Aluminium nitride (AlN) nucleates with difficulty in steel, unless precipitation is enhanced by thermal or mechanical treatments. This important characteristic determines the precipitation kinetics of AlN, and accounts for the wide variations in precipitate morphology achieved following different processing histories. The most significant effect of AlN in steel is on grain size control, which directly influences hardenability, hot ductility, texture development, and mechanical properties. In addition, the accompanying removal of nitrogen from solid solution affects the strain aging characteristics, weldability, mechanical properties, and creep performance. Aluminium nitride also exerts important second order effects through its influence on the precipitation of other alloy nitrides. The precipitation of AlN can cause embrittlement and cracking phenomena in castings, continuously cast products, ingots, and rolled or forged products, However, the basic mechanisms are well understood, and the occurre...

Aluminium nitride in steel

Effects of prior plastic deformation on the distribution and morphology of AlN precipitates in α iron

The mechanical performance of batch-annealed cold-rolled aluminium-killed steel sheets depends greatly on the composition of the steel and on the thermomechanical parameters of the process. The role of carbon, aluminium, and nitrogen contents, as well as the coiling temperature, the cold-reduction percentage, and the thermal characteristics of the batch-annealing treatment, are reviewed in the light of new experimental results. A model is proposed, explaining the various effects of the processing parameters and giving a consistent interpretation of the results, which should prove valuable in predicting the quality of a sheet.MST/384

Recrystallization model for controlling mechanical properties of batch-annealed cold-rolled low-carbon aluminium-killed steel sheets

The influence of boron levels up to 40 ppm on therm value and mechanical properties of an aluminum killed steel have been investigated. It is shown that boron levels in excess of 15 ppm cause a marked deterioration inrm value from a level of 1.7 to that of 1.2. This change inrm value is associated with a characteristic change in grain shape from elongated to equiaxed, an inhibition of aluminum nitride precipitation in the annealed sheet and a lowering of the intensity of {111{ poles. The influence of boron on aluminum nitride formation is discussed.

The influence of boron upon r m value in aluminum killed drawing quality steel

The mechanical properties of Fe–0·1 C–1·5Mn–0·05V steels with varying Al contents (0·04–0·35 wt-%) were examined in the tempered condition. After hot rolling, the steels were solution treated at 1200°C for 2 h, then quenched into water. Tempering was mainly carried out at 600 or 650°C for 1 h. Hardness, tensile strength, and Charpy toughness were studied and compared with the microstructure. The precipitates were measured and identified using transmission electron microscopy and energy dispersive X-ray analysis. It wasfound that the precipitation ofVC was at a minimum in the steel containing 0·13%Al, and it is suggested that the precipitation of VC or V (C, N) was retarded at this level of Al addition. The tensile strength and lower ductile-brittle transition temperature decreased to their minimum values in the samples containing 0·1–0·15%Al, which was also believed to be a result of less VC or V(C,N) precipitation giving benefits of increased toughness and a decrease in the transition temperature...

Seiji Nishiumi

Papers

Effect of AlN Precipitation on Mechanical Properties of α -Iron

Effects of AlN Precipitation on Mechanical Properties of α-Iron