Increasing wear resistance of the protective sleeve of the centrifugal pump made of gray cast iron by surface hardening

One of the weak spots that reduce the guaranteed operating time of centrifugal pumps is the assembly that includes the seal and protective sleeves. The main purpose of the bushings in the rotor kit is to protect the shaft from corrosion, erosion and wear. The sleeve operates under abrasive wear conditions by packing elements and abrasive particles that get into the liquid pumped by the pump. The protective sleeves made of gray cast iron do not meet the service life in connection with accelerated surface wear. Goal. The purpose of the work is to ensure high wear resistance of cast iron pump parts by heat treatment. Method. The chemical composition was determined on a portable laser analyzer Laser Z200 C +. The structure was studied using an optical microscope. The wear was investigated by the roller-block method on a friction machine. Surface quenching was carried out with a high-frequency lamp generator in a single-turn inductor. Results. The microstructure of gray cast iron as cast consists of pearlite, ferite, double phosphide eutectic and inclusions of lamellar graphite. Microhardness of small-lamellar pearlite is Н50 = 1550–2220 MPa, microhardness of phosphide eutectic is Н50 = 6500–8000 MPa. Surface induction quenching by high-frequency currents followed by low tempering is an effective way to increase the wear resistance of cast iron products of small cross-section and does not cause warping. Cast iron for surface quenching should have a pearlite structure, and graphite should be contained in the form of small inclusions. The optimal heating temperature for induction hardening was determined as 900 °С, which made it possible to obtain the microstructure of the hardened layer – martensite, double phosphide eutectic and graphite. Scientific novelty. The developed modes of surface quenching make it possible to preserve a double phosphide eutectic in the structure of the surface layer, which makes it possible to obtain high hardness and wear resistance of the hardened layer. Practical significance. Surface induction quenching with low tempering of cast gray iron increased its wear resistance by 2,4 times. The previous normalization had practically no effect on the durability of cast iron, since its structure contains less than 10% ferrite.

MEEHANITE GE200

Meehanite GE200 is an intermediate-tensile-strength gray cast iron that has a minimum tensile strength of 200 MPa (29 ksi), when determined on test pieces machined from separately cast, 30 mm (1.2 in.) diameter test bars. This material is generally used for smaller parts with wall thicknesses above 5 mm (3/16 in.). It has excellent fluidity, no tendency towards hard edges and a uniformly fine structure with small proportions of ferrite and is, therefore, readily machinable. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on casting, heat treating, machining, and joining. Filing Code: CI-87. Producer or source: Meehanite Metal Corporation.

Tribological Behavior and Surface Characterization of Gray Cast Iron-EN31 Steel under Lubricated Sliding Conditions

This research investigates the tribological behavior of gray cast iron against EN31 steel under lubricated conditions. The most typical lubricated sliding phenomena are the reduction of wear on both the sliding surfaces and any one of the critical surfaces. Static and hydrodynamic wear can be reduced based on fluid properties or the accessibility of fluid between the surfaces. The oil’s viscosity or content of the hydrocarbon and additives present in the oil plays a major role in controlling the wear of reciprocating surfaces. Therefore, this research work focused on metal-to-metal contact wear under the influence of lubricating oil (40 pride oil). The Taguchi method was used to select the sliding parameter combinations. Lubricated sliding resulted in a relatively reduced order of friction coefficient, attributable to better load distribution due to the formation of the lubricant film.

EFFECT OF COOLING RATE ON MICROSTRUCTURE AND HARDNESS IN GRAY CAST IRON CASTING PROCESS

This study aims to investigate the thermal conditions of the molds, changes in microstructure and hardness of casting products using sand mold and permanent mold. The use of sand mold and permanent mold results in different cooling rates. Thermal analysis was performed using a thermocouple to obtain a temperature versus time curve. Metallographic observations were carried out using a Scanning Electron Microscope equipped with Energy-Dispersive X-ray Spectroscopy. The Vickers hardness test was carried out in three areas with different thicknesses. The results showed a constant temperature at 691 oC where the eutectoid phase reaction occurred. Testing with sand mold showed that cast iron with flake graphite was finer and spreader than graphite in cast iron produced by permanent mold. Meanwhile, gray cast iron from a casting process with a permanent mold has a higher hardness than gray cast iron from a casting process using a sand mold.

WELDING ANALYSIS OF GRAY CAST IRON ASTM A48 CLASS 40 USING SMAW

The mechanical and physical characteristics of gray cast iron are intricately bound to its application as an essential material in manufacturing various goods. SMAW (Shielded Metal Arc Welding) is the most simple and widely used electric arc welding method. In this work, ASTM A48 gray cast iron Class 40 was joining using the SMAW method with the welding position used was 1G or underhand position. The joining used is the Butt Joint using an open Singel V seam with a current of 120A. The joining of Welding was characterized through dye penetrant and hardness tests. Rockwell hardness tests on base metal and heat affected zone reveal that the heat affected zone has the highest hardness value of 56.5 HRC, while the base metal has the lowest hardness value (41 HRC). Graphite, pearlite, and pearlite were all visible in the microstructure study.

Effect of Mechanical Vibration on Microstructure and Mechanical Properties of Gray Cast Iron in Lost Foam Casting

In order to reveal the effect of vibration solidification on microstructure and properties of gray cast iron in lost foam casting, Y-shaped HT100 gray cast iron was prepared by vibration lost foam casting, and the effect of amplitude on the microstructure and properties of gray cast iron was studied. The results showed that, with the increase in amplitude, the short and thin A-type flake graphite increases, and the austenite structure transforms from columnar to cellular. The hardness, tensile strength, and elongation of gray cast iron first increase and then decrease with the increase in amplitude. The appropriate amplitude in the process of Y-shaped HT100 gray cast iron by lost foam casting is 2 mm, while the tensile strength and elongation of gray cast iron are the highest, with the values of 147.51 MPa and 1.17%, respectively. The change of mechanical properties of gray cast iron is mainly determined by the morphology and distribution of austenite in gray cast iron and A-type flake graphite.