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TECHNICAL PAPERS

# Effects of Strain Hardening and Initial Yield Strength on Machining-Induced Residual Stresses

[+] Author and Article Information
Mohamed N.A. Nasr1

McMaster Manufacturing Research Institute (MMRI), Department of Mechanical Engineering, McMaster University, 1280 Main St. W., Hamilton, ON, L8S 4L7, Canadaahmedmn@mcmaster.ca

E.-G. Ng, M. A. Elbestawi

McMaster Manufacturing Research Institute (MMRI), Department of Mechanical Engineering, McMaster University, 1280 Main St. W., Hamilton, ON, L8S 4L7, Canada

1

Corresponding author.

J. Eng. Mater. Technol 129(4), 567-579 (May 23, 2007) (13 pages) doi:10.1115/1.2772338 History: Received December 21, 2006; Revised May 23, 2007

## Abstract

Finite element analysis was used in the current study to examine the effects of strain hardening and initial yield strength of workpiece material on machining-induced residual stresses (RS). An arbitrary–Lagrangian–Eulerian finite element model was built to simulate orthogonal dry cutting with continuous chip formation, then a pure Lagrangian analysis was used to predict the induced RS. The current work was validated by comparing the predicted RS profiles in four workpiece materials to their corresponding experimental profiles obtained under similar cutting conditions. These materials were AISI H13 tool steel, AISI 316L stainless steel, AISI 52100 hardened steel, and AISI 4340 steel. The Johnson–Cook (J–C) constitutive equation was used to model the plastic behavior of the workpiece material. Different values were assigned to the J-C parameters representing the studied properties. Three values were assigned to each of the initial yield strength $(A)$ and strain hardening coefficient $(B)$, and two values were assigned to the strain hardening exponent $(n)$. Therefore, the full test matrix had 18 different materials, covering a wide range of commercial steels. The yield strength and strain hardening properties had opposite effects on RS, where higher $A$ and lower $B$ or $n$ decreased the tendency for surface tensile RS. Because of the opposite effects of $A$ and ($B$ and $n$), maximum surface tensile RS was induced in the material with minimum $A$ and maximum $B$ and $n$ values. A physical explanation was provided for the effects of $A$, $B$, and $n$ on cutting temperatures, strains, and stresses, which was subsequently used to explain their effects on RS. Finally, the current results were used to predict the type of surface RS in different workpiece materials based on their $A$, $B$, and $n$ values.

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## Figures

Figure 1

Figure 2

ALE cutting model

Figure 3

Initial and final FE meshes

Figure 4

Experimental and FE RS11 profiles for (a) AISI 316L, (b) AISI H13, (c) AISI 52100, and (d) AISI 4340

Figure 5

Effect of A on RS11 distribution when (a)B=900MPa, (b)B=600MPa, and (c)B=300MPa

Figure 6

Effect of A on surface RS11

Figure 7

Effect of A on equivalent plastic strain PEEQ (B=900MPa and n=0.6)

Figure 8

Effect of A on stress-strain history of material approaching the tool tip: (a)B=900MPa and n=0.3, and (b)B=900MPa and n=0.6

Figure 9

Effect of A on PENER when B=900MPa

Figure 10

Effect of A on temperature distribution underneath tool tip when B=900MPa

Figure 11

Effect of A on PE11 distribution underneath tool tip when B=900MPa

Figure 12

Effects of B and n on RS11 distribution when (a)A=300MPa, (b)A=600MPa, and (c)A=900MPa

Figure 13

Effect of B on PEEQ, A=300MPa and n=0.6

Figure 14

Effects of B and n on stress-strain history of material approaching tool tip: (a)A=300MPa and n=0.3, and (b)A=300MPa and n=0.6

Figure 15

Effects of B and n on temperature distribution when (a)A=300MPa and (b)A=900MPa

Figure 16

Effects of B and n on PE11 distribution when A=300MPa

Figure 17

Maximum change in workpiece temperature due to the change of A or B

Figure 18

RS11 distribution in materials with A=B

Figure 19

Effects of B and n on PENER underneath tool tip when A=300MPa

Figure 20

Effect of n on PEEQ, A=300MPa and B=900MPa

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