A. Wennberg, Alfa Laval, Lund, Sweden
Abstract
Fully welded plate heat exchangers are designed to optimize heat transfer without having the media in contact with anything else than the bare metal. The large number of corrugated plates provides an immense surface through which heat can be transferred from one liquid or gas to another. In a fully welded heat exchanger these plates are joined through kilometres of welds that separate the different circuits preventing the fluids or gases to mix.
During quality assurance of the fully welded heat exchangers in commercially pure titanium grade 1, microstructural deviations of TIG and Laser welds were observed. The following investigation revealed a widmanstätten like microstructure similar to high alloyed Ti and hardness values of more than 700 HV. To analyze the cause of the high hardness and the micro structure, a series of weld tests were conducted.
Summary: During quality assurance of the fully welded heat exchangers in commercially pure titanium grade 1, microstructural and hardness deviations of TIG and Laser welds were observed.
To analyze the cause of the high hardness and the micro structure, a series of weld tests were conducted.
This is a summary of what we learned from the investigation.
