A review is made on the metallurgy of ultra‐low‐carbon interstitial‐free sheet steel for automotive applications. Basic principles in the development of (111) texture are summarized and differences in Ti and Nb additions are discussed. Development of sheet steel with the r‐value of 2.9 is reported as an application of the present understanding of metallurgy, by employing the currently developed technique of ferrite rolling with lubricant.

The effect of precipitate dispersion on the development of annealing texture in an interstitial free steel was investigated using a Nb-added extra-low C steel. Size and dispersion o f precipitates in a Nb-added extra-low C steel was widely changed using the same steel and keeping the grain size similar. Strong {111} recrystallization texture was developed in the specimen with coarse and sparse precipitates, but not in the specimen with fine and dense precipitates. Solute C dissolved from fine precipitates after cold rolling and during heating exists at the recovery stage and at the beginning of recrystallization in the specimen with fine and dense precipitates, but this effect cannot be considered as an important factor because of little change in {11O} texture. However, independent o f precipitate dispersion, {111} recrystallized grains recover faster than {100} oriented grains and { 111 } recrystallized grains nucleate in situ in the deformed matrices. Fine and dense precipitates strongly suppress the growth o f recrystallized grain, and results in a decrease in {111} texture. Therefore a pinning effect of precipitates for grain boundary moving during recrystallization is considered to be the most important factor controlling the recrystallization texture in an interstitial free steel. Research Article (737)

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The surface structures of polycrystalline pure metals bombarded with 20 keV 0: were observed by a SEM and their sputtered atom yields obtained by measuring the depth of crater with an interferoscope. The etch patterns produced were classified according to the binding energy of mono-oxide BMo of the target atom M and an oxygen atom; the surface become smooth as the binding energy increased. The sputtered atom yield showed similar periodicity to those obtained by noble gas ion bombardment. It was therefore concluded that the sputtered atom yield was primarily determined by physical collision of atoms in the target material and was not affected very much by the chemical reaction of implanted oxygen atoms.

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