Research on Application Technology of M50NIL Steel for Aviation~*-Engine Spindle Bearing

寇思源

古乐

硕士

哈尔滨工业大学

M50NiL钢;;引导面;;磨损;;TiN薄膜;;渗氮

航空发动机主轴轴承使用工况特点主要为高温、高载荷和高速。轴承在配合产生的拉应力和高速旋转下套圈及滚动体产生的高离心力作用下,轴承套圈将产生周向拉应力,当工作表面周向拉应力过大时容易导致表面疲劳,从而使采用韧性较差材料的轴承套圈出现疲劳断裂,随着航空发动机的升级换代轴承结构从标准化过渡为弹支轴承一体化结构,要求材料变形延展能力较高。综合以上情况,四代机以后发动机主轴轴承材料中由M50NiL钢逐渐替代M50钢,此钢种虽相对具有更好的延展性和耐疲劳性,但在型号应用中出现了多起引导面磨损问题,表明此材料的成熟应用仍存在非常大的薄弱环节,因此本文主要从M50NiL钢基础性能、耐磨性和表面改性等方面开展研究,掌握材料性能、弥补材料薄弱点、进一步挖掘材料性能,从而使M50NiL钢尽快成熟应用于航空发动机轴承中。本文主要围绕以下三方面开展研究:通过对M50NiL钢材料本身物理特性和化学特性进行全面分析,并与M50钢进行全面性能指标对比,结合该两种钢材轴承的应用情况,找出M50NiL钢的优点和缺点。优点主要为具有长寿命、结构复杂、耐高温和高dn值的特点,缺点为该材料作为引导存在表面不耐磨损的问题。针对M50NiL钢引导面易磨损的缺点,从机理上分析此材料不耐磨的原因,从内部结构设计、表面涂层和表面强化等方面开展论证,结合国外相关资料的查阅制定解决措施,并通过初步试验验证措施的有效性,表面涂覆TiN薄膜可以避免磨损。通过对渗氮工艺技术进行研究,确定最佳的制备工艺路线,并完成试样加工,经过与国外试样进行硬度、应力梯度对比,确定国产M50NiL钢二次硬化技术的优缺点,从而不断完善、提高,最终实现M50NiL钢各项应用指标与国外相当的目标。

The main operating conditions of aeroengine spindle bearings are high temperature high load and high speed.Bearing ring will produce the circumferential tensile stress under the action of the circumferential stress produced by the fitting and the high centrifugal force produced by the ring and the rolling body under the high speed rotation.It is easy to cause the surface fatigue when the circumferential tensile stress of the working surface is too large,therefore the bearing rings with poor toughness materials will appear fatigue fracture.At the same time,with the development of aeroengine bearing,the bearing structure has changed from standardization to integration of elastically supported bearing,and it requires high deformation and extension ability of materials.According to the above situation,the aeroengine spindle bearing material gradually replaced M50 steel by M50 NiL steel after fourth-generation fighter jets.Although M50 NiL steel has better ductility fatigue resistance,there are many wear problems of guide surface in the model application.It indicates that there are still very large weaknesses in the mature application of this material.Therefore,it is necessary to study the basic properties,non wear resistance and surface modification of M50 NiL steel.By making up for the material defects,mastering and further excavating the material properties,the M50 NiL steel can be used in aeroengine bearings as soon as possible.This mainly focuses on the following three aspects.Through a comprehensive analysis of the physical and chemical properties of the M50 NiL steel material and a comparison of the overall performance of the M50 steel,the advantages and disadvantages of the M50 NiL steel are found through the application of the two kinds of bearings.The advantages are characterized by long life,complex structure,high temperature resistance and high dn value.The disadvantage is that the material carries a risk of surface wear as a guide surface.In view of the shortcomings of the easy wear of the guide surface of the M50 NiL steel,the reason why the material is not wearable is analyzed from the mechanism,analysis are carried out from the aspects of internal structure design,surface coating,and surface strengthening.The solution measures are formulated in combination with the access to the relevant foreign data.The effectiveness of the measure is confirmed by the preliminary test,surface can be coated with TiN film to avoid wear.Through the study of the nitriding technology,the optimal preparation process route is determined,and the sample processing is completed.The advantages anddisadvantages of the secondary hardening technology of the domestic M50 NiL steel are verified by compared the hardness and stress gradients with foreign samples,and the performance of the M50 NiL steel is constantly improved.Finally,the goal of equivalent of the application indicators of the M50 NiL steel and foreign is achieved.