Enhancing mechanical attributes and tribological performance of titanium friction stir welded joints through nanoparticle reinforcement

K Giridharan ¹, A Praveen Kumar ¹, G Chakravarthi ¹

⁰Department of Mechanical Engineering, Easwari Engineering College, Chennai, Tamilnadu, India.

Scientific Reports +

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October 6, 2025

View abstract on PubMed

Summary

Adding biochar to friction stir welding (FSW) of titanium plates significantly improves mechanical properties and wear resistance. The optimal 2 wt% biochar addition yielded superior tensile, impact, and fatigue strength, making it ideal for demanding applications.

Area Of Science

Materials Science
Mechanical Engineering
Manufacturing Technology

Background

Friction stir welding (FSW) is a key advanced manufacturing technique for joining materials.
Titanium alloys are critical in aerospace and defense due to their high strength-to-weight ratio.
Enhancing the mechanical and tribological properties of titanium welds is essential for expanding their application scope.

Purpose Of The Study

To investigate the effect of incorporating naturally derived biochar into friction stir welded titanium grade 4 plates.
To evaluate the impact of varying biochar concentrations (0-3 wt%) on mechanical properties and wear behavior.
To identify the optimal biochar content for enhancing titanium weld performance in critical applications.

Main Methods

Fabrication of 5 mm thick titanium grade 4 plates using friction stir welding with 0, 1, 2, and 3 wt% biochar.
Mechanical testing including tensile, impact, and fatigue strength analysis.
Micro-hardness, wear resistance, and coefficient of friction measurements.
Microstructural analysis using field emission scanning electron microscopy (FESEM) and scanning electron microscopy (SEM).

Main Results

Biochar addition generally improved mechanical properties compared to plain FSW titanium.
The 2 wt% biochar sample exhibited optimal tensile strength (395 MPa), impact strength (32.02 J), and fatigue strength (183 MPa).
The 3 wt% biochar sample showed enhanced micro-hardness (107 HV) and wear resistance (specific wear rate of 0.052 mm³/Nm×10⁻³, coefficient of friction of 0.25 µ).
FESEM analysis confirmed biochar dispersion and its role in grain nucleation.

Conclusions

Naturally derived biochar effectively enhances the mechanical properties and wear resistance of friction stir welded titanium.
The optimal biochar content for improved tensile, impact, and fatigue properties is 2 wt%.
The 3 wt% biochar addition is most effective for improving micro-hardness and wear resistance.
Biochar-enhanced FSW titanium presents a promising solution for aerospace components requiring high performance in wear-intensive environments.

Keywords:

Biochar Friction stir welding Mechanical characteristics Microstructure properties Titanium grade 4 Wear resistance