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W-200型无阀冲击器活塞,大部分寿命在3000～4000米之间,最高达7000米,冲击次数达76×10~6。但有的活塞寿命低至几十米,只有正常使用寿命的1/5～1/100,而活塞小头应力只有疲劳极限的1/4～1/7,冲击次数也不高就坏了,这是为什么?本文就此问题,根据断裂活塞的断口特征和金相组织,并应用断裂力学的观点分析了活塞早期失效的原因,还提出了提高其使用寿命的途径。
W-200 valveless impactor piston, most of the life of 3000 to 4000 meters, up to 7000 meters, the impact of number of 76 × 10 ~ 6. But some piston life as low as tens of meters, only the normal life of 1/5 ~ 1/100, while the piston head stress fatigue limit of only 1/4 ~ 1/7, the impact is not high on the number of broken, This is why? In this paper, based on the broken piston fracture characteristics and microstructure, and fracture mechanics point of view of the reasons for the early failure of the piston, but also put forward ways to improve its service life.