Shot welding

Last updated
Stainless steel "business card" with a metal strip showing the Pioneer Zephyr train attached by two shot welds, undetectable on the reverse side Pioneer Zephyr Budd shotweld stainless steel souvenir.gif
Stainless steel "business card" with a metal strip showing the Pioneer Zephyr train attached by two shot welds, undetectable on the reverse side

Shot welding is a type of electric resistance welding which, like spot welding, is used to join two pieces of metal together. The distinguishing feature is that in shot welding, strips and sheets of metal (usually stainless steel) are "sewed" together with rows of uniform spot welds. [1] The weld is achieved by clamping the two pieces together then passing a large electric current through them for a short period of time. Shot welding was patented by Earl J. Ragsdale, a mechanical engineer at the Edward G. Budd Manufacturing Company in 1932 to weld stainless steel. This welding method was used to construct the first stainless steel train, Pioneer Zephyr , in 1934, [1] and became the standard construction technology for railroad passenger cars thereafter.

Method

In the early 20th century, the Edward G. Budd Manufacturing Company had been innovative in the field of sheet metal fabrication, and had revolutionized the construction of automotive bodies in steel during the 1920s. Edward Budd and his employees, notably Earl Ragsdale, recognized the important metallurgical characteristics of 18/8 stainless steel (known today as SAE 304 austenitic stainless steel) and further developed a spot welding process to take advantage of the oxidized layer on the surface of stainless steel. [2] Heat treating the 18-8 stainless steel leaves the metal with non-magnetic and ductile properties. Repeatedly reheating the metal to 1000–1100°C impairs the mechanical and chemical properties of the metal. The metal becomes susceptible to corrosion due to carbide precipitation, and loses fatigue resistance. The important factor in controlling the metal's properties is the dwell time at those temperatures. Using a controlled time element and recorder, a power supply with smooth current, and very brief high currents, a satisfactory spot weld may be produced.[ citation needed ]

The corona of the shot weld should not exist on the metal, and the equipment used produces satisfactory welds with a smaller than normal diameter. Sufficient electrode force is applied to hold the two sheets of metal together and the peak current rapidly creates a forge weld at the interface between the two sheets, producing a small nugget of weld metal, which when cooled results in a shear-resistant metal interface. Good shotwelds have twice the shear strength of a rivet of similar diameter and can be placed 50% closer together. When done properly, distortion, which is a problem in fusion welding processes, is eliminated.[ citation needed ]

Related Research Articles

<span class="mw-page-title-main">Stainless steel</span> Steel alloy resistant to corrosion

Stainless steel, also known as inox, corrosion-resistant steel (CRES) and rustless steel, is an alloy of iron that is resistant to rusting and corrosion. It contains at least 10.5% chromium and usually nickel, and may also contain other elements, such as carbon, to obtain the desired properties. Stainless steel's resistance to corrosion results from the chromium, which forms a passive film that can protect the material and self-heal in the presence of oxygen.

<span class="mw-page-title-main">Welding</span> Fabrication or sculptural process for joining materials

Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as brazing and soldering, which do not melt the base metal.

<span class="mw-page-title-main">Spot welding</span> Process in which contacting metal surfaces are joined by heat from resistance to electric current

Spot welding is a type of electric resistance welding used to weld various sheet metal products, through a process in which contacting metal surface points are joined by the heat obtained from resistance to electric current.

<span class="mw-page-title-main">Rebar</span> Steel reinforcement

Rebar, known when massed as reinforcing steel or reinforcement steel, is a steel bar used as a tension device in reinforced concrete and reinforced masonry structures to strengthen and aid the concrete under tension. Concrete is strong under compression, but has low tensile strength. Rebar significantly increases the tensile strength of the structure. Rebar's surface features a continuous series of ribs, lugs or indentations to promote a better bond with the concrete and reduce the risk of slippage.

<span class="mw-page-title-main">Submerged arc welding</span> Joining metals using electricity, beneath a granulated flux material

Submerged arc welding (SAW) is a common arc welding process. The first SAW patent was taken out in 1935. The process requires a continuously fed consumable solid or tubular electrode. The molten weld and the arc zone are protected from atmospheric contamination by being "submerged" under a blanket of granular fusible flux consisting of lime, silica, manganese oxide, calcium fluoride, and other compounds. When molten, the flux becomes conductive, and provides a current path between the electrode and the work. This thick layer of flux completely covers the molten metal thus preventing spatter and sparks as well as suppressing the intense ultraviolet radiation and fumes that are a part of the shielded metal arc welding (SMAW) process.

<span class="mw-page-title-main">Rivet</span> Permanent mechanical fastener

A rivet is a permanent mechanical fastener. Before being installed, a rivet consists of a smooth cylindrical shaft with a head on one end. The end opposite the head is called the tail. On installation, the deformed end is called the shop head or buck-tail.

<span class="mw-page-title-main">Ultrasonic welding</span> Welding process

Ultrasonic welding is an industrial process whereby high-frequency ultrasonic acoustic vibrations are locally applied to work pieces being held together under pressure to create a solid-state weld. It is commonly used for plastics and metals, and especially for joining dissimilar materials. In ultrasonic welding, there are no connective bolts, nails, soldering materials, or adhesives necessary to bind the materials together. When used to join metals, the temperature stays well below the melting point of the involved materials, preventing any unwanted properties which may arise from high temperature exposure of the metal.

<span class="mw-page-title-main">Monel</span> Solid-solution binary alloy of nickel and copper

Monel is a group of alloys of nickel and copper, with small amounts of iron, manganese, carbon, and silicon. Monel is not a cupronickel alloy because it has less than 60% copper.

<span class="mw-page-title-main">Budd Company</span> United States historic place

The Budd Company was a 20th-century metal fabricator, a major supplier of body components to the automobile industry, and a manufacturer of stainless steel passenger rail cars, airframes, missile and space vehicles, and various defense products.

Friction welding (FWR) is a solid-state welding and bonding process that generates heat through mechanical friction between workpieces in relative motion to one another. This process is used with the addition of a lateral force called "upset" to plastically displace and fuse the materials. Friction welding is a solid-state welding technique similar to forge welding, instead of a fusion welding process. Friction welding is used with metals and thermoplastics in a wide variety of aviation and automotive applications.

<span class="mw-page-title-main">Gas tungsten arc welding</span> Welding process

Gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG) welding, is an arc welding process that uses a non-consumable tungsten electrode to produce the weld. The weld area and electrode are protected from oxidation or other atmospheric contamination by an inert shielding gas. A filler metal is normally used, though some welds, known as 'autogenous welds', or 'fusion welds' do not require it. When helium is used, this is known as heliarc welding. A constant-current welding power supply produces electrical energy, which is conducted across the arc through a column of highly ionized gas and metal vapors known as a plasma. TIG welding is most commonly used to weld thin sections of stainless steel and non-ferrous metals such as aluminum, magnesium, and copper alloys. The process grants the operator greater control over the weld than competing processes such as shielded metal arc welding and gas metal arc welding, allowing stronger, higher-quality welds. However, TIG welding is comparatively more complex and difficult to master, and furthermore, it is significantly slower than most other welding techniques. A related process, plasma arc welding, uses a slightly different welding torch to create a more focused welding arc and as a result is often automated.

<span class="mw-page-title-main">Sheet metal</span> Metal formed into thin, flat pieces

Sheet metal is metal formed into thin, flat pieces, usually by an industrial process.

Electric resistance welding (ERW) is a welding process in which metal parts in contact are permanently joined by heating them with an electric current, melting the metal at the joint. Electric resistance welding is widely used, for example, in manufacture of steel pipe and in assembly of bodies for automobiles. The electric current can be supplied to electrodes that also apply clamping pressure, or may be induced by an external magnetic field. The electric resistance welding process can be further classified by the geometry of the weld and the method of applying pressure to the joint: spot welding, seam welding, flash welding, projection welding, for example. Some factors influencing heat or welding temperatures are the proportions of the workpieces, the metal coating or the lack of coating, the electrode materials, electrode geometry, electrode pressing force, electric current and length of welding time. Small pools of molten metal are formed at the point of most electrical resistance as an electric current is passed through the metal. In general, resistance welding methods are efficient and cause little pollution, but their applications are limited to relatively thin materials.

<i>Pioneer Zephyr</i> American train

The Pioneer Zephyr is a diesel-powered trainset built by the Budd Company in 1934 for the Chicago, Burlington & Quincy Railroad (CB&Q), commonly known as the Burlington Route. The trainset was the second internal combustion-powered streamliner built for mainline service in the United States, the first such train powered by a diesel engine, and the first to enter revenue service.

The weldability, also known as joinability, of a material refers to its ability to be welded. Many metals and thermoplastics can be welded, but some are easier to weld than others. A material's weldability is used to determine the welding process and to compare the final weld quality to other materials.

<span class="mw-page-title-main">Honeycomb structure</span> Natural or man-made structures that have the geometry of a honeycomb

Honeycomb structures are natural or man-made structures that have the geometry of a honeycomb to allow the minimization of the amount of used material to reach minimal weight and minimal material cost. The geometry of honeycomb structures can vary widely but the common feature of all such structures is an array of hollow cells formed between thin vertical walls. The cells are often columnar and hexagonal in shape. A honeycomb shaped structure provides a material with minimal density and relative high out-of-plane compression properties and out-of-plane shear properties.

<span class="mw-page-title-main">Flash welding</span> Type of resistance welding that does not use any filler metals

Flash welding is a type of resistance welding that does not use any filler metals. The pieces of metal to be welded are set apart at a predetermined distance based on material thickness, material composition, and desired properties of the finished weld. Current is applied to the metal, and the gap between the two pieces creates resistance and produces the arc required to melt the metal. Once the pieces of metal reach the proper temperature, they are pressed together, effectively forge welding them together.

<span class="mw-page-title-main">Tube (fluid conveyance)</span>

A tube, or tubing, is a long hollow cylinder used for moving fluids or to protect electrical or optical cables and wires.

<span class="mw-page-title-main">Metal hose</span>

A metal hose is a flexible metal line element. There are two basic types of metal hose that differ in their design and application: stripwound hoses and corrugated hoses.

In metallurgy, peening is the process of working a metal's surface to improve its material properties, usually by mechanical means, such as hammer blows, by blasting with shot, focusing light, or in recent years, with water column impacts and cavitation jets. With the notable exception of laser peening, peening is normally a cold work process tending to expand the surface of the cold metal, thus inducing compressive stresses or relieving tensile stresses already present. It can also encourage strain hardening of the surface metal.

References

  1. 1 2 Walling, Morton C. (February 1947). "Stitching steel into streamliners". Popular Mechanix . Archived from the original on 5 December 2019. Retrieved 9 January 2024.
  2. "Jan 16, 1934. E.J.W. Ragsdale: Method and product of electric welding". Google Patents. August 20, 1932. Retrieved 9 January 2024.