Number I1 September 1952

U"eldiny Research Council Bulletin Series

Weldlllg Processes and Procedures Employed ill Jolititig Stainless Steels

by Helmut Thielseh

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Welding Processes and Procedures Employed in Joining Stainless Steels

0 A review of published and unpublished information on metal-arc weld- ing, -, gas welding, resistance welding and cut- ting. Discussion of welding characteristics and procedures, preparation of base steel, jigs and fixtures, welding technique, defects in welded joints, cleaning of welded joints, mechanical properties and applications

by Helmut Thielsch Inert-Gas Carbon- and -Arc Welding This process is widely used for welding stainless-steel sheets up to about 1/8 in. in thickness—although thicknesses up to 1/2 in. Summary have been satisfactorily welded . Up to a sheet thickness of about 6 /32-in. butt-type joints without a root opening are recommended. Whereas generally is not used for Shielded-Metal-Arc Welding thickness of less than 1/16 in ., it is recommended above 1/16 in. Edge Preparation . Sheets and plates between and This process is generally used to weld sheets 6/32 1/4 in. may have either square butt-type joints or single 70-deg V joints thicker than 1 /32 in. Edge Preparation. Square butt type joints are used up to with a root opening of about 1/16 in . A double-V joint with a 3 /32-in . root opening is generally preferred when welding plates 3/16 in. From 3 /16 to 1/2 in . a single 70-deg V groove is preferred heavier than 1/4 in. with a 1 /16-in . root face and a 1/32- to 1/16-in. root opening. A single-U joint is recommended for plates between 1/2 and 3 /4 in. From 3 /4 in . and up, double 60-deg V or U joints are gen- Inert-Gas-Shielded Welding with Consumable erally preferred. This process is used for plate thicknesses up to 1 in . by employ- ing a two-pass procedure and a straight butt preparation . Heav- Submerged-Arc Welding ier sections are also satisfactorily welded by means of suitable joint preparation. This process is often used when semiautomatic and automatic welding is advisable on plates of medium and heavy thicknesses. Oxyacetylene Welding Edge Preparation. Square butt-type joints are generally recommended for plates up to 3/16 in . thick . For single-pass This process is primarily used for sheets up to a thickness of welding of plates between 3/16 and 3/8 in . a single 60-deg V groove about 0 .0375 in . Because of the development of the inert-gas is preferred . Above 1/2 in . a 45-deg V groove has been recom- and atomic- welding processes, the oxyacetylene process mended . When double-pass welding is used on plates heavier is being more and more replaced by the other processes. than 3/8 in . a double-V joint is preferred having a 90-deg groove Edge Preparation is essentially the same used for atomic-hydro- angle. gen welding.

Resistance Welding Atomic-Hydrogen Welding Stainless-steel sheets are readily joined by any of the major This process is used in the fabrication of light-gage sheet ma- resistance welding processes including spot, seam, projection and terials—varying from about 0.010 in. to about 1/8 in. . Advantages of these processes are in the welding Edge Preparation . On thin sheets up to a thickness of about speed possible and the localized application of heat which 0.0375 in . the edges are usually turned up to thickness equal that minimizes distortion and harmful chromium-carbide precipitation. of the sheet . A root opening is not used. Between 0 .0375 and Proper fusion of the joints depends upon eight major factors: 1 /16-in. square butt-type joints are preferred with no root open- (1) thermal and electrical conductivity of work, (2) geometry of ing. Single-V joints are generally recommended for thicknesses parts to be joined, (3) thermal and electrical conductivity of elec- between 1 /1s and 1/4 in . Above 1/4 in . a double-V joint seems to trodes, (4) geometry of electrodes, (5) pressure, (6) elec- represent preferred practice. trode voltage and current, (7) weld time and "hold" time and (8) cleanness of surfaces to be joined. Helmut Thielsch is Technical Assistant, Welding Research Council, New York 18, N . Y. Jigs and Fixtures This report was prepared under the auspices of the Literature Advisory Committee of the Welding Research Council : G. E. Doan, Chairman; T . S. Fuller, L . E. Grinter, C . E . Jackson, E. M . MacCutcheon, R. F. Miller, W. The distortion caused by welding is more severe on austenitic Spraragen, David Swan, R . D . Thomas, Jr ., J . L. Walmsley and H. Thielsch, Secretary . stainless steels than on mild steels, because the austenitic stain-

Thielsch—Stainless Steel W eldina 1