Investigation of Crack Length Measurement Methods in Crack Propagation Tests at Elevated Temperature
Two crack length measurement methods used for fatigue crack growth rate test at elevated temperature,overloading and direct current potential drop (DCPD),are investigated.All fatigue tests were carried out with Compact Tension (CT) specimen.A constant fatigue loading with stress ratio R=0.5 was applied.During tests a single overload was imposed manually every a few millimeters of crack growth length.It was found from a preliminary study that an overloading ratio of 1.6 with a few second hold could generate a clearer crack marks on the fracture surface.Crack growth rate versus stress intensity factor range (da/dN –ΔK) data were calculated using secant method.According to the fractograph analysis,it was found that the fatigue crack front of investigated the super alloys is arc-shaped.In general the crack length on the surfaces is the shortest.Base on the analysis of crack profile,it was found that the crack length measured from DCPD method represents an average of crack length along the crack front.It is well in consistency with measurement from the overloading method when the crack length was characterized by its average length.
Fatigue crack growth Crack length measurement overloading method direct current potential drop(DCPD) Fatigue crack profile
Liang Wang Xinyue Huang Guangping Guo Yunming Hu
National Key Laboratory of Science and Technology on Advanced High Temperature Structural Materials, MTS Systems Corporation,Eden Prairie,Minnesota,55344,USA
国际会议
Asia Steel International conference 2012(第五届亚洲钢铁大会)
北京
英文
1-6
2012-09-23（万方平台首次上网日期，不代表论文的发表时间）