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ISO 3581-2016 pdf free download
ISO 3581-2016 pdf free download.Welding consumables — Covered electrodes for manual metal arc welding of stainless and heat-resisting steels — Classification
Produits consommubies pour le soudaqe — Electrodes enrobées pour le soudage manuel a lurc des aciers inoxydables et resistant aux tern pératures élevées — Classification.
oxidizing materials in the coating or the increase of carbon from CO2. Very high heat input can also have an effect, especially with duplex steels. When the ferrite content in undiluted weld metal is found to be significantly different from that quoted in the manufacturer’s certification, one or more of the above factors are most likely to be the cause of the difference.
B.6 Effect of heat treatment
Stainless steel base metals are generally supplied in the solution annealed and quenched condition. In contrast, most welded joints are put into service in the as-welded condition. In some cases, however, a postweld heat treatment can, or should, be applied. This can reduce the magnetically determined FN to some extent, even to zero. The effects of heat treatment on mechanical and corrosion properties can be significant, but are beyond the scope of this brief discussion.
B.7 Determination of ferrite content
B.7.1 The several parties concerned with the integrity of a stainless steel weldment should all be able to agree upon the ferrite content. These parties could include the manufacturer of the filler material, the fabricator of the weldment, a code or regulatory body, and an insurance company. It is therefore essential that the method for the determination of ferrite be reproducible. Early observations of ferrite in stainless steel weld metals were largely by metallography. Depending on the etchant, either the ferrite or the austenite is preferentially attacked, distinguishing the ferrite from the austenite matrix. Unfortunately, the ferrite phase is extremely fine and very irregular in shape, and is also not uniformly distributed In the matrix. The reliability and reproducibility of this method of estimation was poor. In addition, metallographic examination is a destructive test, which is not suitable for in-process quality assurance monitoring.
B.7.2 As ferrite Is ferromagnetic, it is easily distinguishable from austenite. The magnetic response of an otherwise austenitic weld metal is approximately proportional to the amount of ferrite present. The magnetic response is also affected by the composition of the ferrite (a more highly alloyed ferrite will have a smaller magnetic response than an equivalent amount of lower alloyed ferrite). This property can therefore be used for ferrite determination if it is possible to establish a calibration procedure for magnetic instruments.
Of course, it would have been desirable to establish a magnetic calibration procedure in such a fashion that the results would be directly convertible into “percent ferrite”. However, because of the composition effect noted above and because agreement on the true “percent ferrite” proved to be impossible to achieve, an arbitrary ‘Ferrite Number” scale was adopted. The Ferrite Number was initially believed to be a reasonable approximation of the percent ferrite in a 19 9 or type 308 weld metal, but later studies indicate that EN appreciably overstates the “percent lerrite” in a weld metal, From a practical standpoint, this is unimportant. ISO 3581-2016 pdf free download.
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