| Show BRITTLE DRILL STEEL george rember of halley hafley idaho who graduates from the mining and metallurgy department of the university of idaho this month has made an important discovery whereby brittleness can be eliminated from drill steel in describing his discovery mr rember says drill steel often becomes brittle after short use in what is known as the hammer type of machine drill the part which becomes brittle and which generally breaks off is the shank end which fits into the drill chucks this brittleness is caused by the repeated impact of the hammer on the end of the drill the treatment depends upon the principle that if a piece of steel be heated to what is known as the temper the grain will be refined the heating should not be carried above the temperature of because the higher the steel is heated above this temperature the larger will be the resulting grain to determine accurately this temperature pera ture a piece of steel like that of which the drills are made is heated to a bright red heat withdrawn from the forge or furnace and placed in a dark room or blackened box and as it cools it is closely watched the cooling will be fairly regular until a certain temperature is reached when the steel brightens suddenly this is the temperature pera ture of and the experiment should be repeated a number of times until this temperature is accurately known to the eyes this temperature should be noted in the dark room or black box and also in the daylight so that there is no mistake about it in case there be any difficulty in determining it it can be gotten in another way take a piece of steel and heat it slowly as above directed and while it is heating try it with a common horseshoe magnet the cold steel will be attracted by the magnet it will be attracted by the magnet during tl the tempering range 41 of temperatures and it will be attracted by the magnet when it is a very dull red it loses its magnetism suddenly at the temperature of re cale sence so this property of magnetism may be used as indicated to determine when the steel has reached the proper tem pera ture tur now having the temperature of recal well in mind the brittle shanks of drills should be heated until they reach keach this temperature the heating should be done carefully as it is not desirable to go much above the but at the same time no result will be obtained if the steel is not brought up to this temperature As soon as he steel has been heated to reach it is withdrawn from the forge or furnace and is either annealed or tempered as desired but the brittleness will be entirely removed |
