Showing papers on "Forging published in 2008"

High Tensile Ductility and Strength in Bulk Nanostructured Nickel

Abstract: In this Communication, we use cryomillingand subsequently quasi-isostatic (QI) forging processes(formerly known as Ceracon forging), to prepare bulk densemultimodalandbimodalNSNiwithtensileductilityof42%and49%,andyieldstrengthsof457and312MPa,respectively.Thiscombinationofstrengthandductilityismuchsuperiortothoseofthe NS Ni prepared by electro-deposition (ED),

Lean philosophy: implementation in a forging company

Abstract: This research addresses the implementation of lean philosophy in a forging company with a focus on radial forging production flow lines. Here, the prime motive is to evolve and test several strategies to eliminate waste on the shop floor. In this research, a systematic approach is suggested for the implementation of lean principles. This paper describes an application of value stream mapping (VSM). Consequently, the present and future states of value stream maps are constructed to improve the production process by identifying waste and its sources. Furthermore, Taguchi’s method of design of experiments is pursued here to minimize the forging defects produced due to imperfect operating conditions. A noticeable reduction in set-up time and work-in-process (WIP) inventory level is substantiated. Finally, we conclude with a discussion of managerial implications and the future scope of research.

Continuous static recrystallization in ultrafine-grained copper processed by multi-directional forging

Abstract: Annealing processes in copper, processed by multi-directional forging to strains of ɛ = 0.4–6.0 at 300 K, were studied at 503–573 K. Strain-induced ultrafine-grained copper shows mainly grain coarsening behaviour, which is categorized in three stages, i.e. (1) an incubation period, (2) a rapid and limited grain growth and finally (3) a classical (normal) grain growth. That is, in situ or continuous static recrystallization (cSRX) takes place in stages 1 and 2. The annealing characteristics and the mechanisms of cSRX are discussed with reference to those of conventional discontinuous SRX (dSRX).

Cutting forces and surface roughness in hard turning of hot work steel X38CrMoV5-1 using mixed ceramic

Abstract: The aim of this work is to evaluate cutting forces and surface roughness in hard turning of hot work steel X38CrMoV5-1 [AISI H11].This steel is hardened to 50 HRC, machined by a mixed ceramic tool (insert CC650 of chemical composition 70%Al2O3+30%TiC), free from tungsten on Cr-Mo-V ba-sis, insensitive to temperature changes and having a high wear resistance. It is employed for the manufacture of highly stressed diecasting moulds and inserts with high tool life expectancy, plastic moulds subject to high stress and forging dies.The tests of slide-lathing were carried out accord-ing to the method of planning experiments. The results made it possible to study the influence of cutting variables (feed rate, cutting speed and depth of cut) and flank wear (VB) on cutting forces and surface roughness. Mathemati-cal models were established to express the influence de-gree of each cutting regime element on the studied techno-logical parameters. Thus, the ranges of the best cutting conditions adapted, were given.This study confirms that in dry hard turning of this steel and for all cutting conditions tested, the major force is the thrust force and the found roughness criteria are close to those obtained in grinding.

Mechanical Properties of Magnesium Alloy AZ31 after Severe Plastic Deformation

Abstract: Grain refinement of magnesium alloy AZ31 was studied in multidirectional forging (MDF) under decreasing temperature conditions. MDF was carried out up to large cumulative strains of 5.6 with changing the loading direction during decrease in temperature from pass to pass. MDF can accelerate the uniform development of very fine- grained structures and an increase of the plastic workability at low temperatures. New grain structures with the minimal grain size of 0.23 μm can be developed by continuous dynamic recrystallization at a final processing temperature of 403 K. As a result, the multidirectional- forged alloy showed excellent higher strength as well as moderate ductility at room temperature, and also a superplastic elongation of over 300% at 423 K. The mechanisms of strain-induced and fine-grained structure development and of the excellent plastic deformation are discussed in detail.

ESBD technique visualization of material flow in aluminium to steel friction-stir dissimilar welding

Abstract: Friction-stir welding (FSW), considered to be the most significant development in metal joining in a decade, has been the subject of much scientific interest and industrial application. Developed and patented in 1991 at The Welding Institute (TWI) in the UK, the FSW joining process is based on extreme plastic deformation in the solid state and no associated bulk melting is involved. Its application has been guided by a pressing industrial need, successfully applied to the joining of Al alloys, and it appears to be a promising process for joining dissimilar alloys. In recent years, transportation systems have increasingly used light-weight materials, such as high strength steels, Al alloys and Mg alloys, to save energy and reduce pollution. The need to combine such different materials into a hybrid material system, e.g. car bodies and aircraft, is the force driving the development and improvement of welding techniques including FSW. Different concepts for tool materials have lead to increasing interest in FSW of steels as well as of steel-based dissimilar welds. Compared to fusion welding techniques, solid-state welding processes such as FSW have particular advantages for joining dissimilar materials with very different melting intervals and large differences in physical and mechanical properties. It has been shown that mild steels, stainless steels and high strength steels can be friction-stir welded to Al alloys and that the comparatively low heat input characteristic of the process reduces or even prevents the formation of brittle intermetallic phases. In FSW, the joint is created by frictional heating and associated stirring or forging action as the tool moves along the joint interface. Hence, tool geometry, welding parameters, joint design and the materials to be welded exert significant effects on the material flow pattern and temperature distribution. An understanding of the mechanical and thermal processes during FSW is needed for optimising process parameters and controlling the microstructure and properties of the joints. In particular, material flow and operating mechanisms during FSW are not fully characterised. These factors are, however, crucial to the optimisation of tool geometry and welding procedure that is necessary to obtain high structural efficiency welds. Thus, an increase in the number of approaches to investigating material flow during FSW has been observed in the literature. Reynolds et al. used a marker insert technique to provide a qualitative characterisation of material flow metallographically. They described FSW as an in-situ extrusion process where the tool shoulder, the pin, the backing plate, and the cold base material form an extrusion die, where the hot material is extruded around both sides of the pin (leading and trailing) into the cavity being vacated by the pin as it moves forward. Complex material movement has also been analysed in dissimilar joints and has been described as chaotic-dynamic, consisting of vortex-like and swirl features by Murr et al. Moreover, computational methods and tomography techniques appear to be helpful techniques for quantifying and visualising material flow. We investigated the material flow characteristics of buttjoints between AA6181-T4 Al alloy and high-strength DP600 steel. The investigations involved analyses by scanning electron microscopy (SEM) combined with electron back-scattered diffraction (EBSD). EBSD is a SEM add-on package that allows local crystallographic analysis of crystalline microstructure. EBSD has been widely used to investigate morphology, grain size distribution and crystallographic orientation (texture) of similar and dissimilar friction stir welds but so far has not been applied to material flow visualisation. EBSD shows great potential for grain characterisation (quantitative size, shape and aspect ratio) and provides important insight into the material flow analysis. Some microstructure features are also presented in order to correlate the microstructure and material movement with the welding process. C O M M U N IC A IO N S

Recent development in orbital forging technology

Abstract: The main subject of the present work is investigation of possibility of extension of classical orbital forging technology to obtain more cost effective forging process. Orbital forging is the process used for forging of shaped parts by applying the incremental forging method. Results of simulation of orbital forging are compared in the present work with the result obtained from a conventional forging process. 3D finite element (FE) simulations are used in the present project to evaluate the capabilities of the orbital forging process and proper die design, and to predict the forging loads the. Selected results of simulations are presented in the paper. These results are the basis for the further comparison and discussion about possible modifications of conventional orbital forging approach.

Plastic forming of the equal-channel angular pressing processed 6061 aluminum alloy

Abstract: Plastic formability of the ECAP processed 6061 Al alloys with ultrafine grains was examined at relatively low forming temperatures in range between 443 and 553 K. The ECAPed 6061 Al alloys after 8 and 12 passes with submicron size grains and high fractions of high angle boundaries exhibited excellent forging and micro-extrusion abilities. High quality surface was another advantageous feature of the ECAP processed samples. Compressive forging on the 8 passes 6061 Al at 523 K, however, resulted in sharp decrease in strength due to dynamic recovery accelerated in the ultra-fined (sub)grained structure. Micro-extrusion on the 12 passes 6061 Al with 2 mm in diameter was successful at 443 and 553 K. Extrusion without losing the high strength gained through using ECAP, however, could be realized only at 443 K, indicating that high strength components could be made out of the ECAPed 6061 Al using plastic working when the processing temperature was chosen to be much lower than the conventional forging temperature of ∼753 K.

Method for rolling and shaping titanium alloy special-shaped ring forging

Abstract: The invention discloses a rolling and shaping method for a titanium alloy heterotypic ring forging in order to obtain the alloy heterotypic ring forgings with excellent tissues and properties as well as realize accurate rolling. The method includes the following steps: alloy bar material is heated, carried out continuous upsetting and deformed by 65 to 70 percent, so as to be made into a solid cake and then is punched again to lead the alloy bar material to be made into a hollow round cake after the aperture dimension of the alloy bar material is 30 to 35 percent of the dimension of the outer diameter thereof; a rectangle ring blank is obtained after the hollow round cake is heated, rolled circularly and deformed by 25 to 30 percent; a rectangle pre-rolling blank is obtained after the rectangle ring blank is heated, rolled circularly and deformed by 25 to 30 percent again; the pre-rolling blank is heated and arranged in a rolling die of a ring rolling machine and becomes a heterotypic ring forging after being rolled and deformed by 40 to 45 percent in a section groove of the die. When in expansion, the broadening speed of the pre-rolling blank along the radial direction is 2mm/s to 15mm/s with a radial rolling force of 40000kg to 220000kg. The method is mainly used for the shaping of the heterotypic ring forging of an aeroengine or a gas turbine. The method can be adopted to obtain the heterotypic ring forging that is arranged in a flow line along the outline of a part.

Wrought magnesium alloys for structural applications

Abstract: Wrought magnesium alloys are of special interest as lightweight structural components as a result of their more homogeneous microstructures and improved mechanical properties compared to cast components. Extrusion as a shaping technology offers the possibility to produce a wide variety of magnesium alloy profiles. In this contribution, the authors describe the role of extrusion parameters such as extrusion rate, ratio and temperature as well as the type of extrusion process on the microstructure of AZ series magnesium alloys and the resulting mechanical properties. The effect of microstructure on the tensile/compression deformation behaviour of the alloys has also been investigated. In a further step, extruded material has been used in die forging experiments. Aspects of alloy development and process optimisation designed to overcome technical and economic limitations and thus establish magnesium alloy profiles for industrial applications will also be discussed.

Effects of lubricant and lubrication parameters on friction during hot steel forging

Abstract: The aim of the present work is to improved comprehension of wear phenomenon during hot steel forging with sprayed lubricants. The study reported in this paper uses a specific friction test, called the Warm Hot Upsetting Sliding Test (WHUST), which reproduces hot forging contact conditions. Wear markers –such as friction force/normal load ratio or sliding distance before the first scratch– are proposed to characterize the contactor wear at microscopic and macroscopic scales. Friction tests are performed on 1100°C heated specimens to characterize the influence of graphite based lubricant film thickness and particle sizes on friction and wear in the flash zone of a nitrided steel die.

The Potential for SPH Modelling of Solid Deformation and Fracture

Abstract: The advantages of using mesh free simulation methods such as SPH are demonstrated for elastic and elastoplastic deformation and for brittle fracture. The accuracy of SPH for deformation problems is demonstrated using a uniaxial test. An industrial example of forging is shown.

Method for producing wind-electricity principal axis with gathering stock full fibre upset forging

Abstract: The invention relates to a method for producing a wind-power mainshaft by local continuous upsetting and all-fibre upset forging The method comprises the following: step one, the heating of steel ingot; step two, forging; step three, first heat processing; step four, rough machining and ultrasonic inspection; step five, quenching and tempering and heat processing; step six, fine machining, wherein, during the step two, the forging comprises that: (1) a first fire, during which, a steel ingot is subject to upset forging at a forging temperature of between 1250 and 900 DEG C; firstly, the bottom of the steel ingot is sawed off, and the steel ingot is subject to capping and upset forging; (2) a second fire, during which, the steel ingot is stretched towards various directions, marked and subject to intermediate billet cogging; after a pole part is molded, scrap on a T end is chopped and removed; after the forging is finished, the steel ingot returns to a heating furnace for being reheated; (3) a third fire, during which, the steel ingot is subject to local continuous upsetting and all-fibre upset forging; (4) a fourth fire, during which, the steel ingot is subject to rolling and leveling; the pole part is stretched; the disc edge of a hub end on the head part of an intermediate billet material after the local continuous upsetting and all-fibre upset forging is subject to rolling operation; after the rolling, the intermediate billet material is inserted into a leaking disc component again; the end face of the disc is pressed and leveled; after the shaping of the disc end is completed, a manipulator clamps the disc and stretches the pole part of the intermediate billet material to a dimension of a forgeable piece; thus, the mainshaft forging is completed The method can improve the fatigue resisting strength of a wind-power mainshaft forging piece

Influence of cooling rate on phase formation in spray-formed H13 tool steel

Abstract: Spray forming is an effective way to process many tool steels into near-net-shape molds, dies, and related tooling. The general approach involves depositing atomized droplets onto a refractory pattern in order to image the pattern's features. The pattern is removed and the die insert is mounted in a standard mold base or holding block. This approach results in significant cost and lead-time savings compared to conventional machining. Spray-formed dies perform well in many industrial forming operations, oftentimes exhibiting extended die life compared to conventional dies of the same material and design. Care must be exercised when spray forming tool steel dies to minimize porosity and control the nature and distribution of phases and residual stresses. Selection of post-deposition heat treatment is important to tailor the die's properties (hardness, strength, impact energy, etc.) for a particular application. This paper examines how the cooling rate during spray processing and heat treatment of H13 tool steel influences phase formation. Porosity and hardness were evaluated over a range of deposit cooling rates and residual stresses were evaluated for a die in the as-deposited condition. Finally, the performance of spray-formed dies during production runs in forging, extrusion, and die casting is described.

Linear friction welding apparatus and method

Abstract: A linear friction welding head apparatus for dual axis forging, the apparatus including three sets of orthogonal actuators for providing X-, Y-, and Z-planes of apparatus movement for providing Y-axis oscillation, a first forge load along a first forge axis, and a second forge load along a second forge axis. A method for dual axis forging for welding including providing a welding head for applying first and second forge loads along X- and Z-forge axes to weld at more than one interface. The forge loads may be applied at right angles to each other and have magnitudes corresponding to weld interface length.