Surface Hardness Changes after Strengthening under Low-Amplitude Loads

2010 ◽  
Vol 97-101 ◽  
pp. 518-521
Author(s):  
Xi Lu ◽  
Ning Zhu
Keyword(s):  
Fatigue Limit ◽  
Surface Hardness ◽  
Front Axle ◽  
Experimental Results ◽  
Change Direction ◽  
Low Amplitude ◽  
Microstructure Of Material ◽  
Transmission Gear

This document investigated the changes of the surface hardness of the front axle and transmission gear after strengthening under low-amplitude loads below the fatigue limit (SLAL). The experimental results showed that the strength changes of the front axle after strengthening under low-amplitude loads was almost proportional to hardness, but it was inverse ratio for the transmission gear. There was no difference in the change direction of surface hardness, caused by strengthening or damaging. The reason of surface hardness changes could be due to that the microstructure of material was improved after being strengthening under low-amplitude loads below the fatigue limit.

Strengthening of transmission gear under low-amplitude loads

2008 ◽  
Vol 488 (1-2) ◽  
pp. 55-63 ◽  
Author(s):  
Lu Xi ◽  
Zheng Songlin
Keyword(s):  
Low Amplitude ◽  
Transmission Gear

scholarly journals Replication Experiments and Microstructural Evolution of the Ancient Co-Fusion Steelmaking Process

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1261
Author(s):  
Shangxiao Qiao ◽  
Wei Qian
Keyword(s):  
Carbon Content ◽  
Microstructural Evolution ◽  
Surface Hardness ◽  
Experimental Results ◽  
Steelmaking Process ◽  
Microstructural Characteristics ◽  
Simulation Experiments ◽  
History Of ◽  
Micro Analysis

The study of co-fusion was one of the essential topics in the history of metallurgy in China. Simulation experiments were an essential concept in the study of the co-fusion steelmaking process. This paper mainly studied the simulation experiments of co-fusion from two aspects: the replication of co-fusion swords by three different methods and the micro-analysis of the co-fusion samples. The experimental results indicated that several co-fusion swords could be made by different processes, but the carbon content and surface hardness were quite different. During repeated forge welding, the microstructure of the samples transformed from laminated to homogenized; finally, a steel with a uniform carbon content was obtained. It was challenging to determine the characteristics of co-fusion from the homogenized samples. The results prompt a rethinking of the microstructural characteristics of ancient co-fusion artifacts.

scholarly journals Research on calculation of grinding surface roughness

2022 ◽  
pp. 85-92
Author(s):  
Van Nga Tran Thi ◽  
Khanh Nguyen Lam ◽  
Cuong Nguyen Van
Keyword(s):  
Surface Roughness ◽  
Surface Hardness ◽  
Experimental Results ◽  
Grinding Wheel ◽  
Grinding Wheels ◽  
Machining Processes ◽  
Average Deviation ◽  
Proposed Model ◽  
Experimental Values ◽  
Tip Radius

In machining processes, grinding is often chosen as the final machining method. Grinding is often chosen as the final machining method. This process has many advantages such as high precision and low surface roughness. It depends on many parameters including grinding parameters, dressing parameters and lubrication conditions. In grinding, the surface roughness of a workpiece has a significant influence on quality of the part. This paper presents a study of the grinding surface roughness predictions of workpieces. Based on the previous studies, the study built a relationship between the abrasive grain tip radius and the Standard marking systems of the grinding wheel for conventional and superabrasive grinding wheels (diamond and CBN abrasive). Based on this, the grinding surface roughness was predicted. The proposed model was verified by comparing the predicted and experimental results. Appling the research results, the surface roughness when grinding three types of steel D3, A295M and SAE 420 with Al2O3 and CBN grinding wheels were predicted. The predicted surface roughness values were close to the experimental values, the average deviation between predictive results and experimental results is 15.11 % for the use of Al2O3 grinding wheels and 24.29 % for the case of using CBN grinding wheels. The results of the comparison between the predicted model and the experiment show that the method of surface roughness presented in this study can be used to predict surface roughness in each specific case. The proposed model was verified by comparing the predicted and measured results of surface hardness. This model can be used to predict the surface hardness when surface grinding

scholarly journals Development Research on Integrating CNC Machine Tool with Plasma for Online Surface Heat Treatment

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shao-Hsien Chen ◽  
Bo-Ting Wang
Keyword(s):  
Heat Treatment ◽  
Real Time ◽  
Feed Rate ◽  
Surface Hardness ◽  
Spindle Speed ◽  
Experimental Results ◽  
Machining Process ◽  
Cnc Machine ◽  
Optimum Parameters ◽  
Hardening Effect

In this study, the plasma was integrated with a lathe, and the online heat treatment was performed to achieve mechanical strength and hardness, to reduce the machining process and handling. However, for online heat treatment of cast iron FC25, it is important to study the parameters of the lathe and plasma, and the research method is used eventually to optimize the process and reduce the machining cost and machining error. The variable factors in the surface online real-time heat treatment are spindle speed, feed rate, and current, and the objective function is the hardness of mechanical properties. In the screening experiment, the interaction of factors was discussed using a full factorial experiment. The Central Composite Design was combined with the Lack-of-Fit test for the optimization experiment, and the R2 coefficient was used to determine whether the regression model is appropriate. The optimum parameters were derived from the contour diagram and response surface diagram. The experimental results show that the significant factors include spindle speed, feed rate, and current and the optimum parameters include spindle speed of 168 rpm, feed rate of 0.068 mm/rev, and current of 86 A. The experimental results of optimum parameters show that the surface hardness is increased from 306 HLD to 806 HLD and the surface hardening effect is enhanced by 163%, so the online real-time heat treatment equipment has the best hardening effect.

Effect of Scratch Depths on Fatigue Properties of PMMA for Aircraft Canopies

2014 ◽  
Vol 687-691 ◽  
pp. 81-84 ◽  
Author(s):  
Xin Hong Shi ◽  
Mei Juan Shan
Keyword(s):  
Fatigue Limit ◽  
Polymethyl Methacrylate ◽  
Fatigue Property ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Fatigue Properties ◽  
Scratch Depth

A series of fatigue tests is performed for polymethyl methacrylate (PMMA) specimens without scratches and with scratches. The scratch depth is set to be 0.2mm, 0.3mm and 0.4mm, respectively. Based on the experimental results, it can be deduced that contained fatigue limit of specimens with scratches significantly decreases compared to specimens without scratches. Besides, contained fatigue limit decreases gradually with scratch depth increasing from 0.0mm to 0.4mm. Consequently, it can be concluded that fatigue properties of PMMA will decrease when there exists scratch and for scratch depth from 0.0mm to 0.4mm, fatigue property decreases remarkably with deeper scratch.

Rapid calculation of the pressures and clearances in rough, rolling-sliding elastohydrodynamically lubricated contacts. Part 2: General, non-sinusoidal roughness

2007 ◽  
Vol 221 (5) ◽  
pp. 551-562 ◽  
Author(s):  
C J Hooke ◽  
K Y Li ◽  
G Morales-Espejel
Keyword(s):  
Decay Rate ◽  
Experimental Results ◽  
Wave Number ◽  
Lubricated Contacts ◽  
Pressure Distributions ◽  
Rapid Calculation ◽  
Profile Amplitude ◽  
Low Amplitude ◽  
Rough Rolling ◽  
Ehl Contact

Part 1 of this paper [1] described how the behaviour of low amplitude, sinusoidal roughness in elastohydrodynamically lubricated (EHL) contacts could be characterized by three complex quantities: attenuation of original profile, amplitude of complementary wave and its wave number and decay rate. This second part outlines how these results can be used to estimate, rapidly, the clearances and pressures in any rough EHL contact. The method is applied to a number of contacts for which accurate experimental results are available and it is shown that the process gives close estimates of the clearance and pressure distributions where the amplitude of the attenuated roughness is less than 50 per cent of the clearance and good indication of the behaviour of rougher surfaces.

On the Use of the Theory of Critical Distances to Estimate KIc and ∆Kth from Experimental Results Generated by Testing Standard Notches

2009 ◽  
Vol 417-418 ◽  
pp. 25-28
Author(s):  
Luca Susmel ◽  
David Taylor
Keyword(s):  
Fatigue Limit ◽  
Material Properties ◽  
Reliable Method ◽  
Threshold Value ◽  
Experimental Results ◽  
Plane Strain Fracture Toughness ◽  
Linear Elastic ◽  
Experimental Strategy ◽  
Strain Fracture ◽  
Elastic Fracture

The present paper is concerned with the use of the Theory of Critical Distances (TCD), applied in the form of the Point Method (PM), to estimate the range of the threshold value of the stress intensity factor, Kth, as well as the plane strain fracture toughness, KIc. In more detail, by reanalysing a large amount of experimental data taken from the literature, it is proved that Kth can successfully be evaluated through the plain fatigue limit and another fatigue limit generated by testing samples containing a known geometrical feature, whereas KIc is suggested here as being estimated by using experimental results generated by testing samples weakened by notches of different sharpness. The validation exercise summarised in the present paper fully confirms that the TCD is not only a reliable method suitable for performing the static and fatigue assessment of real components, but also an efficient experimental strategy capable of accurately estimating the classical Linear Elastic Fracture Mechanics (LEFM) material properties.

Increased Wear Resistance of Roller Bearings Using Me-C: H Coated Rollers

2000 ◽  
Vol 122 (4) ◽  
pp. 682-688 ◽  
Author(s):  
Ulf Olofsson ◽  
Hans Sjo¨stro¨m ◽  
Ulf Sjo¨din
Keyword(s):  
Wear Resistance ◽  
Fatigue Life ◽  
Coefficient Of Friction ◽  
Amorphous Carbon ◽  
Experimental Test ◽  
Thrust Bearing ◽  
Surface Hardness ◽  
Experimental Results ◽  
Contact Surfaces ◽  
Number Of Particles

The contact surfaces in a boundary lubricated spherical roller thrust bearing can change form due to sliding and particle generated wear. These form changes can seriously reduce the fatigue life of the bearings. An experimental test series has been performed where this effect was investigated in bearings with metal mixed amorphous carbon, Me-C: H, coated rollers that were tested against bearings with standard rollers. The experimental results show that while the bearings with standard rollers can fail due to wear, the bearings with coated rollers are at the same time almost unaffected by wear. Also the number of particles generated in the contact was significantly less when using coated rollers. There were twice as many self-generated particles when using a standard bearing compared with a coated bearing. The effect of the coating is discussed in terms of surface hardness, coefficient of friction and tribochemical phenomena. [S0742-4787(00)02004-X]

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