Transactions of Japan Society of Spring Engineers

Study on Fracture Toughness of Spring Steel

Toshio OZONE, Nobuhisa YOKOTE, Mamoru KURIMOTO

1983 Volume 1983 Issue 28 Pages 1-5
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.1

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Fracture toughness has become a useful means to evaluate the toughness of spring steels in a region of high hardness. For example, the coil springs for automotive suspension have a tendency to become harder so as to prevent them from sagging, where in such a hard region the impact test is difficult to apply for its poor accuracy. Thus, the evalyation of the toughness should be made by fracture toughness test for hard tempered spring steels.
The present study concerned with the fracture toughness of the spring steels specified JIS (Japanese Industrial Standards) and the experimental steels with addition of Cr and other well known elements to SUP 6 and SUP 7. Of specified spring steels, SUP 10, Cr-V steel showed the highest fracture toughness, leaving both of SUP 9A and SUP 11A lowest. The addition of Cr into a high silicon steel such as SUP 7 was found to impair the fracture toughness in a drastic way, but the content of Si between 1.6 to 2.5% in Si-Mn steel had no effect on the fracture toughness.

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Deformability and Hot Deformation Resistance of Spring Steel

Michihiko AYADA, Toyoyuki HIGASHINO, Kanji INOUE

1983 Volume 1983 Issue 28 Pages 6-13
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.6

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In the processes of hot working of metal, it is essencial for manufacturing to know the deformability and deformation resistance of the material. They would have great correlation with the structure change of the material, which may occur with the recovery or recrystalization.
In the IRON and STEEL INSTITUTE of JAPAN, the systematical studies about this area have been carried out from 1977. However, few studies for spring steel have been made so far. The aim of this paper is, therefore, to study the deformability and deformation resistance of spring steel from room temperature to high temperature.
It was found that the deformability and deformation resistance showed the maximum value and minimum value at the blue shortness area (200°C-400°C) and just below the A₃ transformation point, respectively.
As for the equation of the deformation resistance of spring steel at elevated temperature, it was realized that the SHIDA's equation would be suitable.

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Torsional Fatigue Strength of Piano Wires under the 2-Step Multiple Repeated Varying Strain Amplitudes

3rd Report, Effect of Corrosion Terms

Akio GENTSU

1983 Volume 1983 Issue 28 Pages 14-22
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.14

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In order to investigate the torsional fatigue strength of the corroded specimen, the author was carried out the torsional fatigue tests under the condition the multiple repeated varying strain in two strain levels. The test specimens consist of 0.84% C Piano wires corroded 3 months, 6 months and 12 months in 3% NaCl solution.
The principal results obtained are summarized as follows:
(1) The fatigue strength of Piano wires corroded in 3% NaCl solution is much lower than that in air. The rate of decrease in fatigue strength is smallest for 3 months corroded specimen, and was largest for 12 months corroded specimen among three corrosion terms.
(2) From the torsional fatigue test results under 1-step varying strain amplitude in air obtained by using the linear damage criterion is possible an estimate of the fatigue life of the corroded specimen.
(3) The test result shows the linear relationship between the total hysteresis energy and the number of cycles to fracture or the total varying strain amplitude, when they are plotted on a log-log scale.

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Study of the High Strength Stainless Steel wires for Springs

Yoshiaki KOIZUMI, Hiroaki HAYASHI, Hideaki SHIMODA

1983 Volume 1983 Issue 28 Pages 23-38
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.23

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SUS 304-WPB stainless steel wire has been used generally for springs in Japan. In the case of special purposes for spring usage such as high fatigue properties or heat resistance are required, SUS 631 JI-WPC (17-7 PH) has been applied. Recentry in U.S.A (1980), new type of high strength wire which was stregthened by drawing at subzero temperature was added to the ASTM A 313 code as Type 302 Class 2.
We examined mechanical properties, fatigue properties, corrosion resistance and others in comparison test with the above mentioned stainless steel wires and SUS 304 N2 steel wire. In the evaluation of heat resistance, the quality of subzero-drawing wire was intermediate between SUS 304-WPB and SUS 631 JI-WPC. In fatigue properties, subzerodrawing wire was suprior to SUS 304-WPB and typical SUS 631 JI-WPC.

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Contact Performance of the Solder-coated Phosphor Bronze Plates

Toshihiro KUNII, Akira IKEDA, Takashi TAKEYARI

1983 Volume 1983 Issue 28 Pages 39-45
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.39

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The development of the low-priced and marti-fanctional spring, which has the abilities of contact and solderability, is desired. Then, we carried out a trial production of solder-coated phospor bronzeplates. In this paper, the contactability, solderability and creep-performance of these materials are discussed. And the results are as follows.
(1) The solder-coated phosphor bronze plates were extremely superior to the balk phosphor bronze plate, in the contactability and solderability. And the solder-coated phosphor bronze plates hardly changed in these ability, after damp heat test (40°C, 90% R. H.).
(2) The contactability and solderability were tested on a few chemical components of coated solder. Then, 65/35 tin/lead solder was superior to 90/10 tin/lead solder in the stability of those abilities.
(3) The solder-coated phosphor bronze plates had larger index of creepdeformation as compared with the balk phosphor bronze plate.
(4) The solder-coated phosphor bronze plates will be useful to the materials for use of contactable springs.

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Design of the Hollow Stabilizer

Kanji INOUE

1983 Volume 1983 Issue 28 Pages 46-54
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.46

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For the purpose of weight-saving of automobile, stabilizer (anti-roll bar) is now being designed by tube. This paper is mainly concerned with the basic consideration of designing hollow stabilizer. The mechanics of the stress distribution which occurs to hollow stabilizer, was obtained experimentally.
It was found that the stress condition of hollow stabilizer was entirely different from that of solid stabilizer. The application of pipe factor makes it possible to predict the design stress of hollow stabilizer. The experimental results have good agreement with the calculated results obtained by Finite Element Method. Following the design method obtained here, experiments were extended to fatigue tests, and much useful information for manufacturing hollow stabilizers, especially for appropriate tubing materials, was obtained.

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Durability of Tubular Stabilizer Spring

Junichi HIGUCHI, Shuji KAMIYA

1983 Volume 1983 Issue 28 Pages 55-59
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.55

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To reduce vehicle weight, stabilizer using hollow material is being put into practice. Hollow stabillizer has a higher actual stress than the calculated value as the bent part becomes flat due to formation. This paper describes a simple method to obtain the actual stress.
As the factors to cause flatness, the bending radius, plate thickness and outer of a tube are taken up to define the bending degree which enables to expect the actual stress and life-time as well as to select an optimum material. In addition, the influence of weld bead, shot peening and corrosion to the durability has also been cleared.

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Fractgraphy on Fatigue Fractore of Wire Springs

Yoshiaki KOIZUMI, Hideaki SHIMODA, Tetsuo SAITO

1983 Volume 1983 Issue 28 Pages 60-71
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.60

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This paper describes the features of fatigue fracture of coil spring fractured in a fatigue test or actual use through the observation with an electron microscope.
The starting point of fatigue fracture of silicon chrome steel wire and piano wire for the valve spring fractured in a spring fatigue test is classified into the following three forms.
a. Fracture form with fish eye where the starting point of fatigue fracture is on non-metallic inclusion.
b. Fracture form where an initial crack of shear type exists on the starting point of fatigue fracture.
c. Fracture form where an initial crack of tension type is caused on the starting point of fatigue fracture.
The paper also describes the features of fracture caused by surface flaw, fretting damage insufficient shot peening, decarburization and corrosion in actual use.

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Positioning of Coiling Tool in 1-Finger System with Coiling Mandrel

Kazunori TSUSHIMA, Takahiko KUNO, Kunishige SAITO

1983 Volume 1983 Issue 28 Pages 72-80
Published: March 31, 1983
Released on J-STAGE: February 26, 2010

DOIhttps://doi.org/10.5346/trbane.1983.72

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The summary of the results is shown below.
(1) Experimental values agree well with the theoretical results on the assumption that the wire forming curve to helical springs consists of straight line and circular arc.
(2) It is desirable to move coiling point in the direction of a fixed angle, because it is obtained in 1-finger system that the angle between wire guide groove line and the line from wire guide outlet to coiling point is constant independent of spring index.
(3) When coiling point is moved parallel along the axis of mandrel, the required winding pitch is obtained. But spring index (D/d) is invariable within the limits of this experiment (D/d=7-17) even if the winding pitch is varied in the above-mentioned method.

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