1988 Volume 74 Issue 12 Pages 2353-2360
It was found that the mixture of ammonium sulfate, cupric sulfate and sulfuric acid was suitable for the decomposition of BN in steel. Using this mixture, boron in steels and in the precipitates was analyzed and the precipitation behavior of boron in steels was discussed.
1) BN isolated from steel was decomposed by fuming sulfuric acid in the above described mixture for 1 hour. The maximum quantity of coexisting water should be 0.2 ml to prevent the loss of boron.
2) After steel matrix was dissolved by nitric acid, BN in the residue was decomposed by fuming sulfuric acid in the above mixture with the addition of phosphoric acid for 25 minutes.
3) BN was precipitated in non-equilibrium state at various temperatures of heat treatment of steel. BN precipitated at 500°C changed into the dual phases comprising borocarbide and AIN with increasing the holding time or the holding temperature for heating of steel.