Vacuum Hardening Research Articles

Identification of the critical activity in heat treatment process using TISM

The heat treatment process (HTP) is crucial in the manufacturing of any component, also the activities concerned with the heat treatment process are often subject to hazards. When the data related to industrial accidents are analyzed, it is identified that most of the industrial accidents have occurred because of HTP. Considering this, this research work intends to identify, analyze, and prioritize the activities carried in the HTP based on the nature of hazards. To identify the various activities carried out in the HTP and to understand the nature of hazards involved, a study was carried out in gear manufacturing company located in western Tamilnadu, India. Eighteen activities carried in the HTP are identified. Then, the total interpretive structural modeling (TISM) method is used to analyze the various activities. In the TISM method, the obtained results are generally arranged in hierarchical order, and the activity at the bottom of the hierarchy need to be addressed immediately. Next, MICMAC analysis is performed to understand the relationship between the activities. In our case, the activating finishing process, tempering, vacuum hardening process, and nitriding case hardening process are at the bottom level, and these activities need to be addressed in a short time. In MICMAC analysis, out of the 18 activities, 4 comes under the autonomous category, 3 comes under the dependent category, 6 comes under the linkage category, and 5 comes under the independent category. Based on the results obtained, some practical managerial implications are suggested for the mangers and practitioners involved in the heat treatment process.

Metallographic Examinations Performed on Automotive Parts Through Several Case Studies

Abstract Metallurgical analysis is widely used in the field of heat treatment of metals to ensure the quality of the treatments carried out on a wide variety of industrial parts and treatments carried out. It is therefore a valuable tool for subcontractors of the heat treatment industry to monitor their production and treatment response on various parts. Through different examples, we will present actual cases that involve in particular automotive parts. We show that there is a strong interdependence between material and heat treatment, one being related to each other, a successful treatment depends both on the metallurgical quality of the material and the production quality of the heat treatment process. We will discuss the type of treatments like: vacuum hardening or under protective atmosphere, surface induction hardening, carburizing, nitriding and brazing.

Effect of Deep Cryogenic treatment on AISI A8 Tool steel & Development of Wear Mechanism maps using Fuzzy Clustering

Tool steels are widely classified according to their constituents and type of thermal treatments carried out to obtain its properties. Viking a special purpose tool steel coming under AISI A8 cold working steel classification is widely used for heavy duty blanking and forming operations. The optimum combination of wear resistance and toughness as well as ease of machinability in pre-treated condition makes this material accepted in heavy cutting and non cutting tool manufacture. Air or vacuum hardening is recommended as the normal treatment procedure to obtain the desired mechanical and tribological properties for steels under this category.In this study, we are incorporating a deep cryogenic phase within the conventional treatment cycle both before and after tempering. The thermal treatments at sub zero temperatures up to -195°C using cryogenic chamber with liquid nitrogen as medium was conducted. Micro structural changes in its microstructure and the corresponding improvement in the tribological and physical properties are analyzed. The cryogenic treatment leads to more conversion of retained austenite to martensite and also formation of fine secondary carbides. The microstructure is studied using the micrographs taken using optical microscopy.The wear tests are conducted on DUCOM tribometer for different combinations of speed and load under normal temperature. The wear rates and coefficient of friction obtained from these experiments are used to developed wear mechanism maps with the help of fuzzy c means clustering and probabilistic neural network models. Fuzzy C means clustering is an effective algorithm to group data of similar patterns. The wear mechanisms obtained from the computationally developed maps are then compared with the SEM photographs taken and the improvement in properties due to this additional cryogenic treatment is validated.

Effect of Cryogenic treatment on VIKING cold working tool steel and development of wear mechanism maps

Tool steels are classified according to their alloying constituents and will exhibit their real properties upon proper thermal treatment. The process and sequence of heat treatment differ depending upon the percentage of carbon and other metallic elements. VIKING a special purpose tool steel coming under AISI A8 cold working steel classification is widely used for heavy duty blanking and forming operations because of its high wear resistance and equally good toughness. Air or vacuum hardening is recommended as the conventional heat treatment process for steels under this category. These steels are easily machinable in pretreated conditions and will get converted to hardened structure upon appropriate treatment. In this study, we are incorporating a shallow cryogenic cycle within the conventional treatment process before tempering. The thermal treatments at sub zero temperatures up to -90°C was conducted with liquid nitrogen as cryogenic medium and the changes in its microstructure and corresponding improvements in the tribological properties are analyzed. The microstructure is studied using the micrographs taken using optical microscopy which shows more pronounced martenstic conversion and formation of fine carbides. The treated material specimens are then subjected to wear tests on DUCOM TRIBOMETER for different combinations of speed and load under normal temperature without any lubrication. The wear rate and coefficient of friction obtained from these set of experiments are used to develop wear mechanism maps with the help of FUZZY C MEANS clustering. The wear mechanisms maps generated with this computational technique is then compared with the SEM photographs taken and the improvement in properties due to this additional cryogenic treatment is validated. XRD analysis was also performed to identify the phases present before and after cryogenic treatment.

TOOL STEEL WEAR RESISTANCE EVALUATION PRODUCED BY POWDER METALLURGY, HEAT TREATED VACCUM

Determination of wear rate is fundamental to life estimation tools heat treated, used in metal forming processes for the metalworking industry. Thus, the main purpose of this article is to determine the five types of wear rate of tool steel produced by powder metallurgy and one by conventional casting, heat-treated by vacuum hardening process, and triple tempered. To this end, we used the test method "pin and drive", which was used for testing three specimens for two different surface finishes (ground and polished) and 10N test load. The results showed that the wear rate will change for different surface finishes studied. It is suggested for further work can be measured the effect of different loads test tool steels, as well as engineering tested coatings on the surface of these materials.

Effect of Sintering and Heat Treatment Conditions on Mechanical Properties of Martensitic Stainless Steel Fabricated by MIM Process

The effects of sintering and heat treatment conditions on the mechanical properties of martensitic stainless steel fabricated by MIM process were investigated. The specimens were made by injecting the mixture of gas-atomized powders of 5 μm and 10 μm in mean particle diameter and a polymer binder into a metallic mold. The injection molded compacts were debound in air at 593 K for 7.2 ks. They were sintered in vacuum at temperatures between 1273 K and 1623 K for 7.2 ks. And the specimens were aged at various temperatures between 373 K and 873 K after vacuum hardening. The density of the as-sintered compact of 5 μm powder was higher than that of the as-sintered compact of 10 μm powder. In case of the as-sintered compact of 5 μm powder, the tensile strength corresponded to the change in density well, and the tensile strength of the compact sintered at 1373 K was 1600 MPa. On the other hand, in the case of the as-sintered compact of 10 μm powder, the tensile strength was rather lower than that of the as-sintered compact of 5 μm powder because of coarsening of the grain size. The tensile strength and elongation of the heat-treated compact of 5 μm powder were 1800 MPa and 12 %, respectively. The tensile strength and elongation of the heat-treated compact of 10 μm powder were 1680 MPa and 10 %, respectively. Thus, the mechanical properties of the compacts were approximately equal to those of the wrought material.

Using Preheated Inactive Gas for Vacuum Hardening and Isothermal Heat Treatment after Carburizing

Using Preheated Inactive Gas for Vacuum Hardening and Isothermal Heat Treatment after Carburizing

The Effect of Cryogenic Treatment on the Properties of AISI D2

The tool steel AISI D2 is usually processed by vacuum hardening followed by multiple tempering cycles. Deep cold treatment in between the hardening and tempering processes could reduce processing time and improve the final properties. Blocks of AISI D2 were vacuum hardened from different austenitizing temperatures. The hardened blocks were then subjected to various combinations of single and multiple tempering steps (520 and 540°C) and deep cold treatments (−90,− 120, and − 150°C). The results showed that for all austenitizing temperatures a single deep cold treatment followed by a single tempering cycle was sufficient to reduce the retained austenite to below 1%.

The effect of some heat treatment parameters on the dimensional stability of AISI D2

The tool steel AISI D2 is usually processed by vacuum hardening followed by multiple tempering cycles. It has been suggested that a deep cold treatment in between the hardening and tempering processes could reduce processing time and improve the final properties and dimensional stability. Hardened blocks were then subjected to various combinations of single and multiple tempering steps (520 and 540 °C) and deep cold treatments (−90, −120 and −150 °C). The greatest dimensional stability was achieved by deep cold treatments at the lowest temperature used and was independent of the deep cold treatment time.

Laser treatment of powder high-speed steels with prior vacuum hardening and surface impregnation

Laser treatment of powder steels R0M6F3-MP, R6M5-MP, and R6M5-P preliminarily subjected to vacuum quenching or vacuum cyanidation with quenching promotes the formation of surface layers having an elevated wear resistance under contact-abrasive action, for example, in machining ceramic and refractory heat-resistant materials or under the surface action of ion-plasma jets of a high specific power. The structure of laser-hardened surface layers consists of pseudo-acicular martensite and an elevated amount of finely dispersed carbides, which prevents spalling and chipping of thin functional edges in blades for continuous machining under cyclic thermal loads.

Erfahrungen beim Vakuumhärten mit Hochdruckgasabschreckung

The vacuum hardening combined with a high-pressure gas quenching offers a number of advantages compared with classical heat-treatment technologies. For hardening of heat-treatable steels the 800/500°C-time is decisive. Practicable cooling gases are nitrogen and helium. Experimental results of hardening different steels in gas stream are presented. In addition to that influence factors on the cooling period were examined: the choice and pressure of the cooling gas or the position in the apparatus. For hardening in the high-pressure gas stream a check of the optimal austenitization conditions is recommendable. The results of experiments are a contribution to a suitable and cost-effective choice of austenitization and cooling conditions for special fields of application.

Process of vacuum hardening of cutting and sharpening tools of high-speed steels in belt furnaces

The technical possibilities of vacuum elevator and bell furnaces commonly used for brazing and annealing precision parts in instrument-making and electronics can be widened. Small thin-blade tools of powder steels R6M5-P, 10R6M5-MP and “silver” steels R6M5, R6M5K5 with a minimum tolerance for sizing after hardening at a low cooling rate have high operational properties. The present paper is devoted to the process of heat treatment of special tools of the listed steels used to cut and shape ribbons, rods, and foils of alloys 36NKhTYu, 29NK, BrB2 in vacuum bcil furnaces under conditions of batch and small-batch production in electrical-engineering enterprises.

Structure of steel Kh12MF after vacuum hardening

1. The vacuum hardening of steel Kh12MF components with neutral-gas cooling makes it possible to improve the quality of the surface and reduce deformation significantly. 2. As compared with the structure after oil quenching, the microstructure of steel Kh12MF after vacuum hardening with a neutral gas is distinguished by improved etchability of the austenitic-grain boundaries. This effect is associated with slow cooling in the austenitic temperature interval during hardening. 3. The effect of improved etchability of the grains disappears after complete melting of the residual austenite during high-temperature tempering.

THYROPLAST 2083 and THYROPLAST 2083 SUPRA ESR

Abstract Thyroplast 2083 and 2083 SUPRA ESR steels are double tempered after a vacuum hardening treatment to develop a high hardness with excellent toughness. Vacuum degassing and ESR remelting assure superior cleanliness. High strength to 300 KSI is attainable. This datasheet provides information on composition, physical properties, and hardness as well as fracture toughness. It also includes information on corrosion resistance as well as heat treating, machining, and surface treatment. Filing Code: TS-515. Producer or source: Thyssen Specialty Steels Inc.

Universal Vacuum Hardening Plant Application and Results

Universal Vacuum Hardening Plant Application and Results

Torvac Passes the Test

PLESSEY Aerospace at Titchfield, Hants has installed a Compact 100 vacuum furnace from Cambridge‐based suppliers Torvac. The furnace has just completed the warranty year in operation on a wide range of heat treatments, brazing and degassing applications. The work is generally carried out to the full rigors of aerospace standards including mSR 953, CAA DAI/7591/65 and STAN 05/21. Typical of the jobbing work is the vacuum hardening of bevel gear box components which Plessey manufacture for the AV8B engines used in the Harrier jump jet.

Mathematical models of phase transformations and shape variations in a mechanical component during high vacuum hardening

The present paper deals with the mathematical models defined and adopted tostimulate the phase transformation processes and the shape variations in samples of different tool steels subjected to hardening in high vacuum furnaces. The results, which are obtained by numerical simulation, are compared with the corresponding experimental data.

Vacuum quenching of bearing races of steel 95Kh18

1. Hardening of bearing parts of stainless steel 95Kh18-Sh with heating in vaccum and cooling in nitrogen (99.996%) with forced circulation produces a bright surface with no trace of oxidation or decarburization. 2. Vacuum hardening ensures high corrosion resistance and reduces distortion of the parts.