Search Results for metal penetration

The appearance, morphology, and extent of the casting skin are the consequence of mold-metal interface interaction. This article discusses the classification of the mold-metal interaction based on severity: mild mold-metal interaction and severe mold-metal interaction. The casting surface exhibits some roughness, which depends on the molding materials used in the casting process. The article describes the effects of the casting skin in spheroidal graphite (SG) and compact graphite (CG) irons, as well as the mechanism of casting skin formation. It discusses the physics of liquid metal penetration in sand molds and concludes with information on the effect of sand additives and mold coatings.

Solidification is a comprehensive process of transformation of the melt of metals and alloys into a solid piece, involving formation of dendrites, segregation which involves change in composition, zone formation in final structure of the casting, and microporosity formation during shrinkage. This article describes the imperfections in the solidification process including porosity, inclusions, oxide films, secondary phases, hot tears, and metal penetration. It talks about the purpose of the gating system and the risering system in the casting process.

Pitting is a form of localized corrosion that is often a concern in applications involving passivating metals and alloys in aggressive environments. This article describes the test methods for pitting corrosion. These methods include ASTM G 48, ASTM F 746, ASTM G 61, ASTM G 100, and electrochemical noise measurements. The visual examination, metallographic examination, and nondestructive inspection of pits are discussed. The article reviews the procedures for the use of standard charts, metal penetration, statistical analysis, and loss in mechanical properties to quantify the severity of pitting damage.

Casting offers the cost advantages over other manufacturing methods for most components. This article reviews the aspects of castings with which designers should be familiar, as well as the methods used by foundries to produce high-integrity castings. It discusses the design concepts that designers and foundries can use to obtain maximum performance from cast parts. The article describes the effects of casting discontinuities on properties, including porosity, inclusions, hot tears, metal penetration, and surface defects. A discussion on hot isostatic pressing treatment of castings is also provided. The article concludes with information on solidification simulation and its use in designing castings.

Melting with induction crucible furnaces (ICFs) is a well-established and reliable technology, and their maintenance must be performed at regularly scheduled intervals to ensure safe operation. This article discusses monitoring of the refractory lining, and presents an overview of the various wear-indication methods, namely, manual checks, ground leakage indication, evaluation of electrical values of the furnace, and temperature measurement. It also presents the working principle, physical restrictions, limitations, and remarks on these methods.

This article discusses the operation principles, advantages, limitations, process parameters, consumables or electrodes, the equipment used, process variations, and safety considerations of gas metal arc welding (GMAW). It reviews the important variables of the GMAW process that affect weld penetration, bead shape, arc stability, productivity, and overall weld quality. These include welding consumables, equipment settings, and gun manipulation. The major components of a GMAW installation such as a welding gun, shielding gas supply, electrode feed unit, power source, and associated controls are discussed.

Electroslag welding (ESW) and electrogas welding (EGW) are two related procedures that are used to weld thick-section materials in the vertical or near-vertical position between retaining shoes. This article discusses the fundamentals of the electroslag process in terms of heat flow conditions and metal transfer and weld pool morphology. It presents constitutive equations for welding current, voltage, and travel rate for ESW. The article describes the metallurgical and chemical reactions in terms of fusion zone compositional effects, weld metal inclusions, solidification structure, and solid-state transformations. It describes the electroslag process development and the applications of electroslag and electrogas processes. The article concludes with a discussion on weld defects, such as temper embrittlement, hydrogen cracking, and weld distortion.

Hybrid laser arc welding (HLAW) is a metal joining process that combines laser beam welding (LBW) and arc welding in the same weld pool. This article provides a discussion on the major process variables for two modes of operation of HLAW, namely, stabilization mode and penetration mode. The major process variables for either mode of operation include three sets of welding parameters: the variables for the independent LBW and gas metal arc welding processes and welding variables that are specific to the HLAW process. The article discusses the advantages, limitations, and applications of the HLAW and describes the major components and consumables used for HLAW. The components include the laser source, gas metal arc welding source, hybrid welding head, and motion system. The article also describes the typical sources of defects and safety concerns of HLAW.

Stress-corrosion cracking (SCC) is a form of corrosion and produces wastage in that the stress-corrosion cracks penetrate the cross-sectional thickness of a component over time and deteriorate its mechanical strength. Although there are factors common among the different forms of environmentally induced cracking, this article deals only with SCC of metallic components. It begins by presenting terminology and background of SCC. Then, the general characteristics of SCC and the development of conditions for SCC as well as the stages of SCC are covered. The article provides a brief overview of proposed SCC propagation mechanisms. It discusses the processes involved in diagnosing SCC and the prevention and mitigation of SCC. Several engineering alloys are discussed with respect to their susceptibility to SCC. This includes a description of some of the environmental and metallurgical conditions commonly associated with the development of SCC, although not all, and numerous case studies.

Electroslag welding (ESW) involves high energy input relative to other welding processes, resulting generally in inferior mechanical properties and specifically in lower toughness of the heat-affected zone. Electrogas welding (EGW) is a method of gas metal or flux cored arc welding, wherein an external gas is supplied to shield the arc, and molding shoes are used to confine the molten weld metal for vertical-position welding. This article describes the fundamentals, temperature relations, consumables, metallurgical and chemical reactions, and process development of ESW. The problems, quality control, and process applications of ESW and EGW are also discussed.

Total joint replacement in orthopedic surgery can be achieved by excision, interposition, and replacement arthroplasty. This article details the most common materials used in total replacement synovial joints: metals, ceramics, and ultrahigh molecular weight polyethylene (UHMWPE). The principal physical properties and tribological characteristics of these materials are summarized. The article discusses pin-on-disk experiments and pin-on-plate experiments for determining friction and wear characteristics. It explains the use of various types of joint simulators, such as hip joint simulators and knee joint simulators, to evaluate the performance of engineering tribological components in machine simulators. The article concludes with a section on the in vivo assessment of total joint replacement performance.

This article provides an overview of the types of weld discontinuities that are characteristic of specialized welding processes. These welding processes include electron-beam welding, plasma arc welding, electroslag welding, friction welding, resistance welding, and diffusion welding. The article also describes the common inspection methods used to detect these discontinuities.

Fluid flow is important because it affects weld shape and is related to the formation of a variety of weld defects in gas tungsten arc (GTA) welds. This article describes the surface-tension-driven fluid flow model and its experimental observations. The effects of mass transport on arc plasma and weld pool are discussed. The article reviews the strategies for controlling poor and variable penetration and describes the formation of keyhole and fluid flow in electron beam and laser welds. It also explains the fluid flow in gas metal arc welding and submerged arc welding, presenting its transport equations.