Study on Phase Analysis of Titanium in Steel

Abstract

In order to establish a method for phase analysis of titanium in steel, the chemical behaviors of various titanium compounds synthesized and those yielded in steel were investigated. Furthermore an investigation was made of the change in amount or form of the titanium compounds in steel by heat treatment.
The experimental results were as follows:
(1) Extraction of titanium compounds from steel was most favorably carried out by I₂-CH₃OH (10%) method. Extraction by HCl (1+1) showed a lower yield.
(2) No change was seen in nitride, oxide and sulfide of titanium in steel by usual heat treatment.
Titanium carbide, however, became soluble by heat treatment at about 1300°C, and reprecipitated by tempering.
(3) As for the oxide form, only sesquioxide was formed in the steel specimens.
(4) Titanium carbonitride could not be identified in the steels examined.
(5) The procedure for phase analysis of titanium in steel is as follows:
a) 1g of sample is decomposed by 100ml of I₂-CH₃OH (10%), under stirring, at room temperature and filtered.
(Separation of metallic Ti)
b) The extracted residue is treated in the 30ml of H₂SO₄(1+9) at 70°C for 20min and filtered again.
(Separation of fine precipitates of carbide and nitride)
c) The residue of b) is treated with 30ml of HCl (1+1) containing HF at 70°C for 20min and filtered.
(Coarse precipitate of nitride is determined with the filtrate, and that of carbide with the insoluble residue)
d) Metallic titanium is calculated by subtraction of combined titanium fraction from the total amount which is determined with use of a separate sample.