著者

嘉村 平八

出版者

社団法人日本鉄鋼協会

雑誌

鐵と鋼 (ISSN:00211575)

巻号頁・発行日

vol.20, no.7, pp.517-521, 1934

---

The specimens of manganese iron which contains up to 3.82% of manganese are made by the melted iron obtained from the sponge iron by hydrogen reduction with the metallic manganese in the market. Ten ingots of different manganese content are forged into the proper shape for the investigation. The measurement of electric conductivity, the mechanical testing and the microscopic investigation on the specimens were carried on as forged, annealed and quenched conditions.<BR>The electric resistivity of the annealed sample increases 0.6 microhm by incrensing 0.1% of Mn and that of the quenched sample is little higher than annealed ones The tensile strength and the elastic limit gradually increase up to 2% Mn, proportionally to the manganese content and over 2%, the ratio of increase is remarkable. In the quenched sample, these increase is marked up to 2% Mn, over 2%, the rate of increase in tensile strength is reduced and the elastic limit decreases suddenly. The elongation and the reduction area decrease exceedingly up to 0.2% Mn, over 0.2% they do not show much decrease by increasing the manganese content and over 2.2% Mn show sudden decrease. In the quenched specimens the rapid decrease of the reduction area is recognized increasing manganese under 0.67% and by increasing more manganese there is not much change in elongation and reduction area. But there is shown sudden decrease from 2.8% to 3.8% Mn in which malleability can hardly be recognized.<BR>The impact value is markedly reduced as the manganese content decreases. Especially in the annealed condition, this phenomenon is more marked, in 0.7% Mn it is 3kg. -meter. Then as the manganese content increases it suddenly goes up and reaches maximum, 13kg. -meter, in 2% Mn. Over this content of manganese it shows sudden decrease and in 3.8% there is almost no value in all conditions.<BR>In the micro-scopic investigation, the structure of low manganese specimens in annealed condition consist all ferrite crystals. When the manganese content increases to about 2% some martensitic structure appears and in 3.8% manganese it changes completely to martensite. In the quenched condition, the martensitic structure appears already in 0.677% manganese and the structure becomes completely martensite in 2% manganese.