Microstructure and Mechanical Properties of Maraging Steel 300 After Selective Laser Melting

Selective laser melting (SLM) is an additive manufacturing process for the direct fabrication of prototypes, tools and functional parts. The process uses a high intensity laser beam to selectively fuse fine metal powder particles together in a layer-wise manner by scanning cross-sections generated from a three-dimensional CAD model. The SLM process is capable of producing near fully dense functional products without almost any geometrical limitation and having mechanical properties comparable to those produced by conventional manufacturing techniques. There is a wide range of materials that are suitable to be processed by SLM including various steels, Ti, Al and CoCr alloys. Being one of these materials, maraging steel 300 (18Ni-300) is an iron-nickel steel alloy which is often used in applications where high fracture toughness and strength are required or where dimensional changes have to remain at a minimal level, e.g. aircraft and aerospace industries for rocket motor castings and landing gear or tooling applications. To achieve its superior strength and hardness, maraging steel, of which the name is derived from ‘martensite aging’, should be treated with an aging heat treatment. In this study, the effect of the SLM parameters (scan speed and layer thickness) on the obtained density, surface quality and hardness of maraging steel 300 parts is investigated. Moreover, various aging heat treatments (different combinations of duration and maximum temperature) are applied on the SLM parts to achieve high hardness values. The mechanical testing of maraging steel 300 specimens produced by SLM and treated with an appropriate aging treatment is accomplished by impact toughness and tensile tests and compared to the results obtained using conventional production techniques. Additionally, the microstructures of as-built and heat treated parts are investigated.Mechanical Engineerin

High-Speed Curtain Recoating for Stereolithography

The University of Leuven uses a liquid curtain recoating system for resin deposition in stereolithography. This system deposits new liquid layers of photo-polymer by means of a liquid curtain travelling over the build vat. Experiments have been carried out to increase the speed of the liquid curtain while depositing a layer. Speeds up to 1.2 m/s, and accelerations up to 1 g have been tested successfully, meaning that it is possible to coat high-quality layers of 75 µm thickness with this recoating technique. However, the curtain restores too slowly after acceleration. This paper discusses possible reasons and tries to formulate adequate solutions. Possible solutions consist in controlling small pressure differences in the curtain’s neighbourhood. A solution to this problem is necessary, as to make the travelling length of the curtain, and so the machine length acceptable with respect to the dimensions of the build vat.Mechanical Engineerin

Management Repercussions Of The Increased Tax On Americans Working Overseas

The Tax Increase Prevention and Reconciliation Act of 2005 extended expiring tax-reduction provisions, and created new ones.  However, not all of TIPRA’s provisions reduce taxes.  Many Americans working abroad ended up paying higher income taxes, retroactive to the beginning of 2006.  This created new managerial challenges for companies that have hired Americans in overseas positions, companies that have previously attempted to accommodate the additional costs these workers incur, and raises serious tax policy questions

Binding Mechanisms in Selective Laser Sintering and Selective Laser Melting

Layer Manufacturing (LM) technologies like Selective Laser Sintering (SLS) were developed in the late 80’s as techniques for Rapid Prototyping (RP). Today, SLS - as well as its derived technology Selective Laser Melting (SLM) - is used as well for prototyping, tooling and manufacturing purposes. This widening of applications is caused mainly by the possibility to process a large variety of materials, resulting in a broad range of physical and mechanical properties. This paper presents a survey of the various binding mechanisms in SLS and SLM, which are responsible for the broad range of materials and applications. Basic binding mechanisms involve solid state sintering, chemically induced binding, liquid phase sintering, partial melting and full melting. Many subcategories can be distinguished based on the type of structural or binder powder composition: single component powder grains (single material or alloy), composite powder grains, mixtures of different powder grains, distinct binder material (sacrificial or permanent), etc. The paper will explain how these binding mechanisms apply for sintering various types of materials: plastics, metal, ceramics and composites (e.g. glass reinforced polymers, cermets, hardmetals, etc.). It gives a survey of research done at the University of Leuven, Belgium, as well as at other European and non-European organizations.Mechanical Engineerin

Section 409A Deferred Compensation Issues for Domestic and International Businesses

Internal Revenue Code (the “Code”) §409A creates special rules for nonqualified deferred compensation plans, including discounted stock options, severance arrangement, and even some expense reimbursement arrangements.  The primary themes of Section 409A are restrictions that it places upon operation of the deferred compensation plan.  In general, it places restrictions on the elections necessary to defer compensation, restrictions on the funding of the plan, and restrictions on the distributions from the plan.   If the requirements of Code §409A and its regulations are not met, all amounts that had been excluded from gross income under the deferred compensation plan are currently included in gross income.  Additionally. there is interest due from the original deferral that is one percentage point higher than the regular rate of interest for underpayments, plus a crushing additional 20 percent penalty.[1] Accordingly it is of paramount importance to understand how these rules apply, and how to avoid the severe penalties. [1] Code §409A(a)