Influence of Fillet Radius of Die End on Workability of Diameter-Enlarged Process

Abstract:

This study focus on the diameter-enlarged ratio, which is an important parameter for evaluating the workability of a partial diameter-enlarged process. Moreover, the study attempts to explain the influence of the fillet radius of the die end on the fatigue characteristic of the test piece after forming and the limit of the diameter-enlarged ratio without fatigue damage in the forming process. Three types of dies with different fillet deformations were used, and tensile tests were carried out after the processing was performed on three types of carbon steel. The fatigue properties of the test specimens after forming and the limit of the diameter-enlarged ratio at which no fatigue damage occurred were investigated. The results obtained are as follows: increasing the fillet radius of the die helped to ease the stress concentration at the root of the diameter-enlarged part, and shaft diameter-enlarged processing could be done without fatigue damage. Using a die having a radius equal to or larger than the appropriate fillet radius helped to increase fatigue strength, without causing fatigue damage, even if the diameter-enlarged ratio increased; notch sensitivity increased with an increase in the diameter-enlarged ratio, but the apparent notch sensitivity coefficient decreased with an increase in fillet radius in all the test pieces. A large limit for the diameter-enlarged ratio without fatigue damage may be obtained by using a die with an appropriate fillet radius.

• Periodical: Materials Science Forum (Volume 943)
• Pages: 34-42
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.943.34
• Online since: January 2019
• Authors: Xia Zhu*, Keiji Ogi, Nagatoshi Okabe
• Keywords: Diameter-Enlarged Processing Method, Diameter-Enlarged Ratio, Fatigue Notch Factor, Limit of Diameter-Enlarged Ratio, Normalized Tensile Strength, Notch Sensitivity Factor, Stress Concentration Factor

References

[1] T. Iura, K. Mori, K. Yamamoto, Y. Aono, K. Kurita, O. Nakamura, T. Sano, Local Collar Developed by Metal Plastic Deformation, Proc. of 6th ICTP, (1999)613-618.

[2] N. Okabe, T. Iura, X. Zhu, M. Tsutsumi, K. Mori, A Cold Working for Local Collar-forming with Superplasticity-like Deformation Using a New Conceptual Technology, Proc. of 4th PRICM, (2001) 2105-2108.

[3] N. Okabe, X. Zhu, T. Iura, K. Mori, Model Analysis for a Clod Working of Collar-forming in a Metal Bar with Local Superplastic Deformation by a New Conceptual Technology, Proc. 7th ICTP, (2002) 871-976.

[4] T. Iura, N. Okabe, X. Zhu, Development of Novel Plastic Working Process for Producing a Collar on a Round Shaft, J. of JSTP, 44-514 (2003) 45-49.

[5] T. Iura, N. Okabe, X. Zhu, Fatigue Properties and Fatigue Damage in a Round Shaft with a Collar Formed by a Novel Processing Method for Enlarging Diameter, J. of JSTP, 45-516 (2004)33-37.

[6] X. Zhu, N. Okabe, K. Ogi, M. Takahashi, Fatigue Strength of Shaft with Diameter Enlarged Partially by Cyclic Bending and Axial Compressive Loading, Appl. Mech. Mater., Vols. 217-219 (2012) 2346-2350.

DOI: 10.4028/www.scientific.net/amm.217-219.2346

[7] X. Zhu, H. Takahashi, K. Ogi, M. Takahashi, N. Okabe, Investigation of Crack Generation in a Notch during Diameter-Enlarged Working Method Processing, Key Eng. Mater., Vol. 656-657 (2015)473-478.

DOI: 10.4028/www.scientific.net/kem.656-657.473

[8] M. Nishida, Stress concentration (revised version), Morikita Publishing Co., Ltd., Tokyo, 1988, p.645.

[9] Japan Society for Materials Science, Fatigue design manual, Yokendo Publishing Co., Ltd., 1995, p.28.