Hard Facing Research Articles

Reparation by Hard Facing of the Damaged Secondary Stone Crushers

The possibilities for reparation by hard facing of the damaged working parts - the hammers of the secondary stones crusher are investigated in this paper. The analyzed crusher is stationary and it belongs into a group of the process equipment aimed for producing the crushed stone. The produced stone is later used for manufacturing various construction materials like asphalt, concrete, etc. Wear of the crusher's working parts occurs during the exploitation due to operation with very hard materials. That wear is usually abrasive and of high intensity what causes failure of the working parts and consequently the machine's downtimes and appearance of various types of losses, primarily financial ones. To prevent that, and to reduce the downtimes as well, one uses reparation technologies, one of which is hard facing. The analysis of the mass losses of the hard faced parts, after certain number of hours of the crusher's field operation, is performed in this paper.

Enhanced surface properties of iron by in situ hard nickel coating

Abstract In the current study, hard facing nickel alloy powders were coated in situ on pure iron by uniaxial hot pressing under vacuum atmosphere to improve its hardness and wear properties. The nickel alloy powders were placed onto the iron powders within a graphite die and then sintered at 1000 °C under 40 MPa for 10 minutes. Hardness and wear properties were studied by using a Vickers hardness tester and a ball-on-disk tribometer, respectively. The wear rates of the samples were evaluated using a sliding velocity of 0.13 m × s−1 under normal loads of 20, 30, 40 and 50 N at room temperature. The interface layer between the nickel layer and pure iron substrate was also evaluated by scanning electron microscopy and energy dispersive spectroscopy. The results showed that sintered samples exhibited strong bonding at the interface. The hardness and wear properties of the materials increased effectively after nickel coating.

Aspects of the Welding of Bronze Br.A9Zh4N4Mts1 with Copper-Nickel Alloys

This articles examines the formation of high-quality joints between aluminum bronzes and copper-nickel alloys that contain different amounts of nickel. The joints are formed by explosion welding or hard-facing as part of the fabrication of products for chemicals production, gas engineering, shipbuilding, and other sectors of industry (reinforcement bars, heat exchangers, pipelines, etc.). A study is made of the effect of the nickel content of copper-nickel welding wires on crack formation in hard-faced metal, its structure, and its mechanical properties when aluminum-nickel bronze of grade Br.A9Zh4N4Mts1 is joined with copper-nickel alloys by argon-arc welding and hard facing. It is shown that the use of welding wires made of copper-nickel alloys with a nickel content of up to 18% guarantees the formation of high-quality crack-free joints with mechanical properties that are comparable to the properties of the lower-strength material which is used.

Weld Properties of Low Carbon Steel Using Shielded Metal Arc Welding

Welding is basic part of the most modern assembly and manufacturing operations. Shielded metal Arc Welding process has hard facing and fabrication job application due to low cost electrode, increasing alloy transfer efficiency and low dilution with substrate without losing production capacity. SMAW electrode is coated with metal mixture called flux, which on decompose produce gases to restrict weld contamination, generating deoxidizers to disinfect the weld. The choice of electrode for SMAW lies on a number of factors, like weld material, welding direction and the preferred weld properties. The present paper investigate the microstructure and hardness properties of the Low carbon steel pipe welded using shielded metal arc welding with different electrode combinations.

Impact of the hard facing technology and the filler metal on tribological characteristics of the hard faced forging dies

Subject review The forging dies are parts, which are operating at elevated temperatures, while simultaneously subjected to variable loads that can be compressive even impact and shear. Impact of the hard facing technology is very strong since varying of the hard facing parameters directly affects the output characteristics of the hard faced layers. The criterion for estimating that impact was based on results of performed tribological investigations. The tribological parameters that were monitored were the friction coefficient, the wear scar/trace width and the wear area of the hard faced layers, with the two different types of lubricants. Hard facing technology implied selection of the welding process, filler metals, preheating temperatures and other parameters of the hard facing process. The influence of the proposed hard facing technology was determined by monitoring hardness, microstructure and wear resistance of the executed joints after the hard facing and after tempering. The objective of this work was to establish the correlation between the selected hard facing technology, filler metals and applied heat treatment on mechanical and tribological characteristics of the executed hard faced layers.

A Proposed Fuzzy Logic based System for Predicting Surface Roughness when Turning Hard Faced Components

Hard-facing or hard-surfacing process is used for enhancing the service life of various machine parts by reshaping the worn out or eroded or corroded areas in them to improve their wear resistant properties. The hard-faced part contains rough, irregular and wavy surface, hence machining process is applied on them to get smooth finish and also to maintain the required dimension. The present paper is proposing a fuzzy logic based system to predict the surface roughness of a shaft like hard-faced component using some existing experimental data. Cutting speed (V), feed rate (fr) and depth of cut (DOC) are the three cutting parameters which have been considered here to optimize the surface roughness of a component subjected to hard-facing process.

Influence of Particle Fracture on the Slurry Abrasion Behavior of Weld Deposited Martensitic Steel

The life of the components used under slurry abrasion conditions is governed by the process variables, properties of the abrasive materials in the slurry and the material properties. Slurry wear, abrasion occurs in Extruders, pumps and pipe transport slurry of minerals and ores in mineral processing industries. In the present research, the effect of operating variables such as abrasive particle size and shape, slurry concentration and normal load on the abrasive slurry wear behavior of the weld deposit martensitic steel surface produced by the Manual Metal Arc Welding Hard facing process was conceded out. The testing was conceded out using the slurry abrasion test rig. The silica sand particles were used as the abrasive medium. The qualitative nature of wear pattern and morphology of the worn out surface was examined under scanning electron microscope (SEM). These features were correlated with operating parameters.

Residual stress and cracking behaviors of Cr13Ni5Si2 based composite coatings prepared by laser-induction hybrid cladding

Cr13Ni5Si2 based composite coatings were prepared by laser-induction hybrid cladding (LIHC). Residual stresses in the composite coatings were characterized by X-ray based layer-removal method, and dye penetrant testing was adopted to inspect cracks in the coatings. Results indicate that, LIHC not only can remarkably reduce residual stress in the composite coatings, but also can completely avoid cracks in the large area and high thickness hard facing coatings. Furthermore, a residual stress evolution model for the LIHC was established, and it reveals that temperature difference between the composite coating and the substrate is the main inducement that leads to residual stress, and dwell time of the coating in the temperature range of 800°C to 500°C (t8–5) is an important factor that affects residual stress releasing. Due to the hybrid effect of laser beam and induction heating, temperature difference between the coating and the substrate decreased, and t8–5 increased. As a result, residual stresses were decreased remarkably and cracks in the composite coatings were avoided.

BORATING OF SOLID PARTICLES COMPOSITE MATERIALS

Found that under most conditions of surfacing of composite materials (CM) is the dissolution of solid particles in a matrix with segregation on the surface section of the degradation products of metal and carbon, which has a negative impact on the durability of CM. There are several ways to reduce the dissolution of solid particles in a matrix of CM, one of which is the application of protective coatings. In the papers [2-5] studied the effectiveness of nickel-based protective coatings deposited on solids by precipitation, which is a costly method. In quality of a covering it is offered to use alloys on the basis of iron, nickel, cobalt. However such sheeting doesn’t lead to increase of wear resistance of CM as it is completely dissolved in the CM matrix at a high-temperature hard facing, significantly reducing its microhardness. Authors offered a way of drawing coverings by method of sedimentation of pine forest on firm particles that leads to increase of thermal stability and wear resistance of CM.

Reparation of damaged forging dies by hard facing (HF) technology

Reparation of damaged forging dies by hard facing (HF) technology

Influence of Tempering on the Deformation Level of the Multi-layer Hard Faced Samples

Res**ults of determination of the longitudinal, lateral and angular deformations in hard faced samples are presented in this paper, as well as the influence of the additional heat treatment on the level of residual deformations. Investigation assumed multi-layer hard facing of the two plates (thicknesses 7.4 and 29mm) made of steel 55CrMo8. Deformations were measured before the hard facing – after the plates’ preparation by grinding, immediately after hard facing and after tempering. The objective was to determine if and how much the additional heat treatment (tempering) influences the level of residual deformations in the hard faced joints.

Experimental Determination of Deformations of the Hard Faced Samples Made of Steel for Operating at Elevated Temperatures

An experimental procedure for determination of the lateral and longitudinal deformations of the multi-layer hard faced samples made of steel for operating at elevated temperatures is presented in this paper. Two plates, which were hard faced in three passes, were used to determine the level of residual stresses. The cored electrodes UTOP 38 and UTOP 55 were used. Deformations were measured in two phases: before and after the hard facing. The objective of deformations measurements was to establish the correlation between deformations, namely the applied technology (the input energy/heat) and the level of residual stresses, for different plate thicknesses.

MODIFIED HAGG & SANKEY METHOD TO ESTIMATE THE BALLISTIC BEHAVIOUR OF LIGHTWEIGHT METAL/COMPOSITE/CERAMIC ARMOUR AND A FUSELAGE SKIN OF AN AIRCRAFT

Hagg & Sankey method assesses the functionality of containment rings, which prevent perforation of an aircraft's elements from turbine engine disc fragments after disc burst. However, the method assumption was based on studies of mechanism of destruction of ballistic shields made of among others ceramics, by small arms bullets. The hard ceramic facing of the ballistic shield blunts the projectile and breaks up the projectile's hard core used for armour piercing. As an impact result, a conoid of finely pulverized ceramic dust is formed, absorbing energy in the formation process. The dust, containing the remnants of the projectile's energy hits the backing, but is now spread over a larger area. With backings made of fibre, energy is absorbed in stretching, breaking and delamination. With backings made of ductile metal, energy is absorbed in elastic deformation. Modification of the method consisted of taking into account the stratification of the ceramic-metal composite and the occurrence of an aircraft stiffened skin, in order to better assess the effectiveness of ballistic shields. The concept of estimating the resistance was based on the described destruction mechanism, where the object of analysis is a metal containment ring with an additional ceramic protective ballistic shield. A comparison of two scenarios- with and without an additional 2 mm aluminum alloy skin was taken into account. For this particular scenario, results were sufficient for both of the two analyzed endurance criteria.

Effect of Buffer Layer on Interface Bond Strength and Abrasive Wear of Hard Faced Cast Iron

Effect of Buffer Layer on Interface Bond Strength and Abrasive Wear of Hard Faced Cast Iron

Effect of Buffer Layer on Interface Bond Strength and Abrasive Wear of Hard Faced Cast Iron

The effect of five different buffer layers followed by a hardfacing electrode deposited on gray cast iron plate (ASTM grade 2500) upon performance of interface between substrate cast iron and deposited layers as well as abrasive wear behaviour of hardfaced deposits were studied. The results show that high nickel buffer electrode attributed best performance of interface bond in terms of shear strength and relatively lower nickel buffer electrode attributed best abrasive wear properties. The shear strength at the interfaces and wear properties has been correlated with microstructure and micro-mechanism of fracture in shear strain and micro-mechanism of metal removal in abrasive wear.

INFLUENCES OF VARIOUS PROCESS PARAMETERS ON FRICTION STIR PROCESSING ZONE IN ALUMINIUM ALLOYS

This paper presents a review of influence of process parameters on friction sir processing zone in aluminium alloys and suggesting a model for process parameters.Friction Stir processing is a process derived from friction welding whereby a coating material, in rod form is rotated under pressure, generating a plasticized layer in the rod at the interface with the substrate. By moving a substrate across the face of the rotating rod a plasticized layer between 0.2-2.5mm thick is deposited. The resulting composite material is created to provide the characteristics demanded by any given application. It is a technique for depositing many materials including tool steels, stainless steels and hard facings to improve the performance of an alloy. Friction Stir processing opens up a new area of repair and reclamation of worn and damaged components. Friction Stir processing form application of material to form a protection against wear and corrosion. Friction stir welding creates bonds through the combined effects of heat, deformation by a stirring action, and pressure using a non consumable tool that is translated along a joint line. Friction stir processing is a means to locally modify properties over depths or volumes that depend on the material being processed and the desired effect. Friction stir processing can dramatically refine grain structures producing improvements in a variety of properties. This review paper includes the influence of tool pin profile and tool shoulder diameter on the formation of friction stir processing zone, effect of tool position on the fatigue properties of dissimilar sheets joined by friction stir welding, Thermo-mechanical model with adaptive boundary conditions for friction stir welding.

To Study the Slurry Erosion Behaviour of Hard Faced Alloy SS304

Slurry erosion of impellers decreases the efficiency of impellers up to 5-10%. The slurry erosion depends upon many parameters viz. silt size, concentration, hardness of particles, velocity of water etc. In this research work the effect of these parameters has studied on the hard facing of SS 304 with hard alloy III and titanium alloy. It is found that hard facing helps to increase the erosion resistance properties of the substrate material.

Improving the Durability of Blast-Furnace Tuyeres

When blast furnaces are forced to run at high speed, one way of reducing their downtime, increasing their productivity, and lowering the cost of making pig iron is to improve the durability of the tuyeres. Experience shows that the main causes of tuyere failure are crack formation, wear, and burn-throughs. The durability of a tuyere and the type of problems encountered with it are significantly affected by the sophistication of the smelting technology that is used and the quality of the charge materials. Most tuyeres do not last longer than three months when the supply of raw materials to the furnace is unstable, and 20% of tuyeres (out of the total number that are replaced) have lasted less than half a month under such conditions. The amount of furnace downtime necessitated by the replacement of failed tuyere parts has reached 2.0–2.5% of nominal operating time, which has seriously hurt furnaces’ technical-economic indices. Stabilization of the operation of blast furnaces at EZRAZ ZSMK has allowed the combine to work on improving the durability of the tuyeres by redesigning them, improving the quality of the work done in making them, and applying protective coatings (by plasma deposition, electron-beam hard facing, etc.). The combine’s introduction of a new technology for making tuyeres and the strengthening of these pieces of equipment while ensuring a satisfactory cooling rate have made it possible to reduce the incidence of tuyere failure due to cracking. The number of tuyere replacements has declined during both normal and high-speed operation of the furnaces, which has in turn elevated tuyere service life to an average of 5–7 months and a maximum of 14–15 months.

A Fuzzy Logic Based Model to Predict Weld Width – A Case Study of Hard Facing Process Using MIG Welding on Dual Plate Check Valve

Welding input parameters play a very significant role in determining the quality of a weld joint. The joint quality can be defined in terms of weld-bead geometry. The 23 replication with 4 center points experiments are performed on non-return valve material WCB by varying various MIG Welding process parameters. Here welding current, welding speed and gas flow rate are considered as input parameters with two levels. A fuzzy model is developed to predict the weld width in context of these input parameters. Fuzzy model uses fuzzy expert rules, triangular membership function and centroid area method for defuzzyfication process using MATLAB fuzzy logic tool box. The developed model is validated by performing experiments at center points. The result shows prediction may lie in the range of 95.18-100%.

Variation in Residual Stresses due to Thermal Cycling Induced on the Hardfaced Grid Plate in PFBR

In sodium cooled fast breeder reactors, the high operating temperature necessitates hard facing of grid plate to avoid galling and to reduce the wear loss of the base material . Nickel-base cobalt-free alloy called Colmonoy-5 has been chosen as the hard facing material for the Prototype Fast Breeder Reactor (PFBR) grid plate. The grid plate (GP) which is a critical component made of 316 LN SS that holds the core subassemblies are hard faced, to prevent galling and also to minimize wear caused by subassembly insertion/removal and erosion due to high sodium velocity at 670 K. Thermal cycling of hard faced circular grid plate made by Plasma Transferred Arc Welding (PTAW) generates residual stresses due to differential shrinkage of the molten deposit and difference in coefficients of thermal expansion between the deposit and substrate material. In this project the effect of thermal cycling of a nickel-base hardfacing alloy deposited on an austenitic stainless steel grid plate was studied. Finite element analysis of hard faced circular grid plate is performed for obtaining residual stress which includes elasto-plastic analysis. Coupled thermo-mechanical analysis is done for thermal cycling of hardfaced circular gridplate to quantitatively estimate the residual stress.