通过建立模型，计算研究了冷却速度对铁素体-珠光体带状组织的影响机制，并通过试验验证了模型计算结果的正确性。结果表明：贫溶质区与富溶质区的Ar3温度差异是产生带状组织的前提条件，碳在贫溶质区产生珠光体之前的扩散距离是带状程度的决定因素。随着冷却速度的增大，贫溶质区与富溶质区的Ar3温度差增大，但碳扩散的距离减小，Ar3温度差对带状组织的影响也减小，带状程度减轻。
In order to analyze the mechanism of effect of cooling rate on ferrite/pearlite banded structure, a quantitative model was developed for SAE8822H gear steel. The calculation results are consistent with that of experiment obtained by electron microprobe analysis and optical microscopy. The results show that the difference of Ar3 temperatures for solute-depleted and solute-rich zones in the matrix is a prerequisite for the band formation, while the diffusion distance of carbon prior to pearlite formation in solute-depleted zone is the determinant of the band intensity. With the increase of cooling rate, difference between Ar3 temperatures increases, but the diffusion distance of carbon decreases, meanwhile the influence of difference between Ar3 temperatures on banded structure decreases, then the banded structure relieved.
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