The National Academies

Safety IDEA Project 38 [Active (IDEA)]

Fatigue Life Extension of Thermite Welds by Porosity Minimization

  Project Data
Funds: $99,548
Staff Responsibility: Velvet Fitzpatrick
Research Agency: University of Houston
Principal Investigator: Dr. Francisco C. Robles Hernandez
Fiscal Year: 2018

The University of Houston proposes to investigate a new method for rail life extension by improving the fatigue resistance of thermite welds. Thermite welds are known as the weakest link in railroad tracks due primarily to fatigue cracking initiated at welding voids; hence, improving their fatigue resistance is a major goal. Thermite welds can be treated as castings due to their similarities and solidification principles. An innovative method to reduce casting defects has been by means of mechanical vibration. Preliminary testing has clearly demonstrated that vibration provides significant advantages in the soundness of thermite welds through void reduction. This project aims to identify the optimum vibration conditions needed for actual thermite welds. Vibration methods have been used in a wide variety of casting process including aluminum alloys and steels. The objectives of this project are to minimize the two types of porosity, gas and shrinkage, identified in castings. The potential payoff of this project to the railroad industry includes rail life extension through the reduction of weld/rail maintenance that is in turn translated into improved safety for the North American railroads.

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