The Mackie Process - Revolutionary Development of the Crack Free Rail
By Sydney S. Slaven

Irwin Cameron, {I.C.}, Mackie was a metallurgist employed by the Dominion Steel & Coal Company who solved the problem that had plagued railway travel since its beginning – that of rails cracking, often with disastrous results, under the stress of weight. C. Mackie was a graduate of Dalhousie University who began work with Dosco in 1902 at the Sydney works. He retired 62 years later as the Dosco Director of Metallurgy.

Since the middle of the 19th century, {when steel replaced wooden rails}, railways were tormented by rails that cracked under the pounding of a train’s wheels. These were rails that at the time seemed flawless but, as locomotives carried increasingly larger loads, the problem became more pronounced. Of course this led to sudden, without warning, devastating derailments.

In 1918 laboratory studies discovered the existence of minute cracks deep inside newly manufactured rails. These cracks were hydrogen bubbles which came to be known as “shatter cracks, thermal ruptures and fissures.” Over time the weight of usage caused the rails to snap without warning. However, no cure for the problem was forthcoming at the time although it was agreed that the problem of “shatter cracks” was introduced at some stage of manufacturing.

Metallurgical scientists tested on the assumption that the problem originated from the high temperatures required to roll rails. Tests were conducted unsuccessfully for many years.
Mackie begin his own experiments in 1930 at the Sydney Mill. Because of the lack of success of high temperature experiments he looked in the opposite direction. He discovered that the cracks were occurring in the steel at low temperatures. Therefore, he concluded that the answer should lie in the slowing down or controlling of the cooling process of the red-hot rails.

Extensive testing verified Mackie’s theory and by July, 1931, Sydney Steel was producing the world’s first crack or “shatter” free rails.

Method of Controlled Cooling
{1} Rails allowed to cool naturally on the mill cooling beds until below 900 degrees F.
{2} Before they reach the temp. of 660 degrees F. they are assembled in groups of 4 or 5 rails with the heads turned up.
{3} Then they are lifted by a magnet crane and stowed in large sheet iron boxes. These boxes are 42 feet in length, 5 foot 6 inches wide and 8 feet 6 inches deep. Each box will hold 120 rails of 130 pound per yard section. The different tiers are separated by skid bars.
{4} When a box is filled a cover is placed upon it and the rails are allowed to cool slowly for from 24 to 30 hours, by which time they will have reached a temperature within 100 degrees F. of the surrounding atmosphere.
{5} They are then ready to be discharged and finishing operations performed.

C. Mackie received a Canadian patent on his process and the Canadian National Railroad was the first railway to exclusively use his rails. By 1933, Canada’s other rail mill at Algoma was using his method to produce rails for the Canadian Pacific Railroad. Within a few years most of the world’s major countries were manufacturing the safe rail produced by the Mackie Process.

When Mackie applied for a U. S. patent, Bethlehem Steel began legal action to block the patent. It dragged through the courts for seven years before Bethlehem relented and began paying Mackie royalties. Perhaps Mackie received some consolation from the fact that every rail manufactured in Canada using his process had Mackie stamped on its side.