CLASSIFICATION

ísol-309 has nominal composition (wt. %) of 24 Cr, 13 Ni. Filler metals of this classification are commonly used for welding similar alloys in wrought or cast form. Occasionally, it is used to weld Type 304 and similar base metals where severe corrosion conditions exist that require higher alloy weld metal. They are also used in dissimilar metal welds, such as joining Type 304 to carbon steel, welding the clad side of Type 304 clad steels, and applying stainless steel sheet linings to carbon steel shells.

Gas Tungsten Arc Welding: This welding process involves the least change in the chemical composition from wire to deposit, and hence produces the smallest difference between the ferrite content calculated from the wire analysis and that measured on the undiluted deposit. There is some loss of carbon in gas tungsten arc welding – about half of the carbon content above 0.02 percent. Thus, a wire of 0.06 percent carbon will typically produce a deposit of 0.04 percent carbon. There is also some nitrogen pickup – a gain of 0.02 percent. The change in other elements is not significant in the undiluted weld metal.

When welding stainless steels with the gas tungsten arc process, direct current electrode negative (dcen) is preferred. For base metal up to 1.6 mm thick, argon is the preferred shielding gas because there is less tendency to melt through these lighter thicknesses. For greater thicknesses, or for automatic welding, mixtures of helium and argon are recommended because of the greater penetration and better surface appearance. Argon gas for shielding may also be used and will give satisfactory results in most cases, but somewhat higher amperage will be required.

Gas Metal Arc Welding: For this process, typical carbon losses are low, only about one quarter of the gas tungsten arc welding process. However, the typical nitrogen pick up is much higher than in gas tungsten arc welding, and it should be estimated at about 0.04 percent (equivalent to about 3 or 4 FN loss) unless specific measurements on welds for a particular application establish other values. Nitrogen pickup in this process is very dependent upon the welding technique and may go as high as 0.15 percent or more. This may result in little or no ferrite in the weld deposits of filler metals such as ER308 and ER309. Some slight oxidation plus volatilization losses may occur in manganese, silicon, and chromium contents.

When using the gas metal arc welding process in which the filler metal is employed as an electrode, direct current electrode positive (dcep) is most used.

The shielding gas for spray transfer is usually argon, with or without minor additions of oxygen. For short circuiting transfer, shielding gases composed of helium plus additions of oxygen and carbon dioxide are often used.

The minimum thickness that can be welded by spray transfer is approximately 3.2 to 4.8 mm. Short circuiting transfer can be used to weld material as thin as 1.6 mm. However, thinner sections can be joined if a backing is used.

Submerged Arc Welding: Submerged arc welds show variable gains or losses of alloying elements, or both depending on the flux used. All fluxes produce some changes in the chemical composition as the electrode is melted and deposited as weld metal. Some fluxes deliberately add alloying elements such as niobium (columbium) and molybdenum; others are very active in the sense that they deplete significant amounts of certain elements that are readily oxidized, such as chromium. Other fluxes are less active and may contain small amounts of alloys to offset any losses and thereby produce a weld deposit with a chemical composition close to the composition of the electrode. If the flux is active or alloyed, changes in the welding conditions, particularly voltage, will result in significant changes in the chemical composition of the deposit.

Higher voltages produce greater flux/metal interactions and, for example, in the case of an alloy flux, greater alloy pickup. When close control of ferrite content is required, the effects of a particular flux/electrode combination should be evaluated before any production welding is undertaken.

For submerged arc welding, direct current electrode positive (dcep) or alternating current (ac) may be used. Basic or neutral fluxes are generally recommended to minimize silicon pickup and the oxidation of chromium and other elements. When welding with fluxes that are not basic or neutral, electrodes having silicon content below the normal 0.30 percent minimum may be desired for submerged arc welding.

Ferrite Number: The ferrite content of welds may be calculated from the chemical composition of the weld deposit. This can best be done using the WRC-1992 Diagram. The differences between measured and calculated ferrite are somewhat dependent on the ferrite level of the deposit, increasing as the ferrite level increases. The agreement between the calculated and measured ferrite values is also strongly dependent on the quality of the chemical analysis.

Variations in the results of the chemical analyses encountered from laboratory to laboratory can have significant effects on the calculated ferrite value, changing it as much as 4 to 8 FN. Cooling rate has a significant effect on the actual ferrite content and is one reason for the variations between calculated and measured ferrite of weld metal.

CHEMICAL COMPOSITION OF UNDILUTED WELD

Single values are maxima, except where specified otherwise.

Mechanical Properties: The tensile properties, bend ductility, and soundness of welds produced using filler metal that conforms to this specification are frequently determined during welding procedure qualification. For cryogenic applications, impact properties of welds are required. It should be realized that the variables in the process, such as current, voltage, and welding speed; variables in the shielding medium, such as the gas mixture or flux; variables in the manual dexterity of the welder; and variables in the composition of the base metal influence the results that may be obtained. When properly controlled, however, these filler metals will give sound welds under widely varying conditions with tensile strength and ductility like that obtained by the covered arc welding electrodes.

Note that the impact properties of welds made with bare filler metals in the GTAW or GMAW processes are usually superior to those produced with the SMAW or SAW processes.

ELECTRODE SIZES: 0.80, 1.00, 1.20, 1.60, 2.00, 2.40, 3.20, 4.00, 4.80 (Available in GTAW, GMAW & SAW forms)

WARNING: Safety and health information is available from many sources, including, but not limited to Safety and Health Fact Sheets listed in A11.3, ANSI Z49.1 Safety in Welding, Cutting, and Allied Processes published by the American Welding Society, 8669 Doral Blvd., Suite 130, Doral, FL 33166., and applicable federal and state regulations. The Safety and Health Fact Sheets are revised, and additional sheets added periodically.