退火条件对取向硅钢脱碳效果的影响

Effects of annealing condition on decarburization of grain oriented silicon

通过对取向硅钢脱碳退火的实验研究,比较退火气氛、退火温度和退火时间对取向硅钢脱碳效果的影响。结果表明,在退火温度830℃、保护气氛氢浓度为25%条件下退火3 min,保护气氛露点为40.0、42.5、45.0和47.5℃时,试样碳含量分别为33.2×10-6、26.7×10-6、6.3×10-6和62.8×10-6。在退火温度830℃、保护气氛露点为45℃的条件下退火3 min,保护气氛氢气浓度为10%、25%、40%和55%时,试样碳含量分别为298.0×10-6、6.3×10-6、30.0×10-6和26.5×10-6。在保护气氛露点为45℃、氢气浓度25%的条件下退火2.5 min,退火温度为790、810、830、850和870℃时,试样碳含量分别为195.0×10-6、126.0×10-6、10.1×10-6、52.0×10-6和26.0×10-6。在退火温度830℃、保护气氛氢浓度为25%、保护气氛露点为45℃的条件下,脱碳效果最好。脱碳退火时,试样表面生成的氧化物影响H2O、H2和CO等在炉内气氛和脱碳反应界面间的扩散,这是导致试样碳含量随水氢分压比呈"U"型分布的主要原因。退火温度升高,一方面导致试样再结晶速度增快,基体内位错密度下降加快;另一方面导致碳沿晶内和位错扩散系数增大。这是导致试样碳含量随温度呈反"N"型分布的主要原因。

Effeets of annealing atmosphere, temperature and time on decarburization of grain oriented silicon steel were investigated by the decarburization annealing experiment. The results show that when the annealing temperature is 830 ℃, and the H2 concentration in protective atmosphere is 25% , and the annealing time is 3 min, and the dew points of the protective atmosphere are 40. 0, 40. 0, 42.5, 45.0 and 47. 5 ℃ , the carbon content of the annealed specimens are 33.2 × 10^-6,26.7 ×10^-6,6.3 ×10^-6 and 62. 8 × 10^-6, respectively. When the annealing temperature is 830 ℃ , and the dew point is 45 ℃ , and the annealing time is 3 min, and the H2 concentration are 10% , 25% , 40% and 55% , the carbon content of the annealed specimens are 298.0 ×10^-6, 6.3× 10^-6, 30. 0 ×10^-6 and 26.5× 10^-6, respectively. When the dew point is 45 ℃ , and the H2 concentration is 25% , and the annealing time is 2.5 min, the annealing temperature are 790, 810, 830, 850 and 870 ℃ , the carbon content of the annealed specimens are 195.0 × 10^-6, 126. 0× 10^-6, 52. 0 × 10^-6 and 26. 0× 10^-6, respectively. When the annealing temperature is 830 ℃ , and the dew point is 45 ℃ , and H2 concentration is 25% , the decarburization effect of the specimens is the most optimized. When the decarburization occurs, the oxides on the surface of the specimen may affect the diffusion of H20, HE and CO at the interface between atmosphere and steel, which is the main reason for a ＂U＂ distribution of carbon content in the specimen under the atmosphere with different pH2O/Pn2 ratio. Increasing annealing temperature may increase the intergranular diffusion coefficient of carbon and the diffusion of dislocation, and reduce the dislocation density in the matrix, which may be the main reason for an inverse ＂N distribution of carbon in the sample with increasing the annealing temperature.