Stainless Steel Flat Bar Annealed and Pickled EN 1.4404
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.
Thicker flat bars of stainless steel are manufactured by hot rolling. In flat-bar format, grade 1.4404 is standardised in EN 10088-3. Tibnor’s programme of hot-finished stainless flat bars covers the range 10-45 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 hot-finished flat bars in grade 1.4404 is in most cold-forming operations excellent and often better than hot-rolled carbon steel. The material is also characterised by very good weldability and 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.
Hot-finished flats in grade 1.4404 have surface finish 1D as defined in EN 10088-3 (annealed and with surface oxide removed by pickling). 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.