# Yield Load Solutions for SE(B) Fracture Toughness Specimen with I-Shaped Heterogeneous Weld

^{1}

^{2}

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## Abstract

**:**

## 1. Introduction

_{YW}and σ

_{YB}represent the yield strength of the weld metal and the yield strength of the base metal (BM), respectively, while M < 1 refers to under-matching (UM) and M > 1 to over-matching (OM).

## 2. Problem Description and Investigation Plan

## 3. Finite Element Analysis

_{OM}= 2, 1.5 and 1.19 and under-match metal with mismatch factor M

_{UM}= 0.86, 0.75 and 0.5. Yield strength and mismatch factors M

_{UM}= 0.86 and M

_{OM}= 1.19 were chosen due to later comparison to experimental results.

## 4. Results of Finite Element Analysis

#### 4.1. Yield Load Solutions for a Crack in the Over-Matched Part of the Weld

_{UM}. Therefore, the solutions were the values 0.5, 0.75 and 0.86 because the dominant metal is in front of the crack. Although the solutions were these values, it is noticeable that they are actually slightly larger, which is a consequence of the formation of the yield zone partially through the over-matched metal too, which has a higher value of the mismatch factor M

_{OM}.

_{OM}= 1.19 and M

_{UM}= 0.86.

_{OM}and M

_{UM}differ significantly, while the solutions for combinations of metals with closer values of M

_{OM}and M

_{UM}approach the values of 1 of the base metal. For example, for the combination of metals M

_{OM}= 2 and M

_{UM}= 0.5, the solutions range from 0.5 to 1.6, and for the combination of M

_{OM}= 1.19 and M

_{UM}= 0.86, the solutions are almost everywhere uniform and closer to the value 1.

_{OM}, under-match strength mismatch M

_{UM}, the weld width H and the crack length a/W:

#### 4.2. Yield Load Solutions for a Crack in the Under-Matched Part of the Weld

_{OM}and M

_{UM}approached the values of 1 of the base metal. For example, for the combination of M

_{OM}= 2 and M

_{UM}= 0.5, the solutions ranged from 0.9 to 2, and for the combination of M

_{OM}= 1.19 and M

_{UM}= 0.86, the solutions were almost uniform and were everywhere closer to the value of 1.

## 5. Experimental Investigation

## 6. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

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**Figure 1.**Idealization of repaired I-shaped butt-welded joint: (

**a**) heterogeneous welded joint; (

**b**) idealized heterogeneous welded joint.

**Figure 2.**Numerical model: (

**a**) homogeneous weld for verification; (

**b**) heterogeneous weld; (

**c**) detail of finite element mesh of homogeneous weld for verification; (

**d**) key-points for variation of weld width H and crack length a; (

**e**) detail of finite element mesh of model with heterogeneous weld.

**Figure 4.**Mismatch yield loads for the heterogeneous weld and for a crack in the over-matched part of the weld: (

**a**) shallow crack—a/W = 0.1; (

**b**) medium length crack—a/W = 0.3; (

**c**) deep crack—a/W = 0.5.

**Figure 5.**Formation of the yield zone in a heterogeneous weld with a crack in the over-matched part of the weld for varying weld width H and constant crack length a/W = 0.5.

**Figure 6.**Mismatch yield loads for the heterogeneous weld and for a crack in the under-matched part of the weld: (

**a**) shallow crack—a/W = 0.1; (

**b**) medium length crack—a/W = 0.3; (

**c**) deep crack—a/W = 0.5.

**Figure 7.**Tensile and fracture toughness specimens: (

**a**) position and orientation of tensile specimens; (

**b**) fracture toughness specimen notch orientation; (

**c**) weld arrangement; (

**d**) three point bending specimen SE(B) for fracture toughness testing.

**Figure 8.**Experimentally obtained results: (

**a**) loading curves for specimens with a crack in the OM and UM part of the weld; (

**b**) comparison of experimentally obtained maximum load with a yield load obtained by numerical analysis for a crack in the OM and UM part of the weld.

Material | R_{p0.2}, MPa | R_{m}, MPa | E, GPa | M |
---|---|---|---|---|

Base metal (NIOMOL 490) | 545 | 648 | 202 | - |

Over-matched (FILTUB 75) | 648 | 744 | 184 | 1.19 |

Under-matched (VAC 60) | 468 | 590 | 206 | 0.86 |

Material | C | Si | Mn | P | S | Cr | Mo | Ni |
---|---|---|---|---|---|---|---|---|

Base metal (NIOMOL 490) | 0.123 | 0.33 | 0.56 | 0.003 | 0.002 | 0.57 | 0.34 | 0.13 |

Over-matched (FILTUB 75) | 0.040 | 0.16 | 0.95 | 0.011 | 0.021 | 0.49 | 0.42 | 2.06 |

Under-matched (VAC 60) | 0.096 | 0.58 | 1.24 | 0.013 | 0.160 | 0.07 | 0.02 | 0.03 |

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**MDPI and ACS Style**

Konjatić, P.; Katinić, M.; Kozak, D.; Gubeljak, N. Yield Load Solutions for SE(B) Fracture Toughness Specimen with I-Shaped Heterogeneous Weld. *Materials* **2022**, *15*, 214.
https://doi.org/10.3390/ma15010214

**AMA Style**

Konjatić P, Katinić M, Kozak D, Gubeljak N. Yield Load Solutions for SE(B) Fracture Toughness Specimen with I-Shaped Heterogeneous Weld. *Materials*. 2022; 15(1):214.
https://doi.org/10.3390/ma15010214

**Chicago/Turabian Style**

Konjatić, Pejo, Marko Katinić, Dražan Kozak, and Nenad Gubeljak. 2022. "Yield Load Solutions for SE(B) Fracture Toughness Specimen with I-Shaped Heterogeneous Weld" *Materials* 15, no. 1: 214.
https://doi.org/10.3390/ma15010214