# Evaluation of Pearlite Steel Thermite Weldments’ Hydrogen Degradation for Application of Additively Manufactured Crack-Resistant Material Inserts

## TL;DR

This study examines how hydrogen affects the durability and fracture behavior of pearlite steel weldments for use in additive manufacturing.

## Contribution

The paper introduces new experimental findings on hydrogen degradation in pearlite steel weldments for additive manufacturing applications.

## Key findings

- Hydrogen absorption significantly reduces fatigue life and increases brittle fracture risk in pearlite steel weldments.
- Hydrogenated specimens show faster crack propagation and lower fracture toughness compared to non-hydrogenated ones.
- Fracture toughness of rail specimens is minimally affected by orientation in hydrogenated conditions.

## Abstract

Comprehensive investigations of the serviceability of pearlite (R260) steel have been performed and, especially, of the serviceability of their welded joints (WJ) during long-term operation in hydrogen-containing environments for application in additive manufacturing technology. It is important to estimate the durability of these steels and their WJ in hydrogen and develop the procedures of analysis of the influence of hydrogen during long-term operation. It has been experimentally observed that hydrogen absorbed (0.4 … 0.8 ppm) by the pearlite (R260) steel while welding, and subsequent operation thereof, exercises considerable influence on fatigue and brittle fractures of the constructions from which they are manufactured. Accordingly, in hydrogen-saturated (up to 4.7 ppm) specimens, the desired fatigue crack can be obtained at a considerably lower number of cycles of the same dynamic load than in non-hydrogenated ones. Increased hydrogen content can also affect crack propagation. Tests have shown that critical fracture occurs faster in hydrogenated specimens (46.6 MPa m0.5) than in non-hydrogenated ones. Also, hydrogenated specimens exhibit lower fracture toughness than their non-hydrogenated counterparts. Finally, it has been demonstrated that the fracture toughness of specimens taken from rail negligibly (49.7 … 50.7 MPa m0.5) depend on their orientation (L–S or S–L).