提高汽车稳定杆用钢60Si2MnA疲劳寿命的工艺实践

Process Practice for Improving Fatigue Life of Steel 60Si2MnA for Auto Stabilizing Rod

采用金相显微镜、扫描电镜和能谱分析仪分析汽车稳定杆用钢60Si2MnA(/%:0.56C,1.74Si,0.74Mn,0.011P,0.007S,0.04Cr)疲劳寿命低的原因主要为表面脱碳层较深,表面存在裂纹,淬火组织中有较多铁素体。通过加0.22%Cr,增加连铸坯全修磨工序,150 mm×150 mm铸坯加热温度由1130~1 150℃降至1 080~1 100℃等工艺措施显著降低了淬火后钢中铁素体含量,钢材表面无裂纹缺陷,φ18 mm棒材总脱碳层深度由原128μm降至87.5μm,使该钢的疲劳寿命由6~10万次提高至20~25万次,满足了设计要求。

The main reason of low fatigue life of steel 60Si2MnA for auto stabilizing rod （/% ： 0. 56C, 1.74Si, 0.74Mn, 0. 011P, 0. 007S, 0. 04Cr） is analyzed by using optical microscope, scanning electron microscope and energy dispersive spectrometer, i.e. the decarburized layer is deeper, there are cracks at surface of steel rod and the quenched structure has a lot of ferrite. With the process measures including adding 0. 22% Cr in steel, adding procedure of grinding on while surface of billet and decreasing heating temperature of 150 mm ~ 150 mm casting billet from original 1 130 ~ 1 150 ℃ to 1 080 ~ 1100℃, the ferrite content in quenched steel decreases obviously, there is no crack defect on surface of steel bar and the total decarburized layer uepth of φ18 mm bar decreases from original 128 μm to 87.5 μm, as a results the fatigue life of the steel increases from 6 ×10^-4 ~ 10 ×10^-4to 20 ×10^-4-25 ×10^-4to meet the requirement of design.