精控热处理制备45钢表面铁素体层及其性能

Preparation and Properties of Ferrite Layer on Surface of 45 Steel by Refined Controlled Heat Treatment

近年有学者提出了新的热处理技术,即“精确控制降温速率热处理”。采用该新技术处理的低碳钢可获得表面与心部不同的梯度材料,从而具有较高的强度、良好的折弯性能和耐蚀性。采用上述精控热处理在45钢表面成功地制备了单相铁素体层。根据铁碳相图,探讨了45钢表面铁素体层的形成机制,即在降温梯度下较低温的表面先形成铁素体层,并将多余的碳推向较高温的奥氏体心部。采用电子探针显微分析仪测量了45钢表面至心部的碳浓度分布,其结果也证实了上述机制。电化学测试结果表明,表面铁素体层显著改善了45钢的耐蚀性。

In recent years,a new heat treatment has been proposed,that is,“refined controlled cooling rate heat treatment”.The low carbon steel prepared by this new heat treatment can obtain gradient materials with different surface and core,so it has high strength,good bending performance and corrosion resistance.The above refined controlled heat treatment was carried out on the 45 steel,and the single-phase ferrite layer was successfully prepared on the surface of the steel.From the analysis of the iron-carbon phase diagram,the formation mechanism of the ferrite layer on the surface of 45 steel was concluded that,the ferrite layer was first formed on the lower temperature surface under gradient cooling condition,and the excess carbon was discharged to the higher temperature austenite core.The carbon concentration distribution from the surface to the core of 45 steel was measured by electron probe microanalyzer,the results also confirmed the above mechanism.The electrochemical test results showed that the ferrite layer on the surface of 45 steel significantly improved its corrosion resistance.