scholarly journals Operation-Oriented Studies on Wear Properties of Surface-Hardened Alloy Cast Steels Used in Mining in the Conditions of the Combined Action of Dynamic Forces and an Abrasive Material

2017 ◽  
Vol 62 (4) ◽  
pp. 2381-2389 ◽  
Author(s):  
A.N. Wieczorek
Keyword(s):  
Abrasive Wear ◽  
Shot Peening ◽  
Cast Steel ◽  
Operating Conditions ◽  
Dynamic Force ◽  
Cast Steels ◽  
Dynamic Forces ◽  
Combined Action ◽  
The Impact ◽  
Wear Tests

Abstract This paper presents the results of wear tests of shot-peened and not shot-peened cast steels used in the mining machinery industry, in particular in the construction of chain drums for armoured face conveyors. Wear tests were carried out in the conditions corresponding to the real operating conditions of armoured face conveyors during drifting work in rocks such as sandstone. The operating factors subjected to the analyses included the presence of quartz abrasive and the impact of external dynamic forces. On the basis of the wear tests as well as the microhardness and microstructure examinations performed, it has been found that the action of an additional dynamic force has a synergistic impact on the process of abrasive wear in loose quartz abrasive. It has been further found that the value of abrasive wear of chain wheels operated in the conditions of a combined action of abrasive and a dynamic force depends on whether the area of mating of wheels with the chain was shot-peened or not before the wear tests – an increase in the abrasive wear was observed for the wheels made of cast steel subjected to shot peening in the area of mating with the chain. Lower resistance to abrasive wear of the cast steels subjected to shot peening before the wear tests could result from the formation of cracks in the surface layer caused by the action of shot.

Experimental Studies on Abrasive Wear of Surface-Hardened and Shot Peened Alloy Cast Steels

2016 ◽  
Vol 674 ◽  
pp. 201-206
Author(s):  
Andrzej Norbert Wieczorek
Keyword(s):  
Abrasive Wear ◽  
Cast Steel ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Linear Wear ◽  
Plastic Properties ◽  
Cast Steels ◽  
Wear Tests ◽  
Alloy Cast

The paper presents the results of wear tests of shot-peened and non-shot-peened cast steels with the use of an especially designed test rig simulating real operating conditions of chain wheels. The chain wheels subjected to tests were operated with the use of loose quartz abrasive. The studies involved the determination of strength and plastic properties, hardness distributions, microstructure and linear wear of the selected cast steels. Based on the results obtained, the following was found: the abrasive wear of cast steel chain wheels increased after shot peening.

scholarly journals Abrasive Wear Properties of Fe-Based Alloys Designed for Mining Applications

2017 ◽  
Vol 62 (3) ◽  
pp. 1521-1534 ◽  
Author(s):  
A. N. Wieczorek ◽  
D. Myszka
Keyword(s):  
Abrasive Wear ◽  
Cast Steel ◽  
Volume Loss ◽  
Wear Properties ◽  
Abrasive Material ◽  
Initial Hardness ◽  
Loss Of Mass ◽  
The Impact ◽  
Quenching And Tempering ◽  
Wear Tests

AbstractThe purpose of this study was to determine experimentally the wear properties of 5 groups of iron-based alloys used in the mining and transport machines exposed to the action of a hard abrasive material. The groups of materials to be examined included austempered ductile irons (ADI), steels and cast steel designed for quenching and tempering and for surface hardening, hard-wearing hardened steels and structural steels. The wear tests were carried out on a disc-on-disc test rig. The test samples were examined under conditions of sliding mating, while the leading destructive process was microcutting of the surface with loose corundum grain. The loss of mass of the examined samples was measured as a parameter characterizing the wear. Base on it, other wear coefficients were determined, for example the volume loss, the intensity of wear and the wear rate. The volume loss values determined were presented as a function of the strength and the initial hardness. Based on the results obtained, it was found that the hardened steel and ADI had comparable wear properties, while the ADI surface was strengthened probably as a result of the transition of austenite into martensite and the impact of the deformation of the graphite contained in ADI on the abrasive wear of the surface.

Dynamic Analysis of Mechanical Systems With Clearances—Part 1: Formation of Dynamic Model

1971 ◽  
Vol 93 (1) ◽  
pp. 305-309 ◽  
Author(s):  
S. Dubowsky ◽  
F. Freudenstein
Keyword(s):  
Equations Of Motion ◽  
Operating Conditions ◽  
Coupled Systems ◽  
Dynamical Response ◽  
Dynamic Force ◽  
Dynamical Equations ◽  
Mechanical Joint ◽  
The Impact ◽  
Insight Into

A mathematical model of an elastic mechanical joint with clearances has been formulated and the dynamical equations of motion derived (Part I). The model, which we have called an Impact Pair, is basic to the determination of the dynamical response of mechanical and electromechanical systems with clearances, including determination of dynamic force amplification, frequency response, time-displacement characteristics, and other dynamic characteristics. Whenever possible, the results for the impact pair under various operating conditions are illustrated by graphs, which may also offer some insight into the behavior of clearance-coupled systems.

scholarly journals Effect of Mo Concentration on the Microstructure Evolution and Properties of High Boron Cast Steel

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 975
Author(s):  
Zhiguo Chen ◽  
Sen Miao ◽  
Lingnan Kong ◽  
Xiang Wei ◽  
Feihong Zhang ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Abrasive Wear ◽  
Microstructure Evolution ◽  
Cast Steel ◽  
Fish Bone ◽  
Solid Solution Strengthening ◽  
High Boron ◽  
Mo Content ◽  
High Boron Cast Steel ◽  
The Impact

The microstructure evolution, mechanical properties, and tribological properties of high boron cast steel (HBCS) with various Mo concentrations are investigated. The results indicate that Mo addition can significantly modify the microstructure and enhance the comprehensive properties. With the increase of Mo concentration, borides change from the original fish-bone Fe-rich and Cr-rich M2B to dendritic Fe-rich M2B, blocky and cluster-like Cr-rich M2B, and grainy Mo-rich M2B. The hardness of HBCS increases gradually with the increase of Mo content due to the solid solution strengthening and the refinement of M2B. It can be found that all the samples exhibit quasi-cleavage, but the impact toughness increases firstly and reaches the maximum value when the concentration of Mo is 2.10 wt.%, which is the result of the dispersive distribution of M2B rather than the original fish-bone M2B. Subsequently, the impact toughness begins to decrease as the concentration of Mo further increases because of the extensive formation of grainy Mo-rich M2B at the grain boundary. Meanwhile, the wear results reveal that the average friction coefficient and wear ratio decrease with the increase of Mo content, and the wear mechanism changes from abrasive wear and adhesive wear to abrasive wear when the concentration of Mo exceeds 2.10 wt.%.

Brush Seals Used in Steam Environments: Chronological Wear Development and the Impact of Different Seal Designs

2015 ◽  
Author(s):  
M. Raben ◽  
J. Friedrichs ◽  
J. Flegler ◽  
T. Helmis
Keyword(s):  
Abrasive Wear ◽  
Contact Force ◽  
Operating Conditions ◽  
Test Facility ◽  
Working Fluid ◽  
Two Stage ◽  
Blow Down ◽  
Frictional Contacts ◽  
Brush Seals ◽  
The Impact

During the last decades a large effort has been made to continuously improve turbomachine efficiency. Besides the optimization of the primary flow path, also the secondary flow losses have been reduced considerably, due to the use of more efficient seals. Brush seals, as a compliant contacting filament seal, have become an attractive alternative to conventional labyrinth seals in the field of aircraft engines as well as in stationary gas and steam turbines. The aim of today’s research related to brush seals is to understand the characteristics and their connections, in order to be able to make performance predictions, and to ensure the reliability over a defined operating period. It is known that inevitable frictional contacts lead to an abrasive wear on the rotor side as well as on the bristle side. The wear situation is essentially influenced by the resulting contact force at the seal-to-rotor interface during the operating time. This contact force depends on the seal’s blow down capability, which is mainly determined by the geometrical design of the bristle pack, e.g. the axial inclination of the investigated seal design, in combination with the design and material of the surrounding parts, as well as the thermal boundary conditions. For realistic investigations with representative circumferential velocities the TU Braunschweig operates a specially developed steam test rig which enables live steam investigations under varying operating conditions up to 50 bar and 450 °C. Wear measurements and the determination of seal performance characteristics, such as blow down and bristle stiffness, were enabled by an additional test facility using pressurized cold air up to 8 bar as working fluid. This paper presents the chronological wear development on both rotor and seal side, in a steam test lasting 25 days respectively 11 days. Interruptions after stationary and transient intervals were made in order to investigate the wear situation. Two different seal arrangements, a single tandem seal and a two-stage single seal arrangement, using different seal elements were considered. The results clearly show a continuous wear development and that the abrasive wear of the brush seal and rotor is mainly due to the transient test operation, particularly by enforced contacts during shaft excursions. Despite the increasing wear to the brushes, all seals have shown a functioning radial-adaptive behavior over the whole test duration with a sustained seal performance. Thereby, it could be shown that the two-stage arrangement displays a load shift during transients, leading to a balanced loading and unloading status for the two single brush seals. From load sharing and in comparison with the wear data of the tandem seal arrangement, it can be derived that the two-stage seal is less prone to wear. However, the tandem seal arrangement, bearing the higher pressure difference within one configuration, shows a superior sealing performance under constant load, i.e. under stationary conditions.

scholarly journals Influence of Shot Peening on Abrasion Wear in Real Conditions of Ni-Cu-Ausferritic Ductile Iron

2016 ◽  
Vol 61 (4) ◽  
pp. 1985-1990
Author(s):  
A. N. Wieczorek
Keyword(s):  
Surface Layer ◽  
Abrasive Wear ◽  
Ductile Iron ◽  
Shot Peening ◽  
Residual Austenite ◽  
Wear Properties ◽  
Surface Layers ◽  
Cast Irons ◽  
Dynamic Surface ◽  
The Impact

Abstract The paper presents results of the wear tests of chain wheels made of austempered ductile iron with various content of residual austenite. The aim of this study was to demonstrate the impact of the dynamic surface treatment (shot peening) on wear properties of surface layers of the chain wheels tested that were subjected to the action of quartz abrasive. Apart from determining the value of the abrasive wear, examinations of the magnetic phase content in the microstructure were carried out and plots of hardness of the surface layer as a function of the distance from the surface and microstructure of the materials were prepared. Based on the results, the following was found: an increase in the abrasive wear and a reduction in the hardness of the surface layer of chain wheels subjected to shot peening, as well as reduction of susceptibility to negative action of the shot for cast irons with the structure of upper ausferrite.

WEAR TESTING OF BUTTONS IN BITS FOR BLASTHOLE DRILLING

Tribologia ◽  
2018 ◽  
Vol 278 (2) ◽  
pp. 13-19 ◽  
Author(s):  
Rafał DUDEK ◽  
Krzysztof WŁADZIELCZYK
Keyword(s):  
Abrasive Wear ◽  
Blast Hole ◽  
Operating Time ◽  
Operating Conditions ◽  
Wear Testing ◽  
Hole Drilling ◽  
Drilling Process ◽  
Rock Mining ◽  
Drilling Rigs ◽  
The Impact

The article presents the results of the wear testing of buttons in selected types of bits with the diameter of 95 mm used for blast hole drilling in a rock mining. The purpose of the testing was to determine the type of the wear of peripheral and frontal buttons in the actual operating conditions of bits and the impact of selected parameters of the drilling process and of sharpening the buttons on their durability. Tests of button wear were carried out by the blasthole drilling in deposits of the Devonian and Triassic dolomites. For the blast hole drilling with tested bits, drilling rigs HSB 500 and HBM 60, equipped with down-the-hole impact mechanisms VKP 95-2 from the company Permon were used. Tests on the wear of buttons were carried out according to the adopted methodology, taking into account both their abrasive wear and wear through crushing or falling out. During the drilling of holes, every effort was made to use fixed values of parameters of the drilling process, except for the value of drill stem rotation speed, because one of objectives of the research was to determine its impact on the abrasive wear of tested bits buttons. The obtained results of tests proved that the predominant type of wear of button bits for blast hole drilling is an abrasive wear of frontal buttons, and regular sharpening of the buttons allows increasing the operating time of rock bits by up to 35%.

Usability of Boron as an Alloying Element in Gray Cast Iron Rollers and its Effect to Abrasive Wear Behaviour

2012 ◽  
Vol 445 ◽  
pp. 331-336
Author(s):  
Cemal Meran ◽  
Mehmet Yuksel
Keyword(s):  
Cast Iron ◽  
Wear Rate ◽  
Abrasive Wear ◽  
Gray Cast Iron ◽  
Operating Conditions ◽  
Gray Cast ◽  
Wear Behaviour ◽  
Sliding Speed ◽  
Abrasive Wear Behaviour ◽  
Wear Tests

In this study, usability of boron as an alloy element in gray cast iron and its effect to abrasive wear behaviour were investigated. Pin-on-drum wear tests at the room temperature carried out for seven low nickels alloyed gray cast irons with different boron addition. The mass losses, hardness values and microstructures for gray cast iron specimens with different boron alloyed were investigated for determining wear behaviour. The pin for the wear tests was manufactured from X210Cr12 cold work tool steel with material number of 1.2080. Abrasive pin-on-drum wear tests were carried out at a 165 N constant load and two different sliding speeds that are closely related to the appropriate operating conditions in rolling mills. The experimental studies have shown that wear rate decrease with increasing boron amount in chemical composition of the alloy and the wear rate at high sliding speed has decreased more rapidly than the rate at the low sliding speed with increasing boron amount.

scholarly journals Comparative Studies on the Wear of ADI Alloy Cast Irons as Well as Selected Steels and Surface-Hardened Alloy Cast Steels in the Presence of Abrasive

2017 ◽  
Vol 62 (1) ◽  
pp. 119-128 ◽  
Author(s):  
A. N. Wieczorek
Keyword(s):  
Operating Conditions ◽  
Linear Wear ◽  
Wear Properties ◽  
Cast Irons ◽  
Hardened Alloy ◽  
Cast Steels ◽  
Structural Applications ◽  
Alloy Steels ◽  
Wear Tests ◽  
Alloy Cast

AbstractThe paper presents the results of wear tests obtained for 4 groups of materials: surface-hardened alloy steels and alloy cast steels for structural applications, hard-wearing surface-hardened alloy cast steels, and austempered alloy cast irons. The wear tests have been performed on a specially designed test rig that allows reproducing the real operating conditions of chain wheels, including the rolling and sliding form of contact between elements. The chain wheels subjected to tests were operated with the use of loose quartz abrasive. This study presents results of measurements of material parameters, micro-structure of a surface subject to wear, as well as the linear wear determined for the materials considered. Based on the results, the following was found: the best wear properties were obtained for surface-hardened alloy steels and wear surface; strengthening of the ADI surface took place - most probably as a result of transformation of austenite into martensite; the uniformity of the structure of the materials affects the surface wear process. The study also indicated a significant degree of graphite deformation in ADI characterized by the upper ausferritic structure and its oblique orientation in relation to the surface, which resulted in a facilitated degradation of the surface caused by the quartz abrasive.

scholarly journals Abrasive Wear of Alloyed Cast Steels Applied for Heavy Machinery

2015 ◽  
Vol 15 (1) ◽  
pp. 99-104 ◽  
Author(s):  
A. Studnicki ◽  
M. Kondracki ◽  
J. Suchoń ◽  
J. Szajnar ◽  
D Bartocha ◽  
...  
Keyword(s):  
Abrasive Wear ◽  
Cast Steel ◽  
Heavy Machinery ◽  
Alloyed Cast ◽  
Cast Steels ◽  
Pin On Disc ◽  
Type Studies

Abstract In the paper the results and analysis of abrasive wear studies were shown for two grades of cast steels: low-alloyed cast steel applied for heavy machinery parts such as housing, covers etc. and chromium cast steels applied for kinetic nodes of pin-sleeve type. Studies were performed using the modified in Department of Foundry pin-on-disc method.

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