American Welding Society Forum
Can an increase of Ti composition in high strength low alloy steel increases also deformation during welding?
The common Ti composition in Q345 Chinese grade steel plate is 0.2% but the actual composition is listed as 0.58% in the CMTR. The welding process is SAW with 1.6mm dia. to form a b-up beam with a fillet weld leg of 4-5mm in web and flange thickness of 4-5 to 6mm respectively and double side fillet welded with a calculated heat input from 1.2 - 1.5KJ/mm. The depth of the web is only around from 280-400mm.
It is noticeable that the waviness in web are inevitable, does the increase in Ti is the cause of it?
Titanium is often used as a deoxidizer, but it can be used as a microalloy. The following is from wikipedia"
Microalloyed steel is a type of alloy steel that contains small amounts of alloying elements (0.05 to 0.15%), including niobium , vanadium, titanium, molybdenum , zirconium , boron , and rare-earth metals. They are used to refine the grain microstructure or facilitate precipitation hardening.
However, does the written below make the steel plates with higher percentage of Ti vulnerable to waviness after welding or it is within the welding sequences, sizes, etc?
"An unstable creep is the deadliest enemy for titanium. Creep is basically the slow and progressive deformation of metal under its own weight or constant weight or constant loading at constant temperatures with respect to time.
In simple words, creep is destruction of a material over time due to its own weight. Titanium has an unstable creep, meaning it is not predictable. Therefore, it is used with caution. Although creep can be reduced by processing the metal, it cannot be completely eliminated".
The titanium is a microalloy addition. It is not a main constituent of the alloy system. Don't confuse the properties of titanium as a base metal and titanium as an alloying constituent.
A quick internet search may be sufficient to provide you with the mechanism by which the microalloy functions.
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