The paper entitled "Monitoring thermal cycles in multi-pass welding" by Maria
Asuncion Valiente Bermejo, Kjell Hurtig, Vahid Hosseini, Leif Karlsson and
Lars-Erik Svensson (all of them with the Welding Research Group at University
West) was presented at the 7th Swedish Production Symposium (SPS-16), held in Lund (Sweden) in October 2016.
Here you have the summary:
Differently
from any previous investigation in welding, this research work presents a novel
development that allows temperature to be measured and recorded simultaneously
with up to 32 thermocouples in different locations of a welding joint. Four
experiments were designed to optimise the measurement technique by comparing
the performance of three types of thermocouples (K, N, C) insulated with
different materials and varying the insertion technique of the thermocouples in
the joint. Results showed that type-K thermocouple had the best performance and
proved that glass fibre insulation provided better protection than Inconel. The
optimised measurement procedure developed in this work enables to monitor the
thermal cycles in multi-pass welds. That information is essential in multi-pass
welding of materials such as super duplex stainless steels, carbon steels or
nickel alloys, as heating them repeatedly makes them susceptible to the
formation of brittle phases and in turn it influences their mechanical and
corrosion properties. This technique could be really important for future
applications such as temperature modelling or prediction of mechanical
properties and microstructure in relation to the thermal cycle experienced by alloys
susceptible to the formation of undesirable phases.