超细晶粒Ti-45 wt.% Nb合金在高周疲劳下的特征

Characteristic Features of Ultrafine-Grained Ti-45 wt.% Nb Alloy under High Cycle Fatigue.

作者信息

Mairambekova Aikol M, Eroshenko Anna Y, Oborin Vladimir A, Bannikov Mikhail V, Chebodaeva Valentina V, Terekhina Alena I, Naimark Oleg B, Dmitriev Andrey I, Sharkeev Yurii P

机构信息

Institute of Strength Physics and Materials Science of SB RAS, 2/4, Akademicheskii pr., 634055 Tomsk, Russia.

Department of Solid Mechanics, Faculty of Physics and Engineering, National Research Tomsk State University, 36, Lenina pr., 634050 Tomsk, Russia.

出版信息

Materials (Basel). 2021 Sep 17;14(18):5365. doi: 10.3390/ma14185365.

DOI:10.3390/ma14185365

PMID:34576589

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC8469476/

Abstract

The paper presents the results of fatigue-testing ultrafine-grained and coarse-grained Ti-45 wt.% Nb alloy samples under very high cycle fatigue (gigacycle regime), with the stress ratio R = -1. The ultrafine-grained (UFG) structure in the investigated alloy was formed by the two-stage SPD method, which included multidirectional forging (abc-forging) and multipass rolling in grooved rollers, with further recrystallization annealing. The UFG structure of the Ti-45 wt.% Nb alloy samples increased the fatigue limit under the high-cycle fatigue conditions up to 1.5 times compared with that of the coarse-grained (CG) samples. The infrared thermography method was applied to investigate the evolution of temperature fields in the samples under cyclic loading. Based on numerical morphology analysis, the scale invariance (the Hurst exponent) and qualitative differences for UFG and CG structures were determined. The latter resulted from the initiation and propagation of fatigue cracks in both ultra-fine grained and coarse-grained alloy samples under very high-cycle fatigue loading.

摘要

本文介绍了在应力比R = -1的超高周疲劳（千兆循环状态）下，对超细晶粒和粗晶粒Ti-45 wt.% Nb合金样品进行疲劳测试的结果。所研究合金中的超细晶粒（UFG）结构通过两步等径角挤压法形成，该方法包括多向锻造（abc锻造）和在带槽轧辊中多道次轧制，并进行进一步的再结晶退火。与粗晶粒（CG）样品相比，Ti-45 wt.% Nb合金样品的超细晶粒结构在高周疲劳条件下将疲劳极限提高了1.5倍。采用红外热成像法研究了循环加载下样品中温度场的演变。基于数值形态分析，确定了超细晶粒和粗晶粒结构的尺度不变性（赫斯特指数）和定性差异。后者是由超高周疲劳载荷下超细晶粒和粗晶粒合金样品中疲劳裂纹的萌生和扩展导致的。