# Mechanism of Blunt Punching Tools’ Influence on Deformation and Residual Stress Distribution

^{1}

^{2}

^{3}

^{4}

^{5}

^{6}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Material Preparation

#### 2.2. Microstructure Analysis

#### 2.3. Residual Stress Determination

#### 2.4. Finite Element Simulation

## 3. Results and Discussions

#### 3.1. Deformation during Punching

#### 3.2. Residual Stress Distribution after Punching

_{11}direction on the surface of the cutting edge could be compared with the experimental results. The residual stress distributions of simulated and experimental results (Figure 9a) indicate the presence of tensile residual stress on the surface of the cutting edge after punching. The tensile residual stress was relatively weak with a maximum value about 100 MPa, which is consistent with the results of Mori et al. [4].

#### 3.3. Formation Mechanism of Tensile Stress on the Surface

## 4. Conclusions

- (a)
- After the punching process using blunt tools, a large burr was formed and the cutting edge could be divided to three distinct areas: a highly deformed area, a bent area with moderate deformation and a non-deformed area. The closer to the cutting edge, the greater the plastic deformation.
- (b)
- The ribbon grains were formed in the highly deformed area, very close to the cutting edge. Dislocation slip and shear band formation were the deformation mechanisms. The mechanism of deformation in the bent area corresponds to only dislocation slip.
- (c)
- Tensile residual stress on the surface of punched sheet was observed, and the distribution width of tensile residual stress was about 0.33 mm.
- (d)
- The formation of tensile residual stress on the surface of a punched sample depends on the formation of a bent area with the blunt tools. Punch tools with high wear will form a large bending area at the cutting edge with a large and deep tensile stress region on the surface, which will be retained after punching.

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

## References

- Saleem, A.; Alatawneh, N.; Chromik, R.R.; Lowther, D.A. Effect of Shear Cutting on Microstructure and Magnetic Properties of Non-Oriented Electrical Steel. IEEE Trans. Magn.
**2016**, 52, 1–4. [Google Scholar] [CrossRef] - Peksoz, A.; Erdem, S.; Derebasi, N. Mathematical model for cutting effect on magnetic flux distribution near the cut edge of non-oriented electrical steels. Comput. Mater. Sci.
**2008**, 43, 1066–1068. [Google Scholar] [CrossRef] - Cao, H.; Hao, L.; Yi, J.; Zhang, X.; Luo, Z.; Chen, S.; Li, R. The influence of punching process on residual stress and magnetic domain structure of non-oriented silicon steel. J. Magn. Magn. Mater.
**2016**, 406, 42–47. [Google Scholar] [CrossRef] - Mori, K.; Abe, Y.; Kidoma, Y.; Kadarno, P. Slight clearance punching of ultra-high strength steel sheets using punch having small round edge. Int. J. Mach. Tools Manuf.
**2013**, 65, 41–46. [Google Scholar] [CrossRef] - Naumoski, H.; Maucher, A.; Herr, U. Investigation of the influence of global stresses and strains on the magnetic properties of electrical steels with varying alloying content and grain size. In Proceedings of the 2015 5th International Electric Drives Production Conference (EDPC), Nuremberg, Germany, 15–16 September 2015; pp. 1–8. [Google Scholar]
- Aydin, U.; Rasilo, P.; Martin, F.; Belahcen, A.; Daniel, L. Effect of simultaneous plastic and elastic deformation on magnetic properties of electrical steel sheets. In Proceedings of the 64th Annual Conference on Magnetism and Magnetic Materials (MMM 2019), Las Vegas, NV, USA, 4–8 November 2019. [Google Scholar]
- Laakso, S.V.A.; Aydin, U.; Krajnik, P. Verification of electric steel punching simulation results using microhardness. Int. J. Adv. Manuf. Technol.
**2021**, 112, 2027–2036. [Google Scholar] [CrossRef] - Singh, U.P.; Streppel, A.H.; Kals, H.J.J. Design study of the geometry of a punching/blanking tool. J. Mater. Process. Technol.
**1992**, 33, 331–345. [Google Scholar] [CrossRef] [Green Version] - Saleem, A.; Goldbaum, D.; Brodusch, N.; Gauvin, R.; Chromik, R.R. Microstructure and mechanical property connections for a punched non-oriented electrical steel lamination. Mater. Sci. Eng. A
**2018**, 725, 456–465. [Google Scholar] [CrossRef] - Chen, Y.-W.; Tsai, Y.-T.; Tung, P.-Y.; Tsai, S.-P.; Chen, C.-Y.; Wang, S.-H.; Yang, J.-R. Phase quantification in low carbon Nb-Mo bearing steel by electron backscatter diffraction technique coupled with kernel average misorientation. Mater. Charact.
**2018**, 139, 49–58. [Google Scholar] [CrossRef] - Tiwari, A.K.; Kumar, A.; Kumar, N.; Prakash, C. Investigation on micro-residual stress distribution near hole using nanoindentation: Effect of drilling speed. Meas. Control
**2019**, 52, 1252–1263. [Google Scholar] [CrossRef] [Green Version] - Suresh, S.; Giannakopoulos, A.E. A new method for estimating residual stresses by instrumented sharp indentation. Acta Mater.
**1998**, 46, 5755–5767. [Google Scholar] [CrossRef] - Pathak, R.K.; Ravi Kumar, A.; Ananthasuresh, G.K. Simulations and experiments in punching spring-steel devices with sub-millimeter features. J. Manuf. Process.
**2013**, 15, 108–114. [Google Scholar] [CrossRef] - He, J.; Li, S.; Dong, L. Experiments and FE simulation of edge cracking considering prehardening after blanking process. Int. J. Mater. Form.
**2019**, 13, 547–560. [Google Scholar] [CrossRef] - Subramonian, S.; Altan, T.; Ciocirlan, B.; Campbell, C. Optimum selection of variable punch-die clearance to improve tool life in blanking non-symmetric shapes. Int. J. Mach. Tools Manuf.
**2013**, 75, 63–71. [Google Scholar] [CrossRef] - Wang, X.; Shi, J. Validation of Johnson-Cook plasticity and damage model using impact experiment. Int. J. Impact Eng. IJIE
**2013**, 60, 67–75. [Google Scholar] [CrossRef] - Dabboussi, W.; Nemes, J. Modeling of ductile fracture using the dynamic punch test. Int. J. Mech. Sci.
**2005**, 47, 1282–1299. [Google Scholar] [CrossRef] - Poizat, C.; Campagne, L.; Daridon, L.; Ahzi, S.; Husson, C.; Merle, L. Modeling and simulation of thin sheet blanking using damage and rupture criteria. Int. J. Form. Process.
**2005**, 8, 29–47. [Google Scholar] [CrossRef] - Børvik, T.; Hopperstad, O.; Berstad, T. On the influence of stress triaxiality and strain rate on the behaviour of a structural steel. Part II. Numerical study. Eur. J. Mech. A-Solids
**2003**, 22, 15–32. [Google Scholar] [CrossRef] - Chen, Z.H.; Tang, C.Y.; Lee, T.C. An investigation of tearing failure in fine-blanking process using coupled thermo-mechanical method. Int. J. Mach. Tools Manuf.
**2004**, 44, 155–165. [Google Scholar] [CrossRef] - Jin, X.; Fu, B.-Q.; Zhang, C.-L.; Liu, W. Evolution of the texture and mechanical properties of 2060 alloy during bending. Int. J. Miner. Metall. Mater.
**2015**, 22, 966–971. [Google Scholar] [CrossRef] - Raabe, D. Recovery and recrystallization: Phenomena, physics, models, simulation. Phys. Metall.
**2014**, 23, 2291–2397. [Google Scholar] [CrossRef] - Chan, L.C.; Leung, Y.; Lee, T.; Fan, J.; Tang, C.Y. Numerical simulation for fine-blanking—A new approach. Mater. Sci. Eng. A
**2004**, 364, 207–215. [Google Scholar] [CrossRef] - Romanowski, W.P. Spravochnik po Holodnoj Shtampovke, 6. Leningrad Mashinostroenie, Leningradskoe Otdelenie. 1979, pp. 15–16. Available online: https://spbarchives.ru/infres/-/archive/cgantd/R-53 (accessed on 17 April 2019).

**Figure 1.**(

**a**) GOS and grain size distributions of initial material. (

**b**) Orientation distribution function (ODF) section plot (φ

_{2}= 45°) for initial material, and the dotted black line shows the ideal position of γ fiber.

**Figure 2.**Geometric illustration of the punching experiment. (${d}_{1}$ is the radius of the punch; ${d}_{2}$ is the inner diameter of the die; ${d}_{c}$ is the chamfer distance of the punch; ${\theta}_{c}$ is the chamfer angle of the punch; ${r}_{1}$ is the fillet radius of the blank holder; ${r}_{2}$ is the fillet radius of the die; ${c}_{1}$ is the difference value in radius between the punch and blank holder;${c}_{2}$ is the difference value in radius between the punch and die; $t$ is the thickness of the silicon sheet).

**Figure 3.**(

**a**) Diagram of loading, pressure maintaining and unloading for the nanoindentation test; (

**b**) illustration of the locations of the test points in the surface of a punched circular sample.

**Figure 5.**Geometry of tensile samples used to obtain the parameters of JC plasticity and damage models.

**Figure 6.**(

**a**) Equivalent plastic strain (PEEQ) distribution at the cutting edge after punching, obtained by FE simulation with blunt tools. (

**b**) Simulation of punching process and formation of three areas at cutting edge.

**Figure 7.**(

**a**) Blank map obtained from EBSD analysis at the cutting edge of the punched sample. (

**b**) Diagram of burr, obtained by FE simulation with blunt tools. Black lines shown in (

**a**) are the grain boundaries with a misorientation greater than 15°. The brown line and blue area at the end of the burr correspond to the direction of tearing failure and the removed part of burr after tearing failure, respectively.

**Figure 8.**(

**a**) KAM distribution map and (

**b**) inverse pole figure (IPF) map obtained from EBSD analysis at the cutting edge of a punched sample; (

**c**) KAM distribution map of red frame shown in area 2 of (

**a**); (

**d**) KAM distribution map; and (

**e**) IPF map of black dotted frame shown in area 3 of (

**a**). Black lines shown in (

**a**,

**c**,

**d**) are the grain boundaries with misorientation greater than 15°.The black dotted circular frame and red lines in (

**e**) show the presence of a shear band formed during punching.

**Figure 9.**(

**a**) Residual stress distribution on the surface after punching. Blue and red lines show, respectively, the simulated residual stress in S

_{11}direction and the residual stress tested by nanoindentation. (

**b**) Residual stress distribution in the longitudinal section of the cutting edge. The red arrow indicates the extraction path of the simulation results in (

**a**).

**Figure 10.**(

**a**) Simulated distribution of residual stress in S

_{11}direction at the beginning of punching. (

**b**) Diagram of stress distribution for free bent area and the position near the contact between die and material. Simulated distribution of residual stress in S

_{11}direction (

**c**) during punching, (

**d**) after fracture initiation and (

**e**) after complete fracture and removal of mold. Number 2 indicates bent area 2. The letters A, B, C and D were used to distinguish the regions in area 2 with different states of residual stress. The dotted lines in (

**a**,

**b**) are used to distinguish the depth region A with tensile stress; the green dotted circle in (

**d**) corresponds to the area with high tensile stress.

**Table 1.**Nominal chemical composition and mechanical properties (obtained by tensile tests) of 50WW1300.

Alloy | Chemical Composition | Mechanical Properties | |||||
---|---|---|---|---|---|---|---|

Si | Al | Mn | Fe | Tensile Strength (MPa) | Elongation | Young’s Modulus (GPa) | |

50WW1300 | 0.63 | 0.23 | / | Bal. | 384.71(RD)387.79(TD) | 44.40%(RD)45.01%(TD) | 184 |

**Table 2.**Dimensions corresponding to the geometric illustration in Figure 2.

Clearance | d_{1} (mm) | d_{2} (mm) | d_{c} (mm) | θ_{c} | r_{1} (mm) | r_{2} (mm) | c_{1} (mm) | c_{2} (mm) | t (mm) |
---|---|---|---|---|---|---|---|---|---|

4% | 29.980 | 30.000 | 0.350 | 45° | 0.005 | 0.050 | 0.020 | 0.010 | 0.500 |

**Table 3.**Dimensions and stress triaxiality of tensile samples (shown in Figure 5) used to obtain the parameters of JC plasticity and damage models.

Sample | Stress Triaxiality | L (mm) | d (mm) | R (mm) |
---|---|---|---|---|

A | 0.335 | 110 | 10 | 15 |

B | 0.338 | 110 | 10 | 5 |

C | 0.346 | 110 | 10 | 2 |

D | 0.358 | 110 | 10 | 1 |

E | 0.380 | 110 | 10 | 0.5 |

Parameter | A (Mpa) | B (Mpa) | C | n |
---|---|---|---|---|

Value | 267 | 749.95 | 0.064 | 0.8 |

**Table 5.**Failure parameters ${d}_{1}-{d}_{4}$ used in the JC damage criterion (obtained with tensile tests).

Failure Parameter | d_{1} | d_{2} | d_{3} | d_{4} |
---|---|---|---|---|

Value | 0.028 | 3.2*E^{11} | 84.27 | −0.4 |

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |

© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Wang, W.; Fang, X.; Wang, X.; Andrieux, M.; Ji, V.
Mechanism of Blunt Punching Tools’ Influence on Deformation and Residual Stress Distribution. *Metals* **2021**, *11*, 2029.
https://doi.org/10.3390/met11122029

**AMA Style**

Wang W, Fang X, Wang X, Andrieux M, Ji V.
Mechanism of Blunt Punching Tools’ Influence on Deformation and Residual Stress Distribution. *Metals*. 2021; 11(12):2029.
https://doi.org/10.3390/met11122029

**Chicago/Turabian Style**

Wang, Wei, Xiang Fang, Xuanguo Wang, Michel Andrieux, and Vincent Ji.
2021. "Mechanism of Blunt Punching Tools’ Influence on Deformation and Residual Stress Distribution" *Metals* 11, no. 12: 2029.
https://doi.org/10.3390/met11122029