Other

Antonio Mascanzoni

Massimo Barteri

Giorgio Porcu

Ettore Anelli

A process for the production of austenitic stainless steel strips having as case a good weldability, comprising the operations of: solidification in a mold of a continuous casting apparatus with twin counterrotatng rolls, a strip having a thickness comprised between 1 to 5 mm and having the following composition in percent by weight: Cr 17-20; Ni 6-11; c<0.04; n<0.04; s<0.01; Mn<1.5; Si<1.0; Mo 0-3; Al<0.03; and possibly, Ti, Nb, Ta so that: Ti&plus;0.5(Nb&plus;Ta)>6C-3S with proviso that Ti>6S, or NB&plus;Ta>1C with the proviso that TI<6S; being in any case Nb&plus;Ti&plus;Ta<1.0; the remaining part being substantially Fe with a &dgr;-ferrite volume percentage comprised between 4 and 10% calculated with the formula: &dgr;-ferrite&equals;(Creq/Nieq&minus;0.728)&times;500/3 wherein: Creq/Nieq&equals;&lsqb;Cr&plus;Mo&plus;1.5Si&plus;)0.5Nb&plus;0.25Ta&plus;2.5(Al&plus;Ti)&plus;18&rsqb;/&lsqb;Ni&plus;30(C&plus;N)&plus;0.5Mn&plus;36&rsqb;; and, possibly, heating the strip at a temperature between 900 to 1200&deg; C. for a period of time less than 5 minutes. Subject of the invention is also the stainless steel strip obtained with the process and the use thereof for manufactured welded products, i.e. welded tubes.

Austenitic stainless steel strips having good weldability as cast

A process for the production of low carbon steel strips having a good combination of strength an formability, as cast, and a good weldability after the pickling by usual processes, comprising the following steps: casting, in a twin rolls continuous casting machine ( ) comprising pinch rolls ( ), a strip with a thickness comprised between 1 and 8 mm, having the following composition as weight percentage of the total weight: C 0.02-0.10; Mn 0.1-0.6; Si 0.02-0.35; Al 0.01-0.05; S<0.015; P<0.02; Cr 0.05-0.35; Ni 0.05-0.3; N 0.003-0.012; and, optionally, Ti<0.03; V<0.10; Nb<0.035, the remaining part being substantially Fe; cooling the strip in the area comprised between the casting-rolls and the pinch rolls ( ); hot deforming the strip cast through said pinch rolls ( ) at a temperature comprised between 1000 and 1300&deg; C. until reaching a thickness reduction less than 15%, in order to encourage the closing of the shrinkage porosites; cooling the strip at a speed comprised between 5 and 80&deg; C./s down to a temperature (Tavv) comprised between 500 and 850&deg; C.; and coiling into a reel ( ) the so obtainable strip.

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Rome, Italy

Antonio Mascanzoni