Influence of Heat Treatment on Fatigue Strength of Drawn Steel Tubes for Small-Sized Single Pass Boiler

2011 ◽  
Vol 275 ◽  
pp. 109-112 ◽  
Author(s):  
Daisuke Yonekura ◽  
Yuta Fujie ◽  
Hayato Nishii ◽  
Hiroshi Yamakawa ◽  
Riichi Murakami
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Grain Size ◽  
Fatigue Strength ◽  
Steel Tube ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Post Heat Treatment ◽  
Single Pass ◽  
Heat Treated

Tension-tension fatigue tests were performed to examine the influence of post drawing heat treatment on the fatigue properties of drawn specific steel tube (STB340) for small-sized single pass boiler. The untreated, as-drawn and post drawing heat treated series were prepared for fatigue tests. The hardness, grain size and residual stress were measured for each series. As a result, the change of grain size and residual stress was small after post heat treatment. The drawn series was softened by post heat treatment but the hardness was still higher than untreated samples. The fatigue strength of the as-drawn and the post drawing heat treated series was higher than that of untreated series. In addition, the difference of endurance limit was small between as-drawn and post drawing heat treated series.

scholarly journals INFLUENCE OF CARBON CONTENT ON FATIGUE STRENGTH OF DRAWN STEEL TUBES FOR SMALL ONCE-THROUGH BOILER

2012 ◽  
Vol 06 ◽  
pp. 361-366
Author(s):  
DAISUKE YONEKURA ◽  
YUTA FUJIE ◽  
RI-ICHI MURAKAMI ◽  
YUKIHIRO TOKUNAGA
Keyword(s):  
Heat Treatment ◽  
Fatigue Strength ◽  
Carbon Content ◽  
Steel Tube ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Post Heat Treatment ◽  
Steel Tubes ◽  
Heat Treated ◽  
The Difference

Tension-tension fatigue tests were performed to examine the influence of carbon content on the fatigue properties of drawn specific steel tube (STB340) with/without post heat treatment for small once-through boiler. Two different carbon content steel tubes, C =0.06 and 0.12% were prepared. The as-received, as-drawn and post drawing heat treated series for each carbon content tube were prepared for fatigue test. The hardness, grain size and residual stress were measured for each series. As a result, the fatigue strength of as-received and as-drawn series showed a small difference between C =0.06 and 0.12% specimens. However, the post drawing heat treatment series showed obvious difference in the fatigue strength. The fatigue strength of higher carbon content tubes significantly decreased by the post drawing heat treatment, whereas the decrease of fatigue strength was little for lower carbon content heat treated tubes. The difference of fatigue strength was mainly caused by the degree of relaxation of work hardening by post heat treatment.

Fatigue Behavior of Age-Hardening Cu-6Ni-1.5Si Alloys with Different Grain Sizes

2021 ◽  
Vol 1016 ◽  
pp. 125-131
Author(s):  
Masahiro Goto ◽  
T. Yamamoto ◽  
S.Z. Han ◽  
J. Kitamura ◽  
J.H. Ahn ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Fatigue Strength ◽  
Solution Heat Treatment ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
The Other ◽  
Age Hardening ◽  
Grain Sizes ◽  
Thermomechanical Processes

On the thermomechanical treatments of Cu-Ni-Si alloy, cold-rolling (CR) before solution heat treatment (SHT) is commonly conducted to eliminate defects in a casting slab. In addition, a rolling is applied to reduce/adjust the thickness of casting slab before SHT. In a heavily deformed microstructure by CR, on the other hand, grain growth during a heating in SHT is likely to occur as the result of recrystallization. In general, tensile strength and fatigue strength tend to decrease with an increase in the grain size. However, the effect of difference in grain sizes produced by with and without CR before SHT on the fatigue strength is unclear. In the present study, fatigue tests of Cu-6Ni-Si alloy smooth specimens with a grain fabricated through different thermomechanical processes were conducted. The fatigue behavior of Cu-Ni-Si alloy was discussed.

Fatigue Properties of Nitride Cr-Mo Steel with CrN Thin Film Deposited by Aip Method

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1554-1559 ◽  
Author(s):  
Daisuke Yonekura ◽  
Atsushi Tsukuda ◽  
Ri Ichi Murakami ◽  
Koji Hanaguri
Keyword(s):  
Thin Film ◽  
Residual Stress ◽  
Fatigue Strength ◽  
Film Thickness ◽  
Compressive Residual Stress ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Three Point Bending

In this study, we selected the nitride Cr-Mo Steel SCM435 as the substrate. Attention was focussed on the effect of film thickness. The Arc Ion Plating was performed using Cr cathode and N2 gas. The specimens were prepared for the film thickness 6, 12 and 18μm The three point bending fatigue tests were performed at room temperature in a laboratory environment. After the fatigue test, crack initiation sites were examined by using an optical microscope and a scanning electron microscope. The results obtained were as follows: (1) A high compressive residual stress generated in the film, and the compressive residual stress of 12μm film thickness was the greatest. (2) The fatigue strength of coated specimens for thin film was slightly lower than for substrate. (3) The film thickness hardly affected the fatigue strength of coated specimens.

scholarly journals Effect of Post-Heat Treatment Cooling Conditions on Microstructures and Fatigue Properties of Cobalt Chromium Molybdenum Alloy Fabricated through Selective Laser Melting

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1005
Author(s):  
Hla Htoot Wai Wai Cho ◽  
Atsushi Takaichi ◽  
Yuka Kajima ◽  
Hein Linn Htat ◽  
Nuttaphon Kittikundecha ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fatigue Life ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Post Heat Treatment ◽  
X Ray ◽  
Cooling Conditions ◽  
Cobalt Chromium Molybdenum

Although post-heat treatment can improve the fatigue life of selective laser melting (SLM)-fabricated cobalt chromium molybdenum (CoCrMo) alloys, the effect of cooling conditions on the fatigue properties of such alloys remains unclear. In this study, we fabricated SLM CoCrMo alloy specimens and, after heat-treating them, cooled them either via furnace-cooling (FC) or air-cooling (AC). Subsequently, we analyzed their microstructures using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy, electron backscattered diffraction, confocal laser scanning microscopy, and X-ray diffraction. Tensile and Vickers hardness (HV) tests and axial-fatigue tests were also conducted to assess their mechanical and fatigue properties, respectively. The microstructures of all samples showed homogeneous equiaxed grains, with the grains and precipitates of the AC samples (grain size: 84.9 μm) smaller than those of the FC samples (grain size: 109.7 μm). The AC samples exhibited better ductility than the FC samples. However, we observed no significant differences in the 0.2% yield strength and HV tests. The S–N curve derived from the fatigue tests showed that the AC samples had greater fatigue life than the FC samples. Therefore, a high cooling rate during post-heat treatment is effective in reducing grain and precipitate sizes, resulting in improved ductility and fatigue life.

A Study on the Development of Mach Peening for Prolonging Fatigue Life of Machine Structural Alloy Steel

2008 ◽  
Vol 580-582 ◽  
pp. 621-624
Author(s):  
Bok Kyu Lim
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Alloy Steel ◽  
Compressive Residual Stress ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Light Weight ◽  
Structural Alloy ◽  
Bending Fatigue

The light weight components, crucial in automobiles and machinery, is require hight strength. Mach peening process is one of many of techniques utilized for improving fatigue properties. From the results of rotary bending fatigue tests, the fatigue strength increases up to 129% in mach peening specimen compared with un-peening. A layer of highly compressed residual stress is obtained by mach peening. The compressive residual stress, induced by mach peening, seems to be an important factor for increasing the fatigue strength.

Effects of Modified Solution Heat Treatment on δ- Phase and Low Cycle Fatigue Properties of Inconel 718 Alloy

2006 ◽  
Vol 118 ◽  
pp. 71-76 ◽  
Author(s):  
Jae Keun Hong ◽  
Ji Hong Park ◽  
Nho Kwang Park ◽  
Seong Jun Kim ◽  
Chung Yun Kang
Keyword(s):  
Heat Treatment ◽  
Solution Heat Treatment ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Alloy 718 ◽  
Cycle Fatigue ◽  
Standard Heat ◽  
Heat Treated

Effects of solution treatment on the microstructure and mechanical properties in wrought Alloy 718 were investigated. For the improvement of tensile and fatigue properties of wrought Alloy 718, a modified solution heat treatment(MSHT), heating at 1000 for 3 minutes followed by furnace cooling at the rate of 3/minute and holding at 985 for 8 minutes, was proposed. This treatment was performed repeatedly 3 times and the samples were subject to the standard aging treatment. For the purpose of comparison, a standard heat treatment(SHT) was also performed. The microstructures of modified solution heat treated specimens showed that small spherical shaped δ- phases were precipitated without grain growth, and the amount of δ-phases was smaller than that of standard heat treated specimens. However, the δ-phases of the standard heat-treated specimen showed needle-like morphologies. Tensile and low cycle fatigue tests were performed on both modified heat-treated and standard heat-treated specimens at room temperature, 350 and 650. Low cycle fatigue tests on the modified heat treated specimens showed promising results without reduction of strength. However, the tensile properties of modified solution treated specimens was almost the same as those of standard heat treated materials both at room temperature and 650.

Effect of Shot Peening on the Long Life Fatigue Properties of Ti6Al4V with Different Heat Treatment

2015 ◽  
Vol 664 ◽  
pp. 81-86 ◽  
Author(s):  
X.J. Cao ◽  
Luo Peng Xu ◽  
Chong Wang ◽  
Jiang Jin ◽  
Qing Yuan Wang
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Shot Peening ◽  
Oxide Inclusion ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Almen Intensity ◽  
Ultrasonic Fatigue ◽  
Long Life

In order to investigate the effect of shot peening on the long life fatigue properties of Ti6Al4V (TC4), ultrasonic fatigue tests were performed with a frequency of 20 kHz. According to different heat treatment, two groups of specimens were surface modified by shot peening with an Almen intensity of 0.10 mmA~ 0.15 mmA and an overlapping rate of 100%. One group was stress-relief annealed at 650 °C, and the other was then treated with solution-aging. With the shot peening, both the depth of the residual stress layer and the maximum compressive residual stress are increased. Surface hardness is also increased. The fatigue strength is increased, but enhancement is no more than 5% because of the increase of surface roughness. Noticeably, all of the TC4 specimens after shot peening show inner crack initiations. Oxide inclusion is always the core of cracks, and the small crack propagation in crack initiation area acts as the slip of α-phase.

Precipitates formation and its impact in friction stir welded and post-heat-treated Inconel 718 alloy

2011 ◽  
Vol 1363 ◽  
Author(s):  
Kuk Hyun Song ◽  
Han Sol Kim ◽  
Won Yong Kim
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Inconel 718 ◽  
Rotation Speed ◽  
Base Material ◽  
Post Heat Treatment ◽  
Inconel 718 Alloy ◽  
Friction Stir ◽  
Heat Treated

ABSTRACTIn order to investigate the formation of precipitates such as MC carbides and intermetallic compounds in the friction stir welded and post-heat-treated Inconel 718 alloy, this work was carried out. Furthermore, the microstructural and mechanical properties of welds and post-heat-treated material were evaluated to identify the effect on precipitates formed during post-heat-treatment. Friction stir welding (FSW) was performed at a rotation speed of 200 rpm and welding speed of 150 mm/min; heat treatment was performed after welding at 720 °C for 8 hours in vacuum. As a result, the grain size due to FSW was notably refined from 5–20 μm in the base material to 1–3 μm in the stir zone; this was accompanied by dynamic recrystallization, which resulted in enhancements in the mechanical properties as compared to the base material. In particular, applying heat treatment after FSW led to improvements in the mechanical properties of the welds—the microhardness and tensile strength increased by more than 50% and 40% in fraction, respectively, as compared to FSW alone.

The Effect of Hybrid Surface Modification; Combination of Fine Particle Bombardment Treatment and Nitriding, on Fatigue Properties of Steel

2007 ◽  
Vol 353-358 ◽  
pp. 215-218
Author(s):  
Shoichi Kikuchi ◽  
Jun Komotori ◽  
Yutaka Kameyama ◽  
Kengo Fukazawa
Keyword(s):  
Residual Stress ◽  
Surface Modification ◽  
Fatigue Strength ◽  
Particle Bombardment ◽  
Fine Particle ◽  
Compressive Residual Stress ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Stress Distributions ◽  
Factor Α

In order to clarify the effects of the hybrid surface modification process; a combination of Fine Particle Bombardment (FPB) treatment and nitriding, on the fatigue properties of AISI 4135 steel (stress concentration factor: α=2.36), high cycle fatigue tests were carried out with a rotational bending machine at room temperature. Observations of fracture surfaces and measurements of hardness and residual stress distributions were carried out to investigate the fracture mechanism and fatigue strength. It was revealed that treating process sequence did affect residual stress distributions. Compressive residual stress generated at the surface of FPB treated specimen after nitriding was higher than that of the one FPB treated before nitriding. It was clarified that the higher the specimen hardness was, the higher compressive residual stress was generated at the surface. Therefore, FPB treatment after nitriding increased the fatigue strength of steel.

scholarly journals Grain Size Evolution and Mechanical Properties of Nb, V–Nb, and Ti–Nb Boron Type S1100QL Steels

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 492
Author(s):  
Jan Foder ◽  
Jaka Burja ◽  
Grega Klančnik
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Hot Forging ◽  
Size Control ◽  
High Strength ◽  
Fatigue Properties ◽  
Titanium Addition ◽  
Austenite Grain Size ◽  
Size Evolution

Titanium additions are often used for boron factor and primary austenite grain size control in boron high- and ultra-high-strength alloys. Due to the risk of formation of coarse TiN during solidification the addition of titanium is limited in respect to nitrogen. The risk of coarse nitrides working as non-metallic inclusions formed in the last solidification front can degrade fatigue properties and weldability of the final product. In the presented study three microalloying systems with minor additions were tested, two without any titanium addition, to evaluate grain size evolution and mechanical properties with pre-defined as-cast, hot forging, hot rolling, and off-line heat-treatment strategy to meet demands for S1100QL steel. Microstructure evolution from hot-forged to final martensitic microstructure was observed, continuous cooling transformation diagrams of non-deformed austenite were constructed for off-line heat treatment, and the mechanical properties of Nb and V–Nb were compared to Ti–Nb microalloying system with a limited titanium addition. Using the parameters in the laboratory environment all three micro-alloying systems can provide needed mechanical properties, especially the Ti–Nb system can be successfully replaced with V–Nb having the highest response in tensile properties and still obtaining satisfying toughness of 27 J at –40 °C using Charpy V-notch samples.

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