抄録
The excellent heat resistance properties of the "Hot-dipp" aluminized steel is by dint of the presence of the iron-aluminium layer. This layer is, however, rather brittle and hard in its nature, restricting the workability of the "Hot-dipp" aluminized steel.
For the better workability, the coating must be stronger enough for the deformation of a certain degree. The coating thickness and structure of the "Hot-dipp" aluminized steel are thus quite important factors for determining its resistance against deformation.
This is to report on the study about the relationship between the thickness and structure of the coating and the cracking susceptibility and peeling properties of the material, where the effect of the thickness and structure of the coatings on failure of the iron-aluminium layer is determined by tensile and bend tests.
The results of the tests are as follows:
1) In case the thickness of aluminium layer is same, the rupture stress works more to the thinner ironaluminium layer than to the thicker one.
2) Most of cracks appear at the boundary between aluminium layer and iron-aluminium layer and then grow toward the base steel.
3) Cracks which reach the relatively hard and brittle layer of iron-aluminium pass through the mountainpeaks and go into the base steel. There are few cracks pass the valleys.
4) In bending test, cracks take place in early stage at tension side. However, the coatings have the better adherence than in the case that it is deformed under compression.
5) When stressed in tension, the cracks at iron-aluminium layer develop vertically but not in the form of peelings.
