交变载荷条件下NC30Fe合金微动损伤特性研究

Fretting Damage Behavior of NC30Fe Nickel- Based Alloy under Alternating Load Conditions

针对NC30Fe镍基合金管与1Cr13不锈钢圆柱配副件,采用'十'字交叉接触方式,在改进的PLINT微动试验机上进行交变载荷条件下微动磨损试验.试验环境温度为25℃(air)、300℃(air)和300℃(N2);切向位移幅值为100~200μm,切向微动频率为2 Hz;法向载荷为20和50 N,法向激振频率为10和50 Hz.结果表明:在法向激振力叠加作用下,NC30Fe镍基合金Mises等效应力幅值较静载荷时大,疲劳累积损伤严重,微裂纹更易萌生并扩展.微动疲劳剥落成为磨损中后期主要损伤形式,清洗后磨痕表面形貌呈现大量剥落坑.第三体层形成后具有承载、传递和吸收激振能量作用,三种环境下,第三体层厚度和氧化程度不同,对疲劳剥落作用结果影响较大.

The fretting wear behavior of NC30 Fe nickel- base alloy tube in contact with crossed 1Cr13 cylinderical sample has been investigated on the improved PLINT fretting rig under alternating load conditions. Different experimental conditions have been taken into consideration( i. e. environmental temperature at 25 ℃( air),300 ℃( air) and 300 ℃( nitrogen),normal loads at 20 N and 50 N,tangential displacement amplitudes range from 100 μm to 200 μm,tangential fretting frequency at 2 Hz,excitation frequencies at 10 Hz and 50 Hz). Results show that the amplitudes of Mises stress for NC30 Fe nickel- base alloy under the additive effect of normal exciting forces were greater than that under static loads.Consequently,the fatigue cumulative damage were obvious to be characterized and the micro- crack initiation and propagation were easier to emerge,all those led the material to peel off a lot. After cleaning,a lot of flaking pits were showed up on the worn surface according to surface morphological analysis. Fretting fatigue delamination became the main wear damage mechanism in the middle and late period of fretting wear. As the third- layer could bear,transmit and absorb the excitation energy,different layer thicknesses and degrees of oxidation can make a big difference to the results of fatigue delamination under each of the test conditions.