{{refimprove, date=November 2022 Pioneer Zephyr Budd shotweld stainless steel souvenir

Shot welding is a type of spot welding used to join two pieces of

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

together. This is accomplished by

clamping A wheel clamp, also known as wheel boot, parking boot, or Denver boot, is a device that is designed to prevent motor vehicles from being moved. In its most common form, it consists of a clamp that surrounds a vehicle wheel, designed to preven ...

the two pieces together and then passing a large

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...

through them for a short period of time. Shot welding was invented by Earl J. Ragsdale, a

mechanical engineer Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations of ...

at the

Budd Company 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 ...

, in 1932 to weld

stainless steel Stainless steel is an alloy of iron that is resistant to rusting and corrosion. It contains at least 11% chromium and may contain elements such as carbon, other nonmetals and metals to obtain other desired properties. Stainless steel's corros ...

. This welding method was used to construct the ''

Pioneer Zephyr 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 streaml ...

''.

Method

The E. G. Budd Company of

Philadelphia Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Sinc ...

recognized the important

metallurgical Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sc ...

characteristics of

18/8 stainless steel SAE 304 stainless steel is the most common stainless steel. The steel contains both chromium (between 18% and 20%) and nickel (between 8% and 10.5%) metals as the main non-iron constituents. It is an austenitic stainless steel. It is less elec ...

(known today as SAE 304 austenitic stainless steel) and developed a spot welding process to take advantage of the oxidized layer on the surface of stainless steel. Heat treating the 18-8 stainless steel leaves the metal with non-magnetic and

ductile Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...

properties. Repeatedly reheating the metal to 1000–1100°C impairs the mechanical and chemical properties of the metal. The metal becomes susceptible to

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...

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. The

corona Corona (from the Latin for 'crown') most commonly refers to: * Stellar corona, the outer atmosphere of the Sun or another star * Corona (beer), a Mexican beer * Corona, informal term for the coronavirus SARS-CoV-2, which causes the COVID-19 di ...

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 In engineering, shear strength is the strength of a material or component against the type of yield or structural failure when the material or component fails in shear. A shear load is a force that tends to produce a sliding failure on a materia ...

of a

rivet 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 to the head is called the ''tail''. On installation, the rivet is placed in a punched ...

of similar diameter and can be placed 50% closer together. When done properly,

distortion In signal processing, distortion is the alteration of the original shape (or other characteristic) of a signal. In communications and electronics it means the alteration of the waveform of an information-bearing signal, such as an audio signal ...

, which is a problem in fusion welding processes, is eliminated.

References

* Ragsdale, Earl J. W., (August 20, 1932),
Patent number 1,944,106 - Method and product of electric welding
' (

PDF Portable Document Format (PDF), standardized as ISO 32000, is a file format developed by Adobe in 1992 to present documents, including text formatting and images, in a manner independent of application software, hardware, and operating systems. ...

). Retrieved February 27, 2005. * ''Shot Welding - A Forward Step in Resistance Welding'', The Welding Engineer, 17 (8), August 1932, p. 25-26. * Morton C. Walling
''Stitching Steel Into Streamliners - Budd’s new assembly line rolls out cars like cans.''
Popular Science, February 1947, p. 121-127 (archive link). Welding Budd Company