The Ferritic Solution - Euro Inox

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group 1 ferritics are best suited to non-severe conditions, such as inside the home (where the material is either not exposed to water contact or gets regularly wiped dry) or outdoors in contexts where some superficial corrosion is acceptable. in such contexts, this group of ferritics has a longer life than carbon steel,. group 2 grades are effective in contexts involving intermittent contact with water, in non-severe conditions. group 3 grades are suitable for similar contexts to those appropriate for group 2 grades, but are easier to weld. group 4 ferritics are more corrosion resistant than type 304 and are suitable for a wide variety of uses. group 5 includes, for example, grades with a very high chromium content of around 29% cr, plus 4% Mo, which makes them as corrosion resistant in seawater as titanium metal. “Nickel plays no role in resistance to pitting corrosion.” Storage tank, in grade 444, Brazil. <strong>The</strong> pre FacTor the “pre” or pitting resistance equivalent number is a measure of the relative pitting corrosion resistance of a stainless steel grade in a chloride-containing environment. the higher a grade’s pre value, the more corrosion resistant that grade will be. 35 30 25 20 15 0 the pre comparison table shows at a glance that for every austenitic grade there is a ferritic grade with comparable corrosion resistance. in the commonly used shortened form of the pre formula pre=%cr+3.3%Mo, molybdenum (Mo) is expressed as being 3.3 times more effective than chromium against pitting corrosion. however, chromium is always essential for providing the basic corrosion resistance. Molybdenum cannot replace this “base” amount of chromium in stainless steels, but can be used to boost corrosion resistance. nickel content is not considered in the formula, since in most applications it plays no role in resistance to pitting corrosion. AustENitiC/fERRitiC PRE CoMPARisoN PREN = %Cr = 3,3 x % Mo + 16 x %N avoIdIng corroSIon Stainless steel’s “passive” layer (see p. 59) needs oxygen to remain intact. an accumulation of deposits can deprive the steel of oxygen at critical points, which could lead to corrosion. propagation of corrosion may lead to eventual rupture of the part. 317lN 446/447 316 304 444 436 430 409 AUSTENITIC FERRITIC 439 SEA wATER 20°C CoASTAl ENv. 20°C PURE wATER Barbecue and trolley, in grade 430, Italy.
CorroSion riSk FACtorS • • • • • • • • embedded particles superficial deposits surface defects structural discontinuities salinity (salty areas, seawater, etc.) increase of temperature highly acidic conditions (strong acids) a strongly “reducing” environment CorroSion-preventing FACtorS • • • • • • • • a clean surface a smooth surface a pre-passivated surface ageing of the surface the washing effect (e.g. rain) higher chromium content oxidising conditions (o 2 – not too strong) adding molybdenum
Page 2 and 3: International Stainless Steel Forum
Page 4 and 5: Structural Steelwork for highway br
Page 6 and 7: Foreword “A Steel whoSe time hAS
Page 8 and 9: the Shining appearance of ferritic
Page 10 and 11: 10 in the Sugar induStry, ferritic
Page 12 and 13: 1 WhaT They’re SayIng abouT FerrI
Page 14 and 15: 1 the 5 feRRitic “faMiLieS” fer
Page 16 and 17: 1 indeed, in many cases, ferritics
Page 18 and 19: 1 peRfection iS MatchinG the Spec i
Page 24 and 25: corrosion sets in when ph reaches a
Page 26 and 27: WhaT They’re SayIng abouT FerrITI
Page 28 and 29: ferritic stainless steels have stre
Page 32 and 33: SucceSSfuL dRawinG MeanS • the ab
Page 34 and 35: lubrIcaTIon good lubrication of the
Page 36 and 37: WhaT They’re SayIng abouT FerrITI
Page 38 and 39: this is especially true of “stabi
Page 40 and 41: 0 Several resistance welding techni
Page 42: adheSive bondinG adhesive bonding c
Page 45 and 46: products and applications Ferritics
Page 47 and 48: uilding & ConStruCtion acceSSorIeS
Page 49 and 50: lIFTS eScalaTor STepS grade SuS 430
Page 51 and 52: home & oFFiCe in the following appl
Page 53 and 54: kITchenWare lIQuId dISpenSer grade
Page 55 and 56: Food proceSSIng WallS & ceIlIngS gr
Page 57: trAnSportAtion buS & coach body Fra
Page 60 and 61: 0 10%-14%cr 14%-18%cr group 1 group
Page 62 and 63: iMpreSSiVe uSe of ferritic welded t
Page 64 and 65: AppendiCeS references bucher, l., p
Page 66 and 67: 66 Appendices List of members Ugine

The Ferritic Solution - Euro Inox

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