The process of the formation of ferrite and pearlite in cast iron was investigated. Specimens used for the experiments were pure Fe-C, Fe-C-Si, Fe-C-Si-Mn alloys and commercial charcoal pig iron 40 grs. of each alloy was melted in a Tammann tube in a silit furnace and cooled with a rate of 7∼10°C/min. (furnace cooled) or 2∼5°C/min. (slow cooled) near the eutectoid temperature while the cooling curve was plotted. At any point of the cooling curve between eutectic and eutectoid temperatures the alloy was quenched into cold water and the structure was observed. The alloy quenched at each step of cooling showed the structure developed to the time and which would show the process of the transformation.
  From the experiments mentioned above, the fallowing evidences were observed.
  1) For iron-carbon alloy, the acicular or lump cementites precipitate in austenite matrix along the Acm-line of the iron-carbon diagram while cooling. At the eutectoid temperature, the pearlite is neucleated by the cementites. The acicular cementites appear on the boundaries of flake graphite and austenite, and the lumpy one appears on those of SASANOHA⁶⁾ austenites.
  2) In iron-carbon-silicon (3∼4%Si) alloy, the lump cementites precipitate on the boundaries of SASANOHA austenites and then they decompose to graphite and austenite on cooling. At the eutectoid temperature, the austenite transforms firstly to very fine pearlite, and then the pearlite or residual cementite neucleates normal pearlites in austenite matrix.
  3) It is hard to get a matrix coexisted with ferrite and pearlite in pure iron-carbonand in iron-carbon-silicon alloy, unless the small amount of manganese is contained. The promotion of ferrite might be attributed to its awn effect of manganese besides desulphurization effect of it. If sulphur is containd in iron, it requires more manganese to get ferrite because of its consumption of farming manganese sulphide.
  4) When iron-carbon-silicon-manganese alloy or commerical pig iron cools, it is not seldom that both ferrite and pearlite are seen. In this case, many thin flake graphites precipitate on cooling succeeding to the precipitation of original flake graphites along the Agr-line of the diagram, and ferrites crystallize out attaching to them at the eutectoid temperature followd by the pearlite formation. Pearlite appears on the boundary of ferrite and austenite or that of SASANOHA austenites by the process previously mentioned.
  5) When steadite existes, pearlite is also neucleated by it.
  6) The cooling curves of iron which contains both ferrite and pearlite indicate breaking and arresting points, the former corresponds to ferrite formation and the latter pearlite formation. It is suggested that the amount of ferrite could be related to the temperature interval between breaking and arresting points.
  7) Iron containing a small amount of tin promotes pearlite formation remarkably and makes less ferrite matrix. The iron contained more than 1.5% of tin rystallizes out some angular particles of white phase at the end of the eutectic reaction, which have strong power of pearlite neucleation at the eutectoid temperature.

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  To clarify the durability of inoculation in cast iron, the author carried out the experiment by the following method and founded on the results taken from the experiment, he made some considerations on the inoculation mechanism.
  The molten iron having low eutectic degree is inoculated by ferro-silicon and calcium-silicide and after then, this is kept at a certain temperature for various of intervals. From the change of casting structure and the graphitization, procedure, the effect of inoculation in time elapse is studied.
  The gists of the results are as follows :
  1) The variation of the durability of inoculation effect in casting structure and tbat of graphitization phenomena in white pig iron in time elapse is shown almost similar tendency.
  2) As the amount of inoculant increases, the durability of inoculation effect increases, but as higher the holding time of the melt, durability decreases.
  3) Calcium silicide has shown better effect than ferro-silicon in the points of inoculation effect and of durability.
  4) Partial concentration of graphitizing element contained in inoculant in the process of melting gives much important effect on the mechanism of inoculation than the effect of slight deoxdization of inoculant.

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  In spheroidizing the graphite in cast iron by means of calcium-silicide addition, it's recovery and it's spheroidizing effects are usually poor when it is added alone.
  The effects of calcium silicide, however, are remarkably improved when it is added jointly with fluxes.
  It was revealed that magnesium-fluoride was the most effective flux, for instance, by adding 2.5% calcium-silicide together with 1% magnesium fluoride on the melt in ladle, graphite in the castings was spheroidized.
  The above described method of producing the cast iron with spheroidal graphite is less dangerous, less complicated and more reliable compared with the ordinary method of magnesium addition.

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  The collapsibility is determined by measuring the time to be required to cause collapse of a test piece under constantly applied compressive load at an elevated temperature.
  The aim of this study is to obtain fundamental data on the collapsibility of shell molds, and some considerations of measuring conditions, experiments on various factors, relationship between several mechanical properties and collapsibility, etc. are reported.
  Main conclusions obtained were as follows :
  1) The collapsibility may be measured under any proper condition of compressive load and elevated tempreature, but for Fe-alloys, a measuring temperature of 800°C or more is recommendable.
  2) Collapse is caused by thermal decomposition of the resin contained in shell molds, and at a constant temperature, the rate of the thermal decomposition is considered mainly due to the air permeability of the mold, which is influenced by sand percentage, void or distance between sand particles. All those are governed by the flowability of sand-resin mixture, too. Moreover the flowability is a function of grain shape and size of the sand and resin percentage. Therefore fundamental variables of the collapsibility seem to be the grain shape, size and the resin percentage.
  3) The collapsibility is not influenced by curing temperature and time which are generally used.
  4) The collapsibility is proportional to the resin percentage in the range of its practical use.
  5) The following equations are the the relationship between the collapsibility and several mechanical properties ;
          C=a_t log σ_t+b_t
          C=a_c log σ_c+b_c
      log C=a_f log σ_f+b_f
          C=a_s σ_s+b_s
where C is the time requied to collapse, σ_t tensile strength, σ_c compressive strength, σ_f bond strength, σ_s surface strength (depth of scratch), and a and b are constants.

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  The author carried out the study on the manifold type gate and has established the method of gating design from the theoretical formula derived by the author. He thinks that the method of calculation established by Berger & Locke is unsatisfactory and that of Ohira is unfavorable because of entirely experimental. And he derived entirely theoretical formula at his first step of work as follows :
            [Written in non-displayable characters.]
            [Written in non-displayable characters.]
            α_x=(F/f_x)² (1+λ_x l_x/α_x +ζ_x
            β_x=λ_x L₂/D + ξ_x
  where     F_x : sectional area of channel
              L_x : distance between two ingates
              D : diameter of channel
              f_x : sectional area of No. x ingate
              α_x : diameter of No. x ingate
              l_x : length of No. x ingate
              ζ_x : coefficient of bend resistance
              ξ_x : coefficient of sudden change loss in viscosity
        λ_x, λ'_x : coefficient of pipe friction of ingate and channel
 This formula gives the distribution value of metal if the values of resistance at every part of ingate is given. The effects of pouring conditions such as pouring temperature and rate can not be supposed from this formula, but the effect due to the shape of ingate can be understood obviously.
  The author has ascertained the effects of these conditions by the experiment. Metals used in this experiment are cast iron and lead, and four and six ingates are used respectively.
  It has ascertained that the forementioned formula is applicable within the range of the pouring temperature of the metal is not so low as to cause solidification the metal in the channels and ingates.
  Satisfactory figure can be obtained when the normal values of coefficients of bend or pipe friction in case of water, are introduced in the formula. However, it is impossible to take a reasonable value of coefficient of pipe friction in the case of metal solidifies in gate.
  Some examples for gating design in which the metal distribution at each gate becomes equal, are also given in this article.
  The size of ingate can be determined from the following formula, because there is definite relation between the number of ingates and the size of each ingate.
            (F_i−1/F_o)²α_i+(n−i+1)²=(F_i−1/F_o)²α₃+(F_i−1/F_i)²(1+β_i)(n−i)²
  where     F_i : sectional area between ingate “i” and (i+1)
              F_o : sectional area to ingate 1
              n : number of ingate

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