On the basis of a mathematical model for sintering process, the effects of operating variables, i. e., temperature and oxygen concentration of gas in ignition furnace, time for ignition, mass velocity of gas, diameter and temperature of solid particles to be fed, mass fraction of coke in a burden materials and voidage of bed, on the temperature distributions in sintering bed are estimated from numerical calculations with the aid of digital computer. Also, theoretical analysis on the optimum pallet speed to obtain a maximum production rate in Dwight-Lloyd sintering process is developed, and the equations on the optimum pallet speed, maximum production rate and mean yield are proposed in terms of the expressions for the definitions of sintering velocity and sintering time.
Synopsis: Effects of arsenic, antimony and tin on strength, recrystallization temperature and Snoek peaks of alpha iron were investigated. It was found that the increase in tensile strength caused by cold drawing became layer in the order, arsenic, tin and antimony addition. Effect of arsenic on the recrystallization temperature of alpha iron was not observed, on the contrary, antimony and tin affected the recrystallization temperature and it rised about 90°C. Changes in tensile strength and in electrical resistivity at liquid nitrogen temperature after aging the alloys quenched from 950°C were also investigated. The changes assumed to be due to precipitation were found in the alloys bearing more than about 0.25 atomic per cent antimony and tin, but were not found in the alloys containing less than 0.045 atomic per cent of antimony and 0.094 atomic per cent of tin, and less than 0.38 atomic per cent of arsenic. The internal friction peaks owing to carbon and nitrogen were investigated by using the alloys containing about 0.25 atomic per cent arsenic, antimony and tin. In addition to the usual carbon and nitrogen peaks, abnormal peaks were observed on high temperature side of the usual peaks. Activation energies of the abnormal peaks were determined as 19.1 kcal/mol in Fe-As-N, 19.2 kcal/mol in Fe-Sb-N, 200 kcal/mol in Fe-As-C, 21.5 kcal/ mol in Fe-As-C, 21.2 kcal/mol in Fe-Sb-C, and 22.5 kcal/mol in Fe-Sn-C.
In order to evaluate the feasibility of Ca-deoxidized steels, machinability tests on variously deoxidized 0.45%C steels are done with carbide tools. The effects of deoxidation on the machinability based on tool life are investigated, and the relationship between oxygen-, aluminum-, calcium-contents in steels and their tool life characteristics is determined. Generally, the higher oxygen content in steel is favorable for the formation of oxide layer on the tool face during cutting various steels. In cutting the steels deoxidized appropriately with Ca, however, the tool wear is found to be considerably suppressed even if their oxygen contents are fairly low. In these cases, very thin oxide layers are observed on tool faces. It seems that the formation of thick oxide layer on tool face is only sufficient condition for good machinability but is not necessary one. Negative correlation is observed between Al content and machinability of Ca-deoxidized steels. It is confirmed that the Ca-deoxidation is applicable to Cr-Mo steels and resulphurized steels for good machinability, too. The results of identifying analysis of oxide layers on tool faces are discussed.