Showing papers by "Arnold R. Marder published in 1988"

The reaction between solid iron and liquid Al-Zn baths

Abstract: The reaction which occurred between iron panels and Al-Zn baths during hot dipping was investigated. Three baths were studied: 45Al-55Zn, 55Al-45Zn, and 75Al-25Zn (in wt pct) in the temperature range of 570 to 655 °C. The reaction between the iron panel and the Al-Zn bath was very severe and in all cases the iron panel was totally consumed by the bath in less than two minutes. The rapid attack of the iron panels by the Al-Zn baths was attributed to two separate causes depending on growth conditions. First, in some panels the intermediate layer which formed between the iron panel and the molten bath was nonadherent. This resulted in the direct contact of the molten bath with the iron panel at a nonequilibrium interface, which presented a large driving force and little inhibition for the reaction. Second, in panels containing an adherent alloy layer, the layer had channels of liquid Zn which extended from the molten bath to the iron panel. These channels allowed rapid transport of Zn and Al to the iron panel which resulted in a very high reaction rate. The controlling step in the reaction between the iron panel and molten Al-Zn bath was the diffusion rate of Al in the molten bath to the surface of the iron panel. The diffusion coefficient of Al in the molten bath was found to be in the range of 1 × 10-5 to 5 × 10-5 cm2/s. Microstructural, electron microprobe, and X-ray diffraction data are presented to support the above-mentioned mechanisms and conclusions.

Method of producing a Zn-Fe galvanneal on a steel substrate

Abstract: A process for producing a galvanneal layer on a steel substrate, including forming a Zn-Fe coating having a predetermined Fe content F (wt. %) on the steel substrate; and heat treating the Zn-Fe coating on the substrate from a predetermined starting temperature T 1 (°C.) to a predetermined ending temperature T 2 (°C.) at a predetermined heating rate R (°C./min.), wherein F, T 1 , T 2 , and R are selected so that the following condition is met, a.R.sup.2 +b.T.sup.2 +c.R.F.+d.R.T +e.R+f.T=g where a, b, c, d, e, f and g are predetermined constants, thereby to form a virtually 100% δ 1 phase galvanneal structure. Alternatively, the heat treatment can be preformed until the specimen temperature is just below a minimum temperature of the δ 1 phase stability range at at selected Fe content and heating rate, followed by an isothermal hold for a predetermined time period until transformation to the δ 1 phase occurs.