加热、轧制、缓冷工艺对60Si2Mn弹簧钢脱碳特性的影响

Influence of heating,rolling and slow cooling processes on decarbonization characteristics of 60Si2Mn spring steel

60Si2Mn弹簧钢的脱碳特性与加热、轧制、缓冷工艺紧密相关,通过金相法分析测量60Si2Mn弹簧钢在加热温度为1000~1250℃、加热时间为60~300 min、上冷床温度为700~900℃、缓冷速率为0.5~3.0℃·s^(-1)的工艺条件下的脱碳层深度,并结合硬度分析得到了最佳工艺路线。同时,建立了部分脱碳层深度与加热时间的计算模型。结果表明:部分脱碳层深度随着均热段加热时间的增加而增加,当均热段加热时间为60 min时,部分脱碳层深度在1150℃时出现极大值,为48.1μm;当均热段加热时间>75 min时,加热温度为1200和1250℃时的部分脱碳层深度均大于加热温度≤1150℃时。部分脱碳层深度随着上冷床温度的降低而降低,缓冷速率对脱碳的影响较小,但随着缓冷速率降低基体热轧布氏硬度降低。得出的最佳工艺为:均热段加热时间为60 min、加热温度为1050℃、上冷床温度为700℃、缓冷速率为0.5℃·s^(-1),此时基体组织为铁素体和珠光体,部分脱碳层深度为26μm,硬度为281 HBW。研究结果有助于提高60Si2Mn弹簧钢的生产效率及生产质量。

The decarburization characteristics of 60Si2Mn spring steel are closely related to heating,rolling and slow cooling processes.Therefore,the depth of decarburization layer for 60Si2Mn spring steel in the condition of the heating temperature of 1000-1250 ℃,the heating time of 60-300 min,the upper cooling bed temperature of 700-900℃,and the slow cooling rate of 0.5-3.0℃·s^(-1) was measured by metallographic analysis,and combined with the hardness analysis,the optimal process route was obtained.At the same time,a calculation model was established for the depth of partial decarburization layer and the heating time.The results show that the depth of partial decarburization layer increases with the increasing of heating time in the soaking section.When the heating time in the soaking section is 60 min,the depth of partial decarburization layer reaches a maximum of 48.1 μm at 1150 ℃.When the soaking time is greater than 75 min,the depth of partial decarburization layer at 1200 and 1250 ℃ is greater than that at the heating temperature≤1150 ℃.However,the depth of partial decarburization layer decreases with the decreasing of upper cooling bed temperature,the influence of slow cooling rate on decarburization is relatively small,and the Brinell hardness of matrix decreases with the decreasing of slow cooling rate during hot rolling.The optimal process is the heating time of 60 min in the soaking section,the heating temperature of 1050 ℃,the upper cooling bed temperature of 700 ℃,and the slow cooling rate of 0.5 ℃·s^(-1).At this time,the matrix structure is ferrite and pearlite,the depth of partial decarburization layer is 26 μm,and the hardness is 281 HBW.Thus,the research results contribute to improving the production efficiency and quality of 60Si2Mn spring steel.