scholarly journals Fatigue strength of sintered and heat treated compacts made from composite-type alloyed steel powder.

1991 ◽  
Vol 38 (1) ◽  
pp. 18-21
Author(s):  
Osamu Furuki ◽  
Koji Yano ◽  
Shigeaki Takajo
Keyword(s):  
Fatigue Strength ◽  
Steel Powder ◽  
Alloyed Steel ◽  
Composite Type ◽  
Heat Treated

scholarly journals Development of Molybdenum Hybrid-Alloyed Steel Powder for High Fatigue Strength Sintered Parts

2010 ◽  
Vol 57 (5) ◽  
pp. 341-347
Author(s):  
Shigeru Unami ◽  
Yukiko Ozaki ◽  
Tsutomu Ushirozako ◽  
Hitoshi Tanino
Keyword(s):  
Fatigue Strength ◽  
Steel Powder ◽  
Alloyed Steel ◽  
High Fatigue

Rolling Contact Fatigue Property of Sintered and Carburized Compacts Made of Molybdenum Hybrid-Alloyed Steel Powder

2007 ◽  
Vol 534-536 ◽  
pp. 713-716 ◽  
Author(s):  
Shigeru Unami ◽  
Yukiko Ozaki ◽  
Satoshi Uenosono
Keyword(s):  
Fatigue Strength ◽  
Pore Structure ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Fatigue Property ◽  
Steel Powder ◽  
Rolling Contact ◽  
Alloyed Steel ◽  
Sintered Compact ◽  
Contact Fatigue Strength

A new molybdenum hybrid-alloyed steel powder has been developed. The powder is based on a molybdenum prealloyed steel powder to which molybdenum powder particles have been diffusion bonded. The sintered compact made of the developed powder has a finer pore structure than that of the conventional molybdenum prealloyed steel powder, because the ferritic iron phase (α-phase) with a high diffusion coefficient is formed in the sintering necks where molybdenum is concentrated resulting in enhanced sintering. The rolling contact fatigue strength of the sintered and carburized compacts made of this powder improved by a factor of 3.6 compared with that of the conventional molybdenum prealloyed steel powder. The improvement in the rolling contact fatigue strength should result from the fine pore structure without coarse pores acting as stress concentration points.

Improvement of Machinability of Sintered Composite-type Alloyed Steel Powder

1997 ◽  
Vol 119 (4A) ◽  
pp. 529-536
Author(s):  
Katsumi Yamaguchi ◽  
Takeshi Nakamoto ◽  
Masayuki Kitano ◽  
Masakuni Suzuki ◽  
Petros A. Abraha
Keyword(s):  
Tool Life ◽  
Cutting Tool ◽  
High Strength ◽  
Steel Powder ◽  
Alloyed Steel ◽  
Protective Film ◽  
Iron Particles ◽  
Electron Probe Microanalyzer ◽  
Sintered Composite ◽  
Composite Type

Composite-type alloyed steel powder has drawn great attention in recent years due to the rapid increase of high strength materials. A typical powder consisting of iron with nickel and molybdenum as an additive which adheres to the surface of iron particles is used. This type of sintered alloyed steel causes excessive tool wear. The purpose of this study is to improve the machinability of the sintered alloyed steel by adding nonmetallic materials. Experiments show that the addition of 3% glass to the sintered alloyed steel increases the tool life 100 times. In order to clarify the mechanisms of the increase of tool life, the worn face of the cutting tool is examined by an Electron Probe Microanalyzer (EPMA). The analysis shows that the glass additive acts as a protective film and lubricant when cutting with silicon nitride and tungsten carbide tools, respectively.

scholarly journals Errata: Properties of Rolled and Carburized Sintered Gear Made of Ni–Mo Pre-alloyed Steel Powder

2015 ◽  
Vol 62 (4) ◽  
pp. 217
Author(s):  
Satoshi NISHIDA ◽  
Masaki YOSHIDA ◽  
Hironori SUZUKI ◽  
Teruie TAKEMASU ◽  
Takao KOIDE
Keyword(s):  
Steel Powder ◽  
Alloyed Steel

scholarly journals Microstructural Characterization Of Laser Heat Treated AISI 4140 Steel With Improved Fatigue Behavior

2015 ◽  
Vol 60 (2) ◽  
pp. 1331-1334 ◽  
Author(s):  
M.C. Oh ◽  
H. Yeom ◽  
Y. Jeon ◽  
B. Ahn
Keyword(s):  
Fatigue Strength ◽  
Alloy Steel ◽  
Microstructural Evolution ◽  
Fatigue Behavior ◽  
Microstructural Characterization ◽  
Optical Microscope ◽  
Heat Treated ◽  
Aisi 4140 ◽  
Ultrasonic Fatigue

Abstract The influence of surface heat treatment using laser radiation on the fatigue strength and corresponding microstructural evolution of AISI 4140 alloy steel was investigated in this research. The AISI 4140 alloy steel was radiated by a diode laser to give surface temperatures in the range between 600 and 800°C, and subsequently underwent vibration peening. The fatigue behavior of surface-treated specimens was examined using a giga-cycle ultrasonic fatigue test, and it was compared with that of non-treated and only-peened specimens. Fatigue fractured surfaces and microstructural evolution with respect to the laser treatment temperatures were investigated using an optical microscope. Hardness distribution was measured using Vickers micro-hardness. Higher laser temperature resulted in higher fatigue strength, attributed to the phase transformation.

Modeling of Fatigue Slip Bands and Application to Notch Fatigue Problems

2008 ◽  
Author(s):  
Hiroshi Matsuno
Keyword(s):  
Fatigue Strength ◽  
Slip Band ◽  
Equivalent Stress ◽  
Cyclic Stress ◽  
Empirical Equations ◽  
Fundamental Idea ◽  
Slip Bands ◽  
Heat Treated ◽  
Fatigue Data ◽  
Stress Ratios

In the present paper, equivalent stress ratios (REQ-ratios), which have been proposed as parameters for correspondence between cyclic stress conditions of notched and unnotched specimens, are reviewed. The REQ-ratios are formulated based on a concept of plastic adaptation hypothesized for a fatigue slip band from a viewpoint of macro-mechanics. A method for diagramming fatigue strength of metals based on the parameter of the REQ-ratios is newly proposed. The method diagramming together the fatigue strength of notched and unnotched specimens is applied not only to fatigue problems of usually annealed, normalized and heat-treated materials but also to those of severely heat-treated and surface-treated ones. Fatigue strength diagrams are characterized with two types of fatigue strength: σw1 and σw2. The character of σw2 appears not only in specimens with sharp notches but also in unnotched specimens fatigue-tested at lower RN-ratios. Criteria on fatigue strength σw1 and σw2 are derived from the fatigue strength diagrams and formulated as empirical equations. Characteristics of fatigue slip bands are reviewed and two types of fatigue mechanisms are proposed related with fatigue strength σw1 and σw2 from a viewpoint of micro-mechanics. Consequently, it is found that the hypothesis of plastic adaptation is a very useful and fundamental idea for modeling a fatigue slip band and also for analyzing fatigue data of practical metals and alloys.

scholarly journals Residual Stresses Induced by Surface Working and Their Improvement by Emery Paper Polishing

2020 ◽  
Vol 4 (2) ◽  
pp. 21
Author(s):  
Makoto Hayashi
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Diffraction Method ◽  
304 Stainless Steel ◽  
Heat Treated ◽  
Emery Paper ◽  
Type 304 ◽  
Type 304 Stainless Steel

In many of machine parts and structural components, materials surface would be worked. In this study, residual stresses on the surfaces were measured by X-ray diffraction method, and effects of surface working on the residual stresses were examined. In case of lathe machining of type 304 stainless steel bar, the residual stresses in circumferential directions are tensile, and those in axial directions are almost compressive. Highly tensile residual stresses in the circumferential directions were improved by emery paper polishing. 10 to 20 times of polishing changes high tensile residual stresses to compressive residual stresses. In the case of shot peening on a type 304 stainless steel plate, the compressive residual stress inside is several hundred MPa lower than that on the surface. By applying the emery paper polishing to the shot peened surface 10 or 20 times, the residual stress on the surface is improved to −700 MPa. While fatigue strength at 288 °C in the air of the shot peened material is 30 MPa higher than solution heat treated and electro-polished material, the fatigue strength of the shot peened and followed by emery paper polished material is 60 MPa higher. Thus, the emery paper polishing is simple and a very effective process for improvement of the residual stresses.

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