Inclusion shape control is being followed mainly to avoid entrapment in the inclusion sites.However in the weld this theory is not applicable in the sense that the microstructure is completely altered compared to parent plate. Debais could you please give your personal id so that i can send the relevant papers to your? regards,

Debasis Inclusion control in steel making and the role of inclusions for susceptibility control or reduce susceptibility to particular mode of cracking trend is vast. Generally, rounded inclusions is preferred due to possibility of less stress in these inclusions. Elongated or oblong or other forms of inclusions and their role to increase susceptibility for a particular mode of cracking depends on the number of inclusions (whether aluminates, silicates, combination alumino-silicate, combination of alloyed effect of inclusions - P, S, Mn, Al, Si, Ca, rare earth elements present in steel making). This depends on the chain these type of different shape inclusions can form or group together for a particular mode of cracking (even HIC or SSCC or SCC). A closed link chain with irregular shaped inclusions (mainly large inclusions) in a particular process of steel making increases susceptibility for a particular mode of cracking. For this type of cracking to predominantly occur, it is not inclusions alone play a role. It is the inherent stress present in the material combined with different types of irregular or odd shaped inclusions that have to be considered for cracking. Inclusion controlled steels is no doubt preferable but conventional steel making with even irregular shaped inclusions of different mixes (but with no possibility of too large segregations or too large close linkages) is also useful and will last equally long if inclusions are within prescribed limits in steel making processes. In welds (as Krish has suggested) it is not possible to define due to so many variables unlike in controlled steel process making. Theories on SCC or SSCC or HIC mean about too close or too desirable chain linkage of inclusion effect in promoting or aggrevating failure chance rather than sporadic presence of inclusions (whether round or irregular shaped inclusions in promoting or aggrevating failure chances). Inclusions alone, as far as theories of SCC or HIC as understood today, may not contribute significantly to these failure modes. Usually, it is a combination of stress, role and type of inclusions present, the percentage of inclusions present and likely-hood of chain formation - which most theories consider to promote HIC or SSCC or SCC. Trust this will help you C.V.Srinivsan Nishi Engineers Pvt Ltd India Aug 2,2007 E-mail: nishi @vsnl.com >Normally to avoid HIC SWC a "Ca" or "Rare Earth Element" >treated Steel is recomended for application in order to >shape control the inclusions (NMI) from elongated/ abrupt >to elliptical or round one which helps to control >susceptibility towards SWC HIC. > >Now with such Z quality steel plate what is the probability >that the weld also have shape controlled round inclusion ? >Pl. comment. >regads