Showing papers by "Arnold R. Marder published in 1989"

The effects of silicon on the reaction between solid iron and liquid 55 wt pct Al-Zn baths

Abstract: The effect of various silicon levels on the reaction between iron panels and Al-Zn-Si liquid baths during hot dipping at 610°C was studied. Five different baths were used: 55Al−0.7Si−Zn, 55Al−1.7Si−Zn, 55Al−3.0Si−Zn, 55Al−5.0Si−Zn, and 55Al−6.88Si−Zn (in wt pct). The phases which formed as a result of this reaction were identified as Fe2Al5 and FeAl3 (binary Fe−Al phases with less than 2 wt pct Si and Zn in solution),T1, T2, T4, T8, andT 5H (ternary Fe−Al−Si phases), andT 5C (a quaternary Fe−Al−Si−Zn phase). Compositional variations through the reaction zone were determined. The phase sequence in the reaction zone of the panel dipped for 3600 seconds in the 1.7 wt pct Si bath was iron panel/(Fe2Al5+T 1)/FeAl3/(T 5H+T 5C)/overlay. In the panel dipped for 1800 seconds in the 3.0 wt pct Si bath the reaction zone consisted of iron panel/Fe2Al5/(Fe2Al5+T 1)/T 1/FeAl3/(FeAl3+T 2)/T 5H/overlay. In the panel dipped for 3600 seconds in the 6.88 wt pct Si bath the phase sequence was iron panel/Fe2Al5/(Fe2Al5+T1)/(T1+FeAl3)/(T1+T2)/T2/T8/T4/overlay. The growth kinetics of the reaction zone were also studied. A minimum growth rate for the reaction zone which formed from a reaction between the iron panel and molten Al−Zn−Si bath was found in the 3.0 wt pct Si bath. The growth kinetics of the reaction layers were found to be diffusion controlled in the 0.7, 1.7, and 6.88 wt pct Si baths, and interface controlled in the 3.0 and 5.0 wt pct Si baths. The presence of the interface between theT2/T5H, Fe2Al5/T 1, orT 1/FeAl3 phases is believed responsible for the interface controlled growth kinetics exhibited in the 3.0 and 5.0 wt pct Si baths.

A METHOD OF PRODUCING A Zn-Fe GALVANNEAL COATING ON A STEEL SUBSTRATE AND THE PRODUCT THEREBY FORMED

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 T1 (°C) to a predetermined ending temperature T2 (°C) at a predetermined heating rate R (°C/min.), wherein F, T1, T2, and R are selected so that the following condition is met, a.R?2 + b.T2? + 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 performed until the specimen temperature is just below a minimum temperature of the δ1 phase stability range at a selected Fe content and heating rate, followed by an isothermal hold for a predetermined time period until transformation to the δ1 phase occurs.