Monel is a high-nickel nickel-copper alloy that was developed in 1905 by Robert Crooks Stanley, a metallurgist at the International Nickel Company (Inco), and patented by the company in 1906. It was named after Ambrose Monell, who was then Inco president; the second L was dropped because family names were not allowed as trademarks. 

Although Monel had been available since 1905, it was the economic disruption that followed the First World War that prompted Inco to pursue the active market development in the 1920s that increased its use. 

Some of Monel’s key advantages were its exceptional corrosion resistance, mechanical strength and hardness, which helped it to find many new industrial and commercial applications. At the inaugural CIM Expo in March 1926, Inco showcased a range of its products, including Monel, and highlighted its applications to attendees. 

“Certainly it has now taken its place as a necessary engineering material for applications requiring an alloy resistant to corrosion,” wrote Paul D. Merica (CIM Bulletin, 1926). 

During the war, there had been a high demand for nickel for military applications. However, when the war ended, so did this market for nickel, wrote K.H.J. Clarke (CIM Bulletin, February 1960). “For 12 months in the immediate post-war period, operations were completely suspended at Inco’s mines and plants because of lack of markets,” he wrote. 

Merica (1926) noted that the plunge in the nickel market “hastened the realization, within the industry, that more active effort must in the future be put into the development and maintenance of the market for nickel if the industry were to become stabilized in the future and less subject to such a catastrophe as that through which it had just gone.” In addition to producing nickel, “the marketing and distribution of nickel must receive equal attention,” he wrote. 

Early in 1922, Stanley became Inco’s new president and began a program to develop the market for nickel in two ways: to develop further the uses of nickel already established, and to develop new uses for nickel and its alloys. “Such an effort had to be and was organized on a broad scale to include active sales and advertising work, as well as research and engineering development,” added Merica. 

From 1905 to 1922, ingots of Monel were produced at Inco’s Orford Works in Bayonne, New Jersey. These ingots were then converted into rods and sheets at external steel plants, according to Merica. 

“After the war, when the newer market development programme was initiated, it was realized that in order to develop the commercial use of this metal to the utmost it would be necessary for The International Nickel Company to undertake also the rolling of the metal,” he wrote. “This was done in order to bring all the operations of its production under one management and in closer contact with those of its distribution.” 

The company chose a site in Huntington, West Virginia to build a new rolling mill devoted exclusively to the production of Monel from the nickel matte exported from Inco’s Copper Cliff mine in Sudbury, Ontario. 

“The success of the double undertaking of market development and of the mill operations at Huntington is best indicated by the fact that since the opening of this plant in June 1922, and the institution of an active distributing campaign, the consumption of Monel metal has increased from about 3,000 [short] tons per annum in 1922, to about 7,500 [short] tons per annum in 1925, thus increasing considerably the production tonnage for the Canadian plants,” wrote Merica, (1926). 

The new rolling mill also helped to solve one of the fabrication challenges that had been an early hurdle to the wider adoption of Monel; Merica noted that it had been considered “very difficult” to weld.  

“When Monel metal was younger, one of the principal cares concerning it was how to fabricate it—to weld it, machine it, braze it, draw and stamp it,” he wrote. “As a consequence of the expenditure of a great deal of laboratory and practical research effort, these problems have now largely been solved and the usual fabricating operations can now be carried out with this metal using the methods—in many cases special—developed by The International Nickel Company, and described by it in special instruction pamphlets issued for the purpose.” 

Merica wrote that it was now possible to make welds in Monel metal plate “possessing 60,000 lbs. per sq. in. tensile strength and 25 per cent elongation, which are equal or even superior in strength and ductility to those made currently in steel, considered to be the most readily welded of materials.” 

According to Stanley (CIM Bulletin, 1927), the new rolling mill enhanced Monel’s quality. “The improved quality of the product in malleability, conformity to engineering standards and in finish, has opened the way to Monel metal in many fields of use,” he wrote. 

Merica (1926) emphasized an important recent development—Monel’s use in the “semi-chemical” fields, in which its corrosion resistance, appearance and the appearance of the products handled in it were of primary importance. “Thus it has become almost standard in the construction of laundry machines, replacing wood, brass and galvanized iron because it can be more readily cleaned and kept clean, and does not spot or discolour the clothing,” he wrote. 

For similar reasons, Monel began to replace wood in textile dyeing equipment. “The dyeing solutions can be completely removed from a Monel metal machine and their colours are not appreciably affected by contact with it,” explained Merica. “These dye solutions are absorbed by wood and necessitate the use of several wood-lined machines when handling different dyes. With Monel metal, one machine can do the work of several wooden ones and as evidence of the standardization of Monel metal in that industry, manufacturers of dyes are now testing their dyes in Monel metal equipment.” 

Merica added that Monel’s use in the food preparation and handling industries was also widespread, such as “in the packing houses and particularly in hotel and restaurant kitchens and in cafeterias, where it is used both for food-containers and for furniture trim, table-tops, cabinets, sinks and other appliances. Again, the appearance and cleanliness of the metal and the fact that it does not contaminate food products are the determining features of its use. In the similar field of hospital utensils Monel metal is also rapidly gaining favour.” 

He recorded a more recent development—its use in soda fountains for ice cream cabinets and for domestic refrigerators. “It is claimed by the producers of such equipment that the metal can be cleaned with half the time and expense required by other metals and in addition it is harder, does not scratch or dent and its appearance is more stable.” 

Other applications of Monel highlighted by Stanley (1927) included shaker screens, jig liners, pumps and valves for the mining industry; equipment for handling steel in pickling solutions, such as tanks and crates; and general uses such as building roofing and hardware, automobile carburetor needles, spark plugs, photographic darkroom equipment, marine hardware and fittings, propellers, cable and shafting. “Wherever a corrosion-resistant material of good appearance and good mechanical properties is needed, Monel metal is used,” he wrote. 

By 1929, according to Clarke (1960), “more nickel was being used annually in peaceful pursuits than during the peak of wartime production.” 

The adoption of Monel was not without some setbacks, however. J.L. Bowlby (CIM Bulletin, 1934) quoted C.E. MacDonald’s discussion of “the case of a New Yorker who had built a yacht which was plated with Monel metal. In a comparatively short while, the plates just simply dropped off. They had been fastened with iron rivets and, as Monel metal and iron in seawater make a very good battery, corrosion of the iron was rapid and the rivets had disappeared.” 

In addition, by the 1930s, Monel was starting to face competition from the emergence of alternative materials—particularly stainless steel, which could be used for many of the same applications and was more cost effective.  

For example, Mark W. Booth (CIM Bulletin, 1944) mentioned that Monel pump shafts were first used in 1920 at the Dominion Coal Company’s collieries in Cape Breton, Nova Scotia. “They were a marked improvement over the ordinary steel shaft for acid resisting, but not mechanically, as the packing would not run very well on them,” he wrote. “Later, since the stainless steel shafts have been developed, they have been used exclusively, except in Sulzer pumps, in which the shaft is completely covered by a sleeve, so that ordinary steel is sufficient.” 

The aerospace industry began to use Monel in the 1950s. “When aircraft fly at supersonic speeds the heat generated by the frictional effects of the atmosphere is so great that the entire wings and fuselage have to be made of extremely heat-resistant alloys,” wrote Clarke (1960). “The first really high-speed aircraft, the Bell X-2, was built principally of Inco’s “K” Monel age-hardenable nickel-copper alloy.” 

Monel is still used in other specialist applications, such as in marine engineering and chemical processing, due to its exceptional resistance to corrosion from seawater and acids, respectively.