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Temperature Monitoring in Primary Metals Processing

Fasteners Heat Treatment - Hydrogen Embrittlement

After the electroplating of metal fasteners, which are used extensively in the automotive or construction industry, it is essential that the metal product is taken through a thermal heat treatment process to prevent hydrogen embrittlement. Hydrogen embrittlement is the process in which hydrogen molecules in voids within the metal, create a pressure build-up, which can lead to internal cracks and failures in the field. If the metal has not started to crack, the condition can be reversed by baking out the entrapped hydrogen, as long as this is done within one hour after acid-treating the parts. The fasteners must be heated to a target metal temperature of 200°C (392°F) and held at that temperature for 4 hours within the product basket to remove (diffuse) the harmful hydrogen.

Application Need 

To ensure that hydrogen embrittlement is not a risk to the future failure of fasteners while in use, it is necessary to monitor the baking/heat treatment process (post electroplating) to ensure that it heats the product sufficiently to diffuse any harmful hydrogen. The monitoring tool needs to provide evidence that products within the product basket at all levels achieve the critical bake conditions (Time @ Temperature). Such validation data is critical to allow supply to both automotive and construction industries, where regulatory requirements are strict.

Benefits to the customer 
  • Protect business to key automotive and construction customers providing a certified process validation report to meet all regulatory compliance
  • Prevent process issues, such as slow process temperature ramp-up, which can create significant product reject rates and lost production
  • Optimize new processes or products of different sizes with accuracy and efficiency, and allow informed correction of either line speed to setpoint temperatures to maintain correct bake conditions
  • Prevent risk of long term warranty claims from product faliures in the field or excessive construction repair costs
Thermal Profiling Systems
  • Oven Tracker System travels safely through the entire bake process, monitoring continuously without any need for problematic trailing thermocouples
  • TP3 datalogger provides up to 10 measurement points, allowing full monitoring of the process, including oven temperature and products at different locations in the product basket
  • Traceable certified profile report allows verification to CQI-9 Automotive standards that the products achieved the necessary 4 hours @ 200 °C / 392 °F

Get more information about Fluke Process Instruments solutions to this application