基于堆焊成形钛合金高周疲劳实验数据的R-S-N模型  

R-S-N Mathematical Model Based on TC18 by BW High Cycle Fatigue Test Data

作　　者：朱良[1] 王晶[1] 李晓慧[1] 锁红波[2] 张亦良[1] 

机构地区：[1]北京工业大学机械与应用电子技术学院,北京100022 [2]北京航空制造工程研究所高能束流加工技术重点实验室,北京100024

出　　处：《材料研究学报》2015年第9期714-720,共7页Chinese Journal of Materials Research

摘　　要：针对应力比对疲劳寿命影响的问题,以TC18钛合金堆焊成形(利用多层堆焊的方法制备)试样为研究对象,进行了3种应力比(R=0.5、R=0.06、R=-1)的疲劳实验,得出相应的疲劳极限,应用"应力幅值寿命模型"和"三参数寿命模型"得到6条S-N曲线。根据裂纹扩展速率与疲劳寿命的积分关系,以两种疲劳寿命数学模型为基础,系统地研究了应力比(R)与疲劳寿命曲线(S-N)的关系,提出了考虑应力比的疲劳寿命(R-S-N)数学模型。根据本文提出的修正公式,建立了适用TC18钛合金堆焊成形材料的两种R-S-N数学模型,结果表明:用应力幅值寿命模型可对中等疲劳寿命区进行准确的预测,而三参数寿命模型更适合中长寿命区域的预测。提出的两种R-S-N数学模型与实验值吻合良好,并可在工程上预测任意应力比下的疲劳寿命曲线。For the influence of stress ratio on fatigue life, fatigue tests of TC18 titanium alloy produced by build-up welding （TC18 by BW） samples were carried out under three stress ratios （R=-0.5 R=- 0.06, R=-1）, to draw three fatigue limits and 6 S-N curves of ＂stress amplitude life model ＂ and ＂three-parameter model ＂. Based on the integral relationship of the crack growth rate and fatigue life and considering both of mathematical models of fatigue life, a systematic investigation of the relationship between stress ratio （R） and fatigue life curve （S-N） was performed to build the fatigue life mathematical model （R- S-N）. According to the modified formula proposed in this paper, the establishment of two R-S-N mathe- matical models, applicable for TC18 by BW materials. The results show that ＂stress amplitude＂ model can accurately predict moderate fatigue life, and ＂three-parameter fatigue＂ model is more suitable for the prediction of long-life area. The predictive value of two proposed R-S-N mathematical models are in bet- ter agreement with the experimental values, they can accurately predict the fatigue curve under any stress ratio in engineering.

关 键 词：材料科学基础学科 应力比 疲劳寿命 疲劳极限 R—S-N数学模型 

分 类 号：TG113[金属学及工艺—物理冶金]