Dear Shivraj SINGH Kasana,

Your question is not quite precise. There are many grades of these steels with different structures and chemical compositions (i.e., martensitic, DP, DP-k, DP-W, CP, TRIP). Some of them contain titanium (e.g. Docol 1100M-1500M, Docol 1200MZE-1500 MZE MS-W 1200, Optimum 900 QC-110QC, Dogal 1000 DPX, DP-K, DP-W, HCT600, Litec 600DP-1000DP, some CP grades, Litec 700-800 TRIP, RA-K40/70) others do not (e.g. Docol 450 DP-1180DP).

Titanium form MX phases X= C, N or CN. They should not be too big. Titanium carbides and carbonitrides act as grain growth inhibitors, resulting in a finer prior austenite grain size and martensite packet size. The microstructure refinement improves strength without reducing plasticity and for the martensite phase the fracture toughness can be enhanced.

In some grades (e.g. AF 1410) the titanium carbosulfide can be formed instead of chromium sulfides so the toughness can be enhanced.

Yours

M. Wrobel

Thanks a lot for giving a logical and correct answer which will help me in understanding the problem and achieving optimum results.

Regards

SHIVRAJ SINGH KASANA

M. Wrobel ansered it good.

TiN and Ti(C,N) in all size level can suppress grain growth. This is old topic.

TiN and Ti(C,N) in nano size level will lead to precipitation strengthing of steel. This is hot topic in thin steel plate for automobile. Please see some papers from ISIJ or from JFE company.

If we can use these particles well, parts of alloy can be saved.

Thanks a lot

Shivraj