Tag Archive for Tag: Welding

Tag: Welding Resistance Welding of Cold-Formed Steel

Resistance welding comprises a group of welding processes wherein coalescence is produced by the heat obtained from resistance of the work to flow of electric current in a circuit of which the work is part and by the application of pressure. Because of the size of the equipment required, resistance welding is essentially a shop process. Speed and low cost are factors favoring

View Article...

Tag: Welding Welding and Brazing of Aluminum

Weldability and brazing properties of aluminum alloys depend heavily on their composition and heat treatment. Most of the wrought alloys can be brazed and welded, but sometimes only by special processes. The strength of some alloys  depends on heat treatment after welding. Alloys heat treated and artificially aged are susceptible to loss of strength at the weld, because weld is essentially cast. For this

View Article...

Tag: Welding Welding Ferrous Materials

General welding characteristics of the various types of ferrous metals are as follows: Wrought iron is ideally forged but may be welded by other methods if the base metal is thoroughly fused. Slag melts first and may confuse unwary operators. Low-carbon iron and steels (0.30%C or less) are readily welded and require no preheating or subsequent annealing unless residual stresses are to

View Article...

Tag: Welding Fracture Critical Members

For railway bridges, fracture critical members (FCM) are those members or components of members loaded in tension whose failure would be expected to result in collapse of the bridge, or would prevent the bridge from performing its design function. If the bridge cannot carry the assigned rail traffic, it is considered not performing its design function. Tension components include all portions of tension

View Article...

Tag: Welding Compression Splices

The requirements for strength of splice given in Art. 5.26 for tension splices apply also to compression splices. Compression members may be spliced with complete-penetration groove welds. As for tension splices, with such welds, it is desirable that splice plates not be used. Groove-welded compression splices may be designed for the basic allowable stresses for base metal. Fatigue does not control if

View Article...

Tag: Welding Welding Clearance and Space

Designers and detailers should detail connections to ensure that welders have ample space for positioning and manipulating electrodes and for observing the operation with a protective hood in place. Electrodes may be up to 18 in long and 3⁄8 in in diameter. In addition, adequate space must be provided for deposition of the required size of fillet weld. For example,

View Article...

Tag: Welding Weld Quality

A basic requirement of all welds is thorough fusion of weld and base metal and of successive layers of weld metal. In addition, welds should not be handicapped by craters, undercutting, overlap, porosity, or cracks. (AWS D1.1 and D1.5 give acceptable tolerances for these defects.) If craters, excessive concavity, or undersized welds occur in the effective length of a weld,

View Article...

Tag: Welding Welding Procedures

Welds should be qualified and should be made only by welders, welding operators, and tackers qualified as required in AWS D1.1 for buildings and AWS D1.5 for bridges. Welding should not be permitted under any of the following conditions: When the ambient temperature is below 0F When surfaces are wet or exposed to rain, snow, or high wind. When welders

View Article...

Tag: Welding Welding Materials

Weldable structural steels permissible in buildings and bridges are listed with required electrodes in Tables 5.10 and 5.11. Welding electrodes and fluxes should conform to AWS 5.1, 5.5, 5.17, 5.18, 5.20, 5.23, 5.25, 5.26, 5.28, or 5.29 or applicable provisions of AWS D1.1 or D1.5. Weld metal deposited by electroslag or electrogas welding processes should conform to the requirements of

View Article...

Tag: Welding Effects of Welding

Failures in service rarely, if ever, occur in properly made welds of adequate design. If a fracture occurs, it is initiated at a notchlike defect. Notches occur for various reasons. The toe of a weld may form a natural notch. The weld may contain flaws that act as notches. A welding-arc strike in the base metal may have an embrittling

View Article...