Abstract
In the hot-dip galvanizing of steel structure, crack failures, which is well-known as Liquid Metal Embrittlement, occurs sometimes at heat affected zones after welding processes of steel structures.
We found crack failures at gas cut edges, especially at inflection of straight line cuts and at concave edges of circular cut on 40mm thick steel plates. Microscopic observation on surfaces and cross sections of gas cut zones, showed changes of the micro-structure of steel at shallow sections. These structural changes cause the embrittlement of steel plates at hot-dip galvanizing.
To simulate the embrittlement of steel plates in galvanizing, tensile tests were carried in a galvanizing bath using gas cut, mechanical cut and annealed after gas cut samples. Results showed clearly that structural changes of steel at gas cut edges played an important role in the embrittlement in galvanizing.
Calculation of thermal stress in steel structure edges at the initial stage of dipping in the galvanizing bath was attempted. From the calculated stress level due to heat expansion at edge of steel, it is estimated that the embrittlement sensitive steel may be broken in galvanizing baths.
