TD盐浴法制备LD钢碳化钒覆层及其摩擦磨损性能研究
发布时间：2018-09-05 16:01
【摘要】：LD钢是一种新型的冷作模具钢,已广泛应用于模具制造业。但是模具钢常处于高应力、高冲击力作用下易被磨损,模具使用寿命不高,对其进行表面强化可以有效提高表面硬度和耐磨性。在众多表面强化方法中TD盐浴法具有设备简单、强化效果好等优点,故TD法已成为提高模具耐磨性的有效途径。本文通过对LD冷作模具钢进行TD盐浴法制备碳化钒涂层,探究了渗钒工艺对渗钒层组织、物相及性能的影响,并探讨渗钒层形成机制;研究不同磨损试验条件下渗钒层的摩擦磨损行为和磨损机制。同时研究稀土添加量对渗钒层组织和性能的影响。研究结果表明:盐浴最佳基础配方为:78 Na2B4O7+8 V2O5+4 Al+10 NaF,wt.%;不同温度、时间工艺下制备得到的渗钒层物相均为VCx相,覆层厚度和显微硬度随渗钒温度的升高而增加,覆层厚度和显微硬度值随TD盐浴渗钒处理时间增长而增加。LD钢最佳渗钒工艺为950℃×8 h,该工艺下得到的渗钒层厚度约为6.1μm,显微硬度值约为1975 HV,约为原始试样显微硬度值的2.63倍。950℃时渗层的生长动力学曲线满足类抛物线形方程l2.632=13.657t,形成的碳化钒晶粒为等轴晶粒。随着载荷和滑动速度的增加,渗钒试样和原始试样的摩擦系数均逐渐降低,在8.2 N载荷下,渗钒后试样的磨损体积约为原始试样磨损体积的1/10~1/9。在不同滑动速度条件下,渗钒试样的体积磨损量均约为原始试样体积磨损量的1/8~1/7,故LD钢经TD盐浴渗钒处理后,耐磨性得到了有效提高。渗钒层磨损机制主要为疲劳磨损和粘着磨损。950℃×8 h TD盐浴稀土渗钒工艺中稀土最佳添加量为4%,其渗层厚度和硬度分别为7.5μm和2235 HV,与普通渗钒相比,分别提高了29.3%和22.8%。此外,添加4%稀土后渗层表面晶粒尺寸约为0.32μm,未添加稀土渗钒层表面晶粒尺寸约为0.57μm,故添加稀土后具有明显的细化晶粒作用。
[Abstract]:LD steel is a new type of cold working die steel, which has been widely used in die manufacturing industry. However, die steel is often subjected to high stress and wear under high impact force, and the service life of die is not long. Surface strengthening can effectively improve the surface hardness and wear resistance. Among many surface strengthening methods, TD salt bath method has the advantages of simple equipment and good strengthening effect, so TD method has become an effective way to improve the wear resistance of dies. In this paper, vanadium carbide coating was prepared by TD salt bath method on LD cold working die steel. The effect of vanadizing process on the microstructure, phase and properties of vanadizing layer was investigated, and the formation mechanism of vanadizing layer was discussed. The friction and wear behavior and wear mechanism of vanadium layer under different wear test conditions were studied. At the same time, the effect of rare earth addition on the microstructure and properties of vanadium layer was studied. The results showed that the optimum basic formula of salt bath was: 1: 78 Na2B4O7 8 V2O5 4 Al 10 NaF,wt.%; at different temperatures, and the vanadium layer prepared by the reaction of different time was VCx phase, and the thickness and microhardness of the coating increased with the increase of vanadium temperature. The coating thickness and microhardness value increase with the increase of TD salt bath vanadizing treatment time. The optimum vanadizing process for LD steel is 950 鈩，
本文编号：2224764
[Abstract]:LD steel is a new type of cold working die steel, which has been widely used in die manufacturing industry. However, die steel is often subjected to high stress and wear under high impact force, and the service life of die is not long. Surface strengthening can effectively improve the surface hardness and wear resistance. Among many surface strengthening methods, TD salt bath method has the advantages of simple equipment and good strengthening effect, so TD method has become an effective way to improve the wear resistance of dies. In this paper, vanadium carbide coating was prepared by TD salt bath method on LD cold working die steel. The effect of vanadizing process on the microstructure, phase and properties of vanadizing layer was investigated, and the formation mechanism of vanadizing layer was discussed. The friction and wear behavior and wear mechanism of vanadium layer under different wear test conditions were studied. At the same time, the effect of rare earth addition on the microstructure and properties of vanadium layer was studied. The results showed that the optimum basic formula of salt bath was: 1: 78 Na2B4O7 8 V2O5 4 Al 10 NaF,wt.%; at different temperatures, and the vanadium layer prepared by the reaction of different time was VCx phase, and the thickness and microhardness of the coating increased with the increase of vanadium temperature. The coating thickness and microhardness value increase with the increase of TD salt bath vanadizing treatment time. The optimum vanadizing process for LD steel is 950 鈩，
本文编号：2224764
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