There are some papers about Sn usage in non grain oriented electrical steels. Sn in steel promotes grain boundary segragation during final annealing by restraining the recyristallisation which can help decreasing core losses. Unfortunately, in steelmaking / hot rolling conditions,Sn strongly promotes the hot shortness. Thus, what are the possible options to prevent hot shortness caused by Sn addition? Does the proper Ni addition in steel in order to form Sn-Ni intermetallics help or not?
Thank you in advence.
the sulpher in steel caused the hot shortness and phosphoure caused cold shortness you must decrease the sulphur in steel before treatment
Dr. Shalabi is definitely right in his remarks.
If the affinity (i.e., Gibbs free energy of formation with a sign inversion) of Sn to form Sn-Ni intermetallic compound would be higher than the segregation affinity of Sn to GB, the your suggestion of adding Ni to reduce the adverse effect of Sn to cause hot shortness or intergranual fracture. But I am not sure that is the case!
hot shortness is mainly due to sulphur present in steel. If you maintain the Mn/S ration in such a way you can prevent hot shortness. Instead looking into the Sn in steel, attack sulphur in steel and try to remove it or tackle it in some other way. You may get rid of hot shortness. And also I agree with Sn segregation along grain boundaries at high temperature. Some times excess segregation may leads to catastrophic failure.
Tin is indeed a terrible problem for the hot shortness. Tin somehow behaves like copper. Once I have experience in investigating Cu causing hot shortness, I suggest the best you can do is get rid of Sn. If the addition is mandatory, the traditional solution is the expensive addition of Ni.
Like Cu, Sn segregates on sulfides inclusions and precipitates, so reducing S is also very important. On my personal point of view, reducing inclusions is also important to reduce segregation. Addition of Si and Al is also suggested by the literature in order to reduce the selective oxidation which is the principal cause of hot shortness.
Obviously a good laboratory simulation can help to prevent the hot shortness in the continuous casting and hot rolling. Good luck!
if you have high Sn in the molten steel you have to decrease the sulfur as soon as to reduce the segregation possible and add some nickel.
As I explain before the sulpher in steel caused the hot shortness therefore try to decrease the sulpher content in molten steel by added ferromanganese and lime then the supher removed with the slag
Mn to S ratio is related to minimum Mn level which guarantee the MnS formation instead of FeS. According to existing data this ratio is variable from 4 to about 20. Electrical oriented grades using MnS as inhibitor have dropped this level even further to about 3.4-3.5.
Dear Emre Alan ,
Sulphur in steel causes the hot shortness therefore try to decrease the sulphur content in molten steel by adding ferromanganese and lime then the suphur gets removed with the slag.
Please refer to the following link for more information.
https://www.corrosionpedia.com/definition/638/hot-shortness
Regards,
GM
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