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Development of low alloy titanium and niobium microalloyed ultrahigh strength steel through electroslag refining

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Title Development of low alloy titanium and niobium microalloyed ultrahigh strength steel through electroslag refining
 
Creator MAITY, SK
BALLAL, NB
GOLDHAHN, G
KAWALLA, R
 
Subject mechanical-properties
inoculation
particles
esr process
ultrahigh strength steel
microalloys
austenite grain
grain refinement
ziner pinning effect
mechanical properties
characterisation
 
Description The objective of the investigation is to develop an ultrahigh strength steel ( UHSS) with a yield strength in excess of 1500 MPa, with a minimum elongation of 9 - 10% for the fabrication of rocket motor casing. Attempts have been made to develop a special steel by the electroslag refining ( ESR) process. The base alloy was prepared with a chemical composition of 0 center dot 28C - 1 center dot 0Mn-1 center dot 0Mo - 0 center dot 35V - 4 center dot 2Cr and a trace amount of S and P. This alloy has displayed yield strength of similar to 1450 MPa in the quenched and tempered condition with an average austenite grain size of similar to 65 mm. The mechanical properties were improved further by microalloying with 0? 07% Ti and Nb. The yield strengths of Ti and Nb microalloyed steels are 1500 and 1570 MPa respectively, in the as cast quenched and tempered condition. The optical, scanning electron microscope ( SEM) and transmission electron microscope ( TEM) studies confirmed that the microstructure consists of tempered lath martensite. Transmission electron microscope ( TEM) carbon replica and EDS analysis showed that the Ti( C, N) and Nb( C, N) precipitates might have helped to reduce the austenite grain size in the Ti and Nb steel. It is interesting to note that due to the smaller size of Nb ( C, N), the grain size obtained in the Nb steel is in the range of 22 - 27 mm compared to 35 - 45 mm in the Ti steel. The improvement of yield strength in Ti and Nb steel might be due to smaller austenite grains and tempered lath martensite microstructures.
 
Publisher MANEY PUBLISHING
 
Date 2011-08-17T13:36:02Z
2011-12-26T12:55:33Z
2011-12-27T05:41:11Z
2011-08-17T13:36:02Z
2011-12-26T12:55:33Z
2011-12-27T05:41:11Z
2008
 
Type Article
 
Identifier IRONMAKING & STEELMAKING, 35(5), 379-386
0301-9233
http://dx.doi.org/10.1179/174328107X203895
http://dspace.library.iitb.ac.in/xmlui/handle/10054/9883
http://hdl.handle.net/10054/9883
 
Language en