Kynal

Kynal was a brand name for a series of aluminium alloys developed and originally produced by the British chemical manufacturer Imperial Chemical Industries (ICI).^[1] The name was derived from Kynoch, an existing ICI trademark for ammunition, and aluminium. It was largely used as substitute for Alclad, a popular corrosion-resistant aluminium alloy.

ICI produced Kynal in quantity at a facility in Waunarlwydd, outside Swansea. The material was extensively used by the British aviation industry during the Second World War, being recognised as a strategic resource. Numerous variations upon the material were devised by ICI around this time. During the 1950s, British Railways became a key consumer of Kynal, using the material on numerous members of its new fleet of diesel traction, including the first generation diesel multiple units (DMUs). By the twenty-first century, the material was largely considered to be obsolete, while the Waunarlwydd chemical works was permanently closed during the 2000s.

History

A key facility involved in the production of Kynal was the Ministry of Aircraft Production's factory at Waunarlwydd,^[2] near Swansea. ICI built and operated the plant on the government's behalf.^[3] Functionally, Kynal was similar to, and could be a substitute for, Alclad.^[4] Applications included various forged items, including pipework, vessels, and heat exchangers, as well as fuselage elements of aircraft.^[5][6] By 1938, the material was being producing at a very high volume as a consequence of the European powers having entered a period of rearmament around the time of Munich crisis, which led into the Second World War.^[7]

During the postwar era, Kynal continued to hold its strategic importance.^[8] The material proliferated throughout British engineering throughout the 1950s and 1960s; it began to be used in the frames of road vehicles during the mid 1950s.^[9] Kynal was used extensively for British Railways' modernisation of the 1950s, specifically in the construction of the publicly-owned organisation's new diesel fleet.^[10] The majority of the 'lightweight' diesel multiple units (DMUs) featured the material.^[11] Around the same era, the company was also involved in studies into the use of Kynal as a roofing material.^[12]

By the twenty-first century, Kynal was largely considered to be obsolete as a material.^[13] During the 2000s, the original Waunarlwydd plant, which was by then owned by Alcoa, was closed down.^[14][15] Despite this, research efforts into fields such as battery technology have involved the use of Kynal.^[16]

Table

	Al	Cu	Mg	Si	Mn	Ni	Zn	Others
	%
Kynal P5	≥99.5								Pure aluminium [17]
Kynal P10	≥99
	Aluminium–silicon alloys
Kynal PA15				12					Brazing wire [18][19]
Kynal PA16				5
Kynal PA17				5
	Aluminium–manganese alloys
Kynal PA19					1.25				[20]
	Aluminium–magnesium alloys
Kynal M35/1			2						[21]
Kynal M35/2			3
Kynal M36			5
Kynal M37			7
	Aluminium–magnesium–silicon alloys
Kynal M39/1			0.7	0.5					[22]
Kynal M39/2			0.7	1
	Aluminium–copper alloys
Kynal 90		2.2	0.3						[23]
Kynal C65		4	0.6		0.5				[23]
Kynal C66		4.4	0.6	0.7	0.6
Kynal C67		4.4	0.6	0.7	0.6
Kynal C69		1	1						[22]
	Nickel–aluminium alloys
Kynal Y88		2.6	1	1		1		0.1% Ti	[23]
Kynal Y92		4	1.5			2
	Aluminium–zinc alloys
Kynal Z93		0.4	2.7				5.3		[24]
Kynal-Core C65A									Pure aluminium-clad forms of the corresponding alloys [25]
Kynal-Core C66A
Kynal-Core C67A
Kynal-Core C68A
Kynal-Core Z93A

See also

• Kycube, a similarly named series of copper beryllium alloys produced by IMI.