دانلود رایگان مقاله تاثیر موقعیت شکاف در آسیب خزش برای لحیم کردن مشترک

Abstract

In this paper, we investigated the effect of notch position on creep damage for Hastelloy C276-BNi2 brazed joint. Three different types of notches locate in edge of base metal (base notch), edge of filler metal (surface notch) and center of filler metal (inside notch) were compared, and the influence of notch geometric parameters on creep damage was also investigated. The results show that the different notch position and dimension generate different creep damage distributions and have a great influence on creep life. The creep failure is the easiest to occur in surface notch, then the base notch, and the last is inside notch. The brazed joint with higher maximum principal stress and von Mises stress generates creep failure easier. For the base notch, the failure time increases with the increase of base notch distance and the creep failure location moves gradually from the center of filler metal to notch tip. The notch locating away from filler metal is beneficial to reduce the creep damage in filler metal and enhance the creep life. For the inside notch, the failure time decreases with notch length increases and the maximum creep damage locates at notch tip. With the increase of inside notch width, the failure time increases first and then keep steadiness, and the failure location moves away from notch tip. The effects of notch position and dimension should be fully considered in creep failure analyses and life assessments of brazed joints

4. Conclusions

This paper studies the effects of notch position on creep damage of brazed joint by continuum creep damage theory and ductility exhaustion damage model. The effects of notch dimension were also investigated. The main results obtained are as follows: (1) Different notch position generates different creep damage distribution and creep failure time. The creep failure most likely happens for a surface notch, and the next is base notch. The inside notch is not easy to generate creep failure. (2) The base notch location has a great influence on the creep damage distribution. If the base notch distance is smaller than the specimen radius, the maximum creep damage locates at the center of filler metal and the failure time increases as the notch distance increases. Otherwise, the maximum creep damage locates at the notch tip and the failure time almost keeps the same. The base notch with distance below the specimen radius is easier to generate creep failure. The notches locating in base metal and far away from filler metal are helpful to decrease the creep damage in filler metal and improve the creep life of brazed joint. (3) The inside notch dimension has a great influence on creep damage. With the increase of inside notch length, the failure time decreases gradually and the maximum creep damage locates at the notch tip. However, with the increase of inside notch width, the failure time increases and the creep failure location moves away from notch tip gradually. As the notch width reaches four times as the notch length, the failure time and location keep the same.