Susceptibility of structural steel to liquid metal embrittlement during hot‐dip galvanizing in zinc 5 %‐aluminum alloy

Abstract

AbstractThe phenomenon of liquid metal embrittlement has been known in the field of batch hot‐dip galvanizing for decades. With the increasing use of zinc alloys with higher content of aluminum, the question arises regarding the specific liquid metal embrittlement effects of such alloys on structural steels. The influence of a zinc 5 %‐aluminum alloy during galvanizing on structural steel grades S355 and S700 was investigated and compared with the results obtained in a conventional pure zinc melt. Furthermore, the effect of the low‐melting alloying element tin in both the zinc 5 %‐aluminum and zinc alloys was investigated. Specimens were prepared and mechanically loaded during immersion in a liquid zinc alloy. The tests revealed the consistently ductile behavior of S355 steel without any cracking or reduction of the strain capacity under the influence of liquid zinc 5 %‐aluminum alloy and pure zinc. Steel grade S700 shows reduced deformability in zinc 5 %‐aluminum alloy but better behavior in comparison to that in pure zinc. Upon the addition of tin, the zinc 5 %‐aluminum alloy behaves very positively with no reduction in the ductility of the steel, whereas the same addition in pure zinc leads to a drastic drop in ductility.