ACHIEVEMENTS OF CHEMICAL INDUSTEY DUISBERG. 235 



specimens, photographs, and hT,ntern slides. Just here, however, 

 I must ask you to make one of the hiiidings from the upper air 

 and permit me to deal with the subject at greater length. You 

 will be astonished at the immense progress wliich has been made 

 to the general benefit of our industry. 



Of the greatest interest are the alloys of iron with other heavy 

 metals and metalloids, i. e., alloyed steel. 



Instead of carbon, other elements are emploj^ed, which likewise 

 enhance the hardness of steel, but prevent the formation of a crystal- 

 line micro-structure liable to cracks and flaws. The most important 

 of these elements is nickel. 



Nickel steel. — The readiness with which nickel forms an alloy 

 with iron has long been common knowledge. Even in Bessemer's 

 days attempts were made in Great Britain to turn out cannon 

 made of steel containing 2 per cent nickel. The experiments were 

 not successful because the nickel obtained at that time contained 

 impurities, such as copper, arsenic, and sulphur, so tluU the steel 

 could not be forged. Thirty years later pure nickel, as we know 

 it to-day, made successful results possible. The same was the case 

 with chromium, silicon, and manganese, and not until these elements 

 were produced pure could successful alloys be manufactured with 

 them, either alone or together with nickel. The chief aim in the 

 manufacture of these alloys is the formation of an amorphous, 

 pliable structure of the steel. This result is attained not only by 

 removing more or less of carbon, but above all by a certain thermic 

 treatment, namely, by suddenly cooling steel heated to a high 

 temperature, heating again and keeping it at a certain lower tempera- 

 ture. You will see tv/o samples of steel; in tlie one case, the coarse 

 crystallization of the pure carbon steel before it is forged, and in 

 the other, the same steel refined by the thermic treatment. The 

 difference in the micro-structure of the forged carbon steel and that 

 of the forged and thermically treated nickel steel must also be 

 noted. Whilst carbon stoel after forging still shows a cr3'stalline 

 structure with visible cleavage planes of the crystals, the section of 

 nickel steel displays an amorphous structure closely resembling 

 that of welded iron. For comparison sake, a sample of a welded iron 

 fracture is exhibited. It must not be overlooked, however, that 

 nickel and chrome nickel steels are twice or three times as hard as 

 welded iron. There are also exhibited test pieces of construction 

 parts to be used in the automobile industry made of alloyed steel. 

 Notwithstanding the high tensile strength of about 90 kilos per 

 square niillimet(>r (i. e., about 55 tons per squai-e inch), no fractuie 

 is noticeable, although they arc greatly bent. 



Aside from these improvements, which are of such great moment 

 for structural steel, the iron alloys have found many new applications. 



