激光粉末沉积中碳高强贝氏体钢组织与性能研究

Microstructure and properties of medium-carbon high strength bainite steel fabricated by laser powder deposition

为了实现高强贝氏体钢零部件增材修复的目的,采用激光粉末沉积+等温热处理的方法制备了一种中碳高强贝氏体钢,其合金成分(质量分数)为Fe-0.0029C-0.0150Si-0.0150Mn-0.0096Cr-0.0120Ni-0.0100Al-0.0050Mo。使用扫描电子显微镜、X射线衍射仪对贝氏体钢的微观组织进行表征,采用拉伸试验机以及显微维氏硬度仪对材料的力学性能进行表征,试样沉积后在280℃盐浴等温处理5h具备最佳综合性能,平均显微硬度达到494.5HV,抗拉强度达到1248MPa、屈服强度达到1037MPa,延伸率达到14.5%。结果表明,不同工艺参量试样微观组织均由贝氏体板条以及残余奥氏体组成,且组织均匀,无碳化物、偏析以及气孔夹杂等缺陷,但等温时间过低以及等温温度过高都会导致组织性能劣化。该研究为高强零部件的增材修复提供了参考。

In order to realize the additive preparation and surface repair of high strength bainitic steel parts,amedium-carbon high strength bainite steel was prepared by laser powder deposition and salt bath isothermal treatment with different process parameters.The alloy composition(mass fraction)was Fe-0.0029C-0.0150Si-0.0150Mn-0.0096Cr-0.0120Ni-0.0100Al-0.0050Mo.The microstructure of the steel wascharacterized by scanning electron microscope and X-ray diffraction,and the mechanical properties of steel were tested through tensile testing machine and Vicker’s microhardness tester.The effect of isothermal temperature and isothermal time on microstructure and properties of the steel during salt bath isothermal process was analyzed.The best integrated mechanical properties were observed after deposition and salt bath isothermal at 280℃for 5h,the average microhardness,tensile strength,yield strength,andelongationwas 494.5HV,1248MPa,1037MPa,and 14.5%,respectively.The results showe that the microstructure of the samples with different process parameters is composed of lath-like bainite and retained austenite,and the microstructure is uniform without defects such as carbide,segregation,pore and inclusion,but too low isothermal time or too high isothermal temperature would lead to the deterioration of the microstructure.This study provides a reference for the additive and repair of high strength parts.