Ti49.8Ni50.2合金丝材的热机械循环疲劳和相变研究

Thermo-Mechanical Cycling Fatigue and Transformation Behavior of Ti49.8Ni50.2 Alloy Wire

摘要:

研究了热处理对Ti49.8Ni50.2合金丝材的相变、力学性能以及热机械循环疲劳的影响。结果表明：随着退火温度的升高，R→B19′相变温度升高，B2→R相变温度降低，873 K退火时B2→R和R→B19′相变重合。当退火温度(Ta)低于823 K时，试样处于回复阶段，σM随退火温度升高有小幅度下降，723 K退火试样在热机械循环中获得最大稳定回复应变， 疲劳寿命随退火温度的升高略有提高；退火温度高于823 K时，试样发生再结晶，σM剧烈下降，稳定回复应变剧烈降低，而疲劳寿命由103升至104数量级

Abstract:

The effects of heat treatment on transformation behavior, properties and thermo-mechanical cycling fatigue of Ti49.8Ni50.2 alloy wire were investigated. With increasing of annealing temperature, R→B19′ transformation temperatures increase, while B2→R transformation temperatures decrease. The two transformations temperatures will overlap upon annealing at 823 K. Recovery occurs in the specimen annealed below 823 K, σM decreases slightly with the increase of annealing temperature, The specimen annealed at 723 K shows the largest stable recovery strain while its upon annealing above 823 K, the recrystallization of the specimen will occur, its σM and stable recovery strain decrease sharply, while its fatigue life increases from 103 to 104 magnitudes