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The austenitic steel with designation 1.4404 contains molybdenum in addition to chromium and nickel. The difference against 1.4301/1.4307 apart from the presence of molybdenum is that the nickel content is greater. This type of stainless steel is often referred to as acid resistant which is to some degree a misnomer since the material resists attack only by weak acids. 1.4404 has low carbon content which means that it can be welded without risking impairment of corrosion resistance in the vicinity of the weld. In terms of strength, 1.4404 is more or less equivalent to the lower alloyed grades 1.4301/1.4307.
Flat bars of stainless steel of lesser thickness are difficult to roll and it is usually more efficient to convert hot-rolled strip to bar format via slitting. As hot-finished plate, grade 1.4404 is standardised in EN 10088-2. Tibnor’s programme of stainless flat bars based upon slitting from plate covers the range 3-12 mm thickness with widths up to and including 150 mm.
The presence of molybdenum along with chromium renders 1.4404 resistant to corrosion in weak acids and water containing chlorides so long as the chloride concentration is not too high; an example of an environment where the steel works well is salt-laden coastal atmosphere.
The formability of flat bars of 1.4404, even when manufactured by slitting of strip, is in most cold-forming operations excellent and often better than hot-rolled carbon steel. The steel is also characterised by very good weldability and it seldom gives rise to any problems in fabrication of welded structures. Machining, on the other hand, can pose difficulties but is facilitated via use of bespoke tooling.
The hot-finished sheet in 1.4404 used as starting material for slitting of flat bars has surface finish 1D (annealed and with surface oxide removed by pickling) and so the wide face of the bars has the same finish. The side faces have a typical slit appearance and small burrs can be encountered. Thickness and width have plus/minus tolerances as defined in EN 10058. Straightness expressed as height of arc is at most 0.004 times the bar length.