloying and Phase Transformation Control of Steel 82B and Production Practice

为了优化82B钢的成分和热轧冷却工艺,以提高82B盘条的强度,测定了80钢和82B钢的等温转变温度对相变时间、珠光体片层间距的影响以及Cr元素对82B相变温度的影响,分析了Cr合金化和相变控制对82B盘条的微观组织和抗拉强度的影响。对于82B,当温度在595~615℃相变速度最快,其转变时间为10~15 s,在590~625℃可得到理想的0.10~0.20μm的珠光体片层间距;通过添加0.18%~0.24%Cr和控制热轧冷却速度,可以控制82B钢的相变温度区间和相变速度,得到均匀细片状的珠光体组织;将Φ12.5 mm 82B盘条的主要成分调整为0.78%~0.84%C、0.15%~0.35%Si、0.78%~0.88%Mn和0.18%~0.24%Cr;在热轧控冷过程中,弱化水冷,强化风冷,控制82B盘条的吐丝温度为840~880℃,目标值860℃,增大82B盘条在风冷线上的冷速,提高了盘条的强度。

In order to optimize composition and hot-rolling cooling process of 82 B to improve strength of 82 B wire rod,the influence of isothermal transformation temperature of steel 80 and steel 82 B on phase transformation time and pearlite interlamellar spacing and the influence of Cr content on phase transformation temperature are tested,and the influence of Cralloying and phase transformation control on microstructure and tensile strength of 82 B wire rod is analyzed.The phase transformation speed of 82 B is the most fast at 595~615℃with transformation time for 10~15 s,and an idea pearlite interlamellar spacing of 0.10~0.20 μm is gotten at 590~625℃.The temperature scope and transformation speed of phase transformation of steel 82 B 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 82 B 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 hotrolling cooling process,with weakened water cooling,strengthened forced air cooling,laying temperature of 82 B wire rod at840~880℃(aiming at 860℃),and increasing forced air cooling speed of 82 B wire rod,the strength of the wire rod is improved.