Journal of the Society of Materials Science, Japan

Critical Behaviors of Elastic-Plastic Structures

Tsuneyoshi NAKAMURA, Koji UETANI

1981 Volume 30 Issue 333 Pages 535-548
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.535

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Fatigue Strength of Press-Fitted Specimen

Influence of Varying Stress Amplitude with Two-Level Multiple-Step on Fatigue Life

Hiroshi NAKAMURA, Toshiyasu TSUNENARI, Takeshi HORIKAWA, Tomonobu OKAD ...

1981 Volume 30 Issue 333 Pages 549-555
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.549

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Press-fitting is widely used for railroad axles, crank shafts, etc.. A lot of investigations on fatigue strength of press-fitted specimens have been so far carried out. However, many of them were done under constant stress amplitude conditions and only few investigations under varying stress amplitude have been reported.
In the present study, rotating bending stress tests were carried out on press-fitted specimens under varying stress amplitude conditions which were composed of two-level multiple-step stresses, ; one stress amplitude was higher than fatigue limit (the over stress) and the other was lower than that (the under stress). The specimens were made of medium carbon steel (S35C), and the diameters of the specimens were 10mm and 50mm. The 10mm diameter specimens were in the as received condition and the 50mm diameter specimens were in four heat treatment conditions; as received, tufftrided, induction hardened, and tufftrided after induction hardened.
The results obtained are summarized as follows;
(1) Under the varying stress amplitude, the under stress gave a fatigue damage to the specimens and the cumulative damage calculated by Miner's rule was very much less than unity.
(2) Haibach's modification of S-N diagram was more suitable than the modified Miner's rule for calculating the damage of the under stress in the range of these experiments.

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Effect of Trace Elements on Recrystallization Temperature of Silver

Shigenori HORI, Hideo TAI, Seiichi KAWAGUCHI

1981 Volume 30 Issue 333 Pages 556-561
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.556

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The present investigation is concerned with the influence of solute element atoms on the recrystallization temperature of cold-rolled silver. The materials containing 0.03∼1.8 at% each of Be, Mg, Pd, Cu, Au, Cd, Al, In, Ge, Sn, Pb, Sb, or Bi were cold-rolled to 90% reduction of area and annealed for 10 minutes at various temperatures. The recrystallization temperature was obtained by hardness measurement.
At any rate, all solute elements raised the recrystallization temperature of silver with increasing their content. The most pronounced influence on the recrystallization temperature was found to be brought in by the addition of the elements which have a much larger absolute linear size factor, excess valence and smaller maximum solid solubility. The magnitude of the increase in recrystallization temperature seems to be related to the binding energy of solute atoms with vacancy, dislocation and grain boundary.

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Deformation of Steel Pipe during Hot Dip Zinc Galvanizing

Masatoshi KIKUCHI, Tohru IEZAWA

1981 Volume 30 Issue 333 Pages 562-568
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.562

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It is well known that residual deformation is retained in hot dip zinc galvanized steel structural members. This deformation is mainly caused by thermal deformation which occurs when the members are dipped into molten zinc. Therefore, in order to consider the countermeasure for the occurence of such residual deformation, it is very important to investigate the thermal deformation and thermal stress caused by dipping. However there are very few reports on these kinds of transient deformation and stress.
In this study, the cross-sectional deformation and the thermal strain of a steel pipe (φ660.4× 18, L=3500mm) were measured on the specimens dipped into 460°C molten zinc from 20°C by using displacement transducers and capsule type high-temperature strain gages, respectively. They were also analyzed by using the finite element method (FEM) and the results were compared with those of the experiments.
The main results obtained are as follows:
(1) The measured variations of deformation and thermal stress for a steel pipe dipped into molten zinc coincided well the results analyzed by using FEM in sequence.
(2) The total deformation and the thermal stress of the steel pipe varied with the dipping speed: the thermal deformation as well as the thermal stress decreased with increasing dipping speed.

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Yield Behavior in Bending of Rigid Plastics

Yasuo SATO, Hiizu HYAKUTAKE

1981 Volume 30 Issue 333 Pages 569-573
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.569

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The yield behavior of polycarbonate and polyvinyl chloride subjected to bending was investigated by uniform bending tests using beams with several kinds of cross section. Particular attention was given to the effect of the macroscopic stress distribution in the specimen on the yield behavior.
It has been shown that by observation in tension and compression tests, the yield behavior of rigid plastics can be deviled into two distinct processes; the initiation process of yield accompanying load drop and the progressive process of yield under constant load. This suggests that there are two kinds of yield stresses. Thus, in order to get a general interpretation of yield of plastics, the two kinds of yield stresses should be taken into consideration.
The yield behavior in bending has been analysed in terms of two kinds of yield stresses for rigid plastics, and the relation between the bending moment and strain on the surface of beam has been determined quantitatively. The calculated results were confirmed by the experiments.

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A Law of Fatigue Crack Propagation on the Basis of A Stochastic Model for Damage Accumulation

Chiaki IHARA, Akito IGARASHI

1981 Volume 30 Issue 333 Pages 574-578
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.574

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The fatigue crack growth rate was investigated on the basis of a dislocation multiplication model for damage accumulation on which the fatigue life up to crack initiation was evaluated. A two-dimensional version of a stochastic model proposed by Tsurui and one of the authors (A. I.) was used in order to obtain the expression of the rate of fatigue crack growth, and a distribution function of the strength of material elements was derived by the use of the dislocation multiplication model. The results show that the fatigue crack growth rate is proportional to some power of the range of the stress intensity factor. The theoretical results were compared with the experimental data.

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Statistical Method to Evaluate the Scattering Fatigue Data Considering Both of Life and Strength Distributions

Jun-ichi ARAI, Hideo IWAKI, Yukio INO

1981 Volume 30 Issue 333 Pages 579-583
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.579

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In this paper, a statistical method to evaluate the fatigue data has been proposed by considering a two dimensional distribution on the life-strength plane (S-N plane). This evaluation method is based on the assumption that the data of S-N curve can be treated as the members of the set, which has a two dimensional normal distribution around the peak point in the coordinates of life and strength axis, and the variance of this two dimensional normal distribution can be given from the life and strength distributions of the original S-N data. A contour line of this two dimensional distribution is of elliptical shape, and represents the probability range.
Furthermore, the contour line having the same probability of S-N curve can be obtained from the envelope curve of the contour lines having the same probability of subgroups which have also the two dimensional normal distribution. The region enclosed with this curve expresses the probability of fracture occurrence. The fatigue limit is defined as the tangent line of this contour line, which is paralled to the life axis.
As an example, the S-N data obtained by Nishijima et al. were analyzed. It was confirmed that the contour lines of the same probability obtained by the above mentioned method were in good agreement to that of the sample S-N data.

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Effect of Environments on Fatigue Crack Propagation Behavior of SNCM8 in Rotating Bending

Masaki NAKAJIMA, YOZO KATO, Motohisa HIROSE, Norihiko HASEGAWA

1981 Volume 30 Issue 333 Pages 584-589
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.584

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The influence of corrosive environments on the fatigue crack growth rate of SNCM8 was investigated. The material used was tempered at 200°C to give a yield strength level of 150kgf/mm²·Tests were made at stress intensity levels below K_ISCC in room air, distilled water and 3.5% NaCl solution.
Since the formula of stress intensity was unknown, the data were analyzed by using the stress intensity of an infinite cracked plate with uniform stress at infinity. Moreover, in order to consider the effect of hydrogen on this material, hydrogen-precharged specimens were tested in the same environments.
The results obtained are as follows:
(1) The fatigue crack growth rate in corrosive environments was 3-5 times faster than that in room air. However, it is considered that the growth rate in room air is accelerated by water vapor in air. The growth rate at lower stress intensity in 3.5% NaCl was a little faster than that in distilled water.
(2) Independent of the stress level during precracking and corrosive fatigue stressing, the growth rate was represented well by the formula above-mentioned.
(3) Precharged hydrogen accelerated the fatigue crack growth. This effect was remarkable for precracked specimens and in room air.
(4) Fracture surfaces have both striation-like pattern and intergranular facet pattern in the above environments. In corrosive environments intergranular facet pattern increased. These results suggest the occurrence of hydrogen embrittlement.

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Fatigue Crack Growth Behavior for Through and Part-Through Cracks in C-Shaped Specimen

Kazumi HIRANO, Akira ISHII, Hideo KOBAYASHI, Hajime NAKAZAWA

1981 Volume 30 Issue 333 Pages 590-594
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.590

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A C-shaped specimen is suitable for testing thick-walled cylinders. Fatigue crack growth tests were conducted by using the through cracked specimens with different ratios of outside to inside radius. It was shown that the fatigue crack propagation rate, da/dN, was related uniquely to the stress intensity factor range, ΔK, by following expression,
da/dN=C(ΔK)^m
This relationship is consisted with that obtained by using the compact specimens fabricated from the same orientation.
From the fatigue crack growth tests using the surface cracked specimen, it was shown that the crack depth could be measured accurately by the End-on ultrasonic method, and the aspect ratio variation chracteristics with increasing crack depth was clarified. Moreover, it was found that the fatigue crack propagation rates, da/dN and db/dN, in the specimen width and through thickness directions were related to the presumed stress intensity factor ranges, ΔK_a and ΔK_b, respectively.

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J_Ic Evaluation Using C-Shaped Specimen by Ultrasonic Method

Kazumi HIRANO, Hideo KOBAYASHI, Hajime NAKAZAWA

1981 Volume 30 Issue 333 Pages 595-599
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.595

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In this study, the proposed elastic-plastic fracture toughness test procedure based on Top-on and End-on ultrasonic methods was applied to J_Ic tests for the C-shaped specimen, and it was pointed out that the load and load point displacement at the onset of stable crack growth during fracture toughness loading can be detected from a single specimen by the End-on ultrasonic method. J_Ic, measurements obtained for the C-shaped specimen were in excellent agreement with that obtained for the compact specimen. The J_Ic value evaluated according to the proposed J_Ic test procedure was also in agreement with that determined according to the SZ method, but was not consistent with that determined according to the R-curve method.

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Role of Viscosity Playing in the Formation of B₂O₃-Na₂O Binary Glasses by Quenching Method

Rikuo OTA, Naohiro SOGA

1981 Volume 30 Issue 333 Pages 600-606
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.600

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The glass-forming region in the B₂O₃-Na₂O system was tried to interpret on the basis of an assumption concerning the glass-forming ability of a substance that higher viscosity melts will make a glass when quenched at an appropriately rapid rate, while lower viscosity melts will not. Ten grams of B₂O₃-Na₂O melts were water-quenched at a rate of 7°C/sec, and two glass-forming regions were determined. The upper glass region was 100∼61 mole per cent B₂O₃ and the lower glass region was 32∼28 mole per cent B₂O₃. Viscosity was measured by a counter-balanced viscometer at elevated temperatures above the liquidus temperature, and the liquidus viscosity log η_l was obtained for the compositions of 100∼25 mole per cent B₂O₃. The liquidus viscosity curve plotted as a function of B₂O₃ content for the B₂O₃-Na₂O system exhibited two maxima and two minima in viscosity. It was found that the glass regions, 100∼61 and 32∼28 mole per cent B₂O₃, corresponded quite closely with the regions where the liquidus viscosity was higher than log η_l (poise)=0∼0.1. The single-bond strength B_M-O and the Rawson's parameter B_M-O/T_l for glass formation were calculated and were compared with the glass-forming regions of this system. These parameters were found unsatisfactory to explain the glass-forming ability of the lower glass region. But the liquidus viscosity described rather quantitatively the existence of the separate glass regions in the B₂O₃-Na₂O system.

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Thermal Fatigue Test of Ceramics by Ring Test

Manabu TAKATSU

1981 Volume 30 Issue 333 Pages 607-610
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.607

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In the present paper, an experimental method of testing multicycle fatigue of ceramics was investigated. When the inner surface of a ring is heated by a constant heat flux, the resulting thermal stress can be easily estimated. By using this merit, the relation between the thermal stress and the fracture time of some ceramics was measured. A nearly linear relation was obtained when the data were plotted on a log-log graph paper. The technical meaning of the slope of the line was also considered.

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Deformation Behaviors of Metals and Alloys at Elevated Temperature

6. Controlled Rolling of Steel (I) -Reduction in Recrystallization and Non-Recrystallization Regions-

T. Tanaka

1981 Volume 30 Issue 333 Pages 611-617
Published: June 15, 1981
Released on J-STAGE: June 03, 2009

DOIhttps://doi.org/10.2472/jsms.30.611

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