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Volume 28, Issue 11
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[in Japanese]1959 Volume 28 Issue 11 Pages 771-778
Published: November 25, 1959
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSDownload PDF (661K) -
1959 Volume 28 Issue 11 Pages 779-785
Published: November 25, 1959
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSDownload PDF (4896K) -
Experimental Apparatus and Preliminary InvestigationH. Suzuki, T. Bada, H. Nakamura1959 Volume 28 Issue 11 Pages 786-792
Published: November 25, 1959
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSTwo grades of stainless steels, wrought round bars of type 347 alloy and Croloy 16-8-2 Cr-Ni-Mo alloy, were subjected the RPI hot ductility test by the authors' experimental apparatus and the following results were reached:
(1) The investigation showed that the hot ductility curves of both grades obtained by the experimental apparatus agreed satisfactory with those reported by Nippes RPI.
(2) Both grades studeid showed that the prior thermal history markedly affected the hot ductility. In general, short exposures to a temperature 1340°C caused a significant reduction in the hot ductility measured at temperatures during the cooling portion of the thermal cycle. The hot ductility of type 347 during the cooling portion was for inferior to that of 16-8-2 Cr-Ni-Mo alloy at testing temperatures between 1200°C and 1300°C.
(3) Microscopic observation indicated that this phenomenon was closely related with embrittlement due to grain boundary liquation, and the degree of embrittlement of type 347 was for greater than of 16-8-2 Cr-Ni-Mo alloy.
(4) Microscopic observation also showed that the fractures of both grades tested were of intergranular type when heated above 900°C.
(5) The values of hot ductility of type 347 during the coling portion of the thermal cycle showed considerable scatter, while that of 16-8-2 Cr-Ni-Mo only appreciable.View full abstractDownload PDF (10958K) -
K. Kato1959 Volume 28 Issue 11 Pages 793-798
Published: November 25, 1959
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSElectron microscope and electron diffraction method were applied to study non-metallic inclusion in mild steel weld metal. The shape of smaller particle of inclusion were sphere in almost cases. Diffraction patterns of these particles could not find in many cases, but a few results were obtained as follows. Several kinds of SiO2 crystals were found in low hydrogen type weld metal and MnO were found in ilmenite type. Auther considered the relation between these crystal formes and type of electrode coating and the mechamism of formation of inclusion particles in weld metal.View full abstractDownload PDF (11826K) -
Effects of Carbon, Manganese and Silicon Contents on Critical Cooling Times of SteelsH. Sekiguchi, M. Inagaki1959 Volume 28 Issue 11 Pages 799-806
Published: November 25, 1959
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSBy this time, the authors constructed and reported many continuous cooling transformation diagrams in case of maximum heating temperature 1350°C for numerous kinds of mild steel and Mn-Si type high tensile steel showing various tensile strengths in the range of 35-57kg/mm2. In this report, chemical analyses of numerous kinds of mild and Mn-Si type high tensile steels, continuous cooling transformation diagrams for these steels, critical cooling times Cz', Cf', Cp', Ce' and 50% martensite cooling time obtained from the above mentioned diagrams are summarized. In particular, relations between the Cz'-, Cf'- cooling time or the 50% martensite cooling time and C-, Si- or Mn-content of steels were discussed, and the following experimental formulas were determined:
{log(50%MCT)=8.79Ceq-1.52
log Cf'=8.59Ceq-1.69
log Cz'=7.84Ceq-1.81
where Ceq=(C+1/12Mn+1/24 Si)%.
These formulas were obtained for killed, semi-killed and rimmed steels containing 0.10-0.18% C, 0.01-0.53% Si, 0.41-1.40% Mn and P, S, Cu, Ni, Cr, etc. as impurities.
When those results obtained in this report and the method for predicting cooling times from welding conditions, mentioned in other reports by one of authors, are combined, the optimum welding conditions of optional steels used can be determined previously. On this occasion the Cf' critical cooling time of a steel is an important criterion for this determination.View full abstractDownload PDF (633K) -
On 60 kg/mm2 High Tensile SteelH. Sekiguchi, M. Inagaki1959 Volume 28 Issue 11 Pages 807-814
Published: November 25, 1959
Released on J-STAGE: December 10, 2009
JOURNAL FREE ACCESSIn the previous reports, the continuous cooling transformation diagrams were constructed for many mild steels and Mn-Si type high tensile steels. In this report, the continuous cooling transformation diagrams in case of maximum heating temperature 1350°C have been constructed for steels containing a small quantity of Ni, Cr, Mo, V and Ti in addition to Mn and Si and having ultimate tensile strength of about 60 kg/mm2.
The field of the intermediate structure (Zw) in the continuous cooling transformation diagrams of this type of steel is extending through an extremely long range of cooling time, differing from those of mild steels and Mn-Si type high tensile steels. This fact is considered to be relating to the high tensile strength and excellent weldability of this kind of steel.
The effect of carbon content on critical cooling times for these types of high tensile steel is remarkable, as well as the case of mild steels and Mn-Si type high tensile steels. The critical cooling times Cz', Cf', Cp' and 50% martensite cooling time of steel YF containing 0.18% C differ remarkably from those of steel YG containing 0.11% C. If the carbon content of this type of steel is as low as that of steel YG, critical cooling times Cz', Cf', Cp' and 50% martensite cooling time of that steel have a tendency to approach to those of mild steel.View full abstractDownload PDF (6052K) -
Weldability Tests of Ni-Cr-Mo Steel (2)Y. Ito, M. Kamo, Y. Araki, B. Miyanaga, K. Nikuma1959 Volume 28 Issue 11 Pages 815-822
Published: November 25, 1959
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSPast experimental report shows that Slit Test, C.T.S. Test, Maximum Hardness Test of Weld Heat-Affected Zone, Single Bead Bending Test, V-Notched Charpy Impact Test are available to infer the weld crack sensitivity of low alloy high strength steel, except C.T.S. Test.
In order to determine the weldability on this report, above four testing methods are applied for 25 mm thick Ni-Cr-Mo low alloy high strength steel plates which have different hardness with dissimilar heat treat conditions.
Following results is given about low alloy high strength steel by this comparative weldability test.
(1) Cast steel plate shows far inferrior weld crack sensitivity than rolled steel plate.
(2) Original hardness of base steel shows almost no effect for the crack sensitivity of weld heataffected zone.
(3) Slit Test shows excellent effect as the way to determine the weld crack sensitivity.
(4) Maximum Hardness Test of Weld Heat-Affected Zone is effective to infer the weld crack sensitivity to certain extent.View full abstractDownload PDF (4795K) -
Acetylene Generating in Sodium Chloride Water SolutionI. Unda, Y. Imai, H. Shinotani1959 Volume 28 Issue 11 Pages 823-826
Published: November 25, 1959
Released on J-STAGE: June 12, 2009
JOURNAL FREE ACCESSIt is common practice to use sodium chloride saturated water solution instead of water for determine the acetylene generating rate.
But, practically nothing is known about the influence of sodium chloride on the chemical reaction between calcium carbide and water.
With the object to clear this influence, we executed the repeated acetylene generating tests by carbide dipping in water and sodium chloride saturated water solution and compared its influence.
By precise observations, we recognized that the temperature raising in water is visibly higher than in sodium chloride saturated solution.
Hence, this proves surely that sodium chloride saturated water solution will disturb gas generation.
Accordingly to Author's further research of this phenomenon, the reaction rate from the surface of a carbide lump to centere is lower about 10% than in water.
Retardation of the acetylene generating rate in sodium chloride water solution will be caused by following factors that is ;
(1) Suspended white slime remains fairly longer time than in water.
(2) Bubbles and foams on the gas generated solution surface are relatively stable and these layers are thick in sodium chloride saturated water solution.
In the case of (1) item, for example, 88 weight % of floating slime precipitated in water, but 70 weight % in sodium chloride saturated water solution, its generation will occur in more slush solution state (Fig. 1).
Generated bubbles and foams are unstable in the case of water, therefore, disappears immediately.
This phenomenon will attribute to promote acetylene generation (Fig. 5 (a), (b)).View full abstractDownload PDF (2933K)
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