Evaluation of Friction Coefficient by Simulation in Bulk Metal Forming Process

Abstract

With the objective of evaluating the accuracy of the upper-bound theory for calculating the average Tresca friction coefficient m in the hot forging process, we performed simulations using different values of m in each compression process to high strain levels. It was found that the upper-bound theory is not applicable at high strain levels, because the contact surface of the cylindrical sample is composed of an originally flat end surface and the annular portion formed by the contact of the lateral surface with the anvil surface. The relation among P ¼ R m H R t H 0 ; true strain, and m could be expressed by a 0 þ a 00 e þ a 000 e 2 À P À Á þ b 0 þ b 00 e þ b 000 e 2 À Á m þ c 00 e þ c 000 e 2 À Á m 2 ¼ 0: Here, the m values obtained were in good agreement with the actual ones used in the simulations. The value of m of the arbitrary geometry cylindrical sample could also be directly read from a contour map with a relationship among nominal strain, parameter B of the corresponding standard sample, and m.

A study of the dynamic recrystallization kinetics of V-microalloyed medium carbon steel

“…To correct for minor friction effects, a series of hot compression tests at various strains were carried out in Gleeble to calculate barreling factors [14]. The measured flow curves were corrected for the friction effect using the friction coefficients obtained from the barreling factors.…”

Hot Deformation Behavior of a Nickel-modified AISI 4330 Steel

“…Several mathematical relations have been proposed in the literature in order to compensate for the friction effect. 21,22) In the present work, the constant friction factor model proposed by Dieter 23) was used as it has been successfully applied to steels:…”

Development of Novel Methods for Compensation of Stress-strain Curves

“…In our previous study, 10) a relatively precise identification of the friction coefficient of a cylindrical sample was conducted by using DEFORM-3D finite element method (FEM) software. For a cylindrical sample with Rastegaev geometry (initial height/diameter = 1.…”

“…(11), the following equation for correcting the stress-strain curve for a sample with Rastegaev geometry is obtained: where m can be calculated using the methodology developed in our previous study. 10) The stress without the influence of friction can be compensated by inserting the other parameters of Table 1 into Eq. (14), regardless of the experimental conditions or of the characteristics of the material.…”