October 20, 1921} 



NATURE 



249 



the small ones have been obtained from the 

 eutectoid cementite. In the author's first paper 

 it was shown that a large amount of mechanical 

 treatment was needed in order to produce this 

 complete spheroidisation. The macrostructure 

 -hows that the cementite vein runs close up to 

 he edge, and the Oriental maker must have 

 relied most upon securing the best cutting proper- 

 ties in the cementite particles. 



High-speed tool steel, which is an alloy steel 

 containing from i6 to 20 per cent, of tungsten 

 and from 3 to 5 per cent, of chromium, in addi- 

 tion to a carbon content not exceeding 0-75 per 

 cent., together with vanadium up to i per cent., 

 also belongs to the cementitic series of steels, and 

 its structure in the annealed condition is strikingly 

 similar to that of Damascene steel. Spheroidised 

 carbide particles are embedded in a sorbitic 

 matrix. To produce the characteristic high-speed 

 hardness such steels have to be heated to in- 

 cipient melting and then rapidly cooled in a 

 current of air. Even after this treatment a 

 certain amount of carbide remains undissolved, 

 and there are indications that a moderate amount 

 of it increases the cutting properties of the tool. 

 What is important to notice is that the makers of 

 high-speed steel emphasise the necessity of pro- 

 ducing a particular type of structure under the 

 hammer, and that during this operation the 

 massive carbides and tungstides present in the 

 ingot are broken down and uniformly dis- 

 tributed through it. Accordingly the ingots are 

 first hammered into billets, and the latter are re- 

 eated and hammered a second time. This double 

 reatment is indispensable and must precede the 

 eat treatment proper by thoroughly breaking up 

 nd distributing evenly the carbides and tung- 

 - tides throughout the steel. 



Col. Belaiew then compares not only the struc- 

 tures, but also the respective processes of manu- 

 facture, and points out how similar they are. 

 Both start with a cementitic steel ; both require 

 the greatest care in breaking and evenly dis- 

 tributing the carbides under the hammer; in both 

 cases the amount of mechanical work done on a 



given article is ver}- large ; in both Cases the 

 structure of the resulting carbides is globular or 

 spherulitic, while the matrix is martensitic; in 

 both cases the cutting properties of the edge 

 depend both on the matrix and the carbides, and 

 the author is disposed to think that the role of 

 the latter is the more important of the two. His 

 studies in this field have led him to the belief 

 that the workers in Damascene steel, while very 

 strict as regards the hammering temperatures, 

 did not lay anything like so much stress on the 

 subsequent heat treatment. 



In Damascene steel the degree of spheroidisa- 

 tion is always very high. This was not an end in 

 itself, but was attained incidentally by the numer- 

 ous cautious forgings and heatings which were 

 designed to produce the greatest ductility possible. 

 In high-speed tool steels spheroidisation is also 

 attained, but the author holds that insuthcient 

 stress has been laid on this point by both makers 

 and users, and that the scientific application of 

 the spheroidising process would help to improve 

 the qualities of existing steels. He considers also 

 that another inference might be drawn from the 

 Damascene process, namely, the proper study of 

 the macrostructure in all cases. An Oriental 

 maker would never manufacture a steel article 

 without having satisfied himself by studying the 

 "watering" that the distribution of the carbide 

 particles was the best possible and in accordance 

 with the shape and properties of the article- 

 Neither would he find a buyer ready to accept a 

 sword or a tool without a proper metallographic 

 examination of it as a whole, and to this the 

 Oriental watering lent itself well. The author 

 suggests, therefore, that a proper examination of 

 the watering of high-speed steel, whether in billets 

 or in the finished article, should prove useful. It 

 is interesting to notice that he found a certain 

 degree of high-speed hardness in Damascene 

 steel itself. This point would repay investigation, 

 for if confirmed it would prove that, at any rate 

 in certain cases, the use of alloy steels is unneces- 

 sar}-, and that they could be replaced by the 

 cheaper carbon steels. 



Obituary. 



Dr. Julius Hanx. 

 ' I ""HE death of Hann, which was briefly noted in 

 ■*• the issue of Nature for October 13, removes 

 from the meteorological world the most prominent 

 figure of the past generation and the most pro- 

 ductive of all contributors to that branch of 

 science. Hann was born at Schloss Hans, near 

 LLoz, in Austria, on March 23, 1839, and his youth 

 was spent in the Alps at Kirchdorf, in Kremstal, 

 some thirty miles south of Linz. After taking his 

 degree in mathematics and physics, he took up a 

 professional career as teacher of those subjects in 

 the high school of Schottenfeld, \'ienna, and after- 

 wards at Linz. At the age of twenty-nine he 

 was appointed on the staff of the Central Anstalt 

 NO. 2712, VOL. 108] 



fiir Meteorologie at \'ienna, which was then 

 under the direction of Carl Jelinek. He succeeded 

 Jelinek as director in 1874, ^"^ continued in office 

 I until 1897, when, at the age of fifty -eight, he gave 

 i up the appointment and retired to Graz, in Stvria, 

 ' in order to pursue his studies in meteorology ; but, 

 ; finding Graz inconvenient for that purpose, he 

 ! returned to \'ienna in 1900, and thereafter, as 

 ■ professor in the university, he occupied a room in 

 the Central Anstalt on the Hohe ^^'arte, and con- 

 tinued to work there until the end of his life. 



Hann's chief and most continuous occupation was 

 the editing of the Meteorologische Zeitschrift.which, 

 in conjunction with Jelinek, he started on May i, 

 1866, as the Zeitschritt der Oesterreichischen 



