ASM Metals Handbook - Desk Edition (ASM_ 1998) Episode 11 pot

electric radiation furnaces. The nature of the furnace charge may range from prealloyed ingot of high quality to charges made up exclusively from low-grade scrap. However, even under optimum melting pouring conditions, molten aluminum is susceptible to three types of degradation: • With time at temperature, adsorption of hydrogen results in increased dissolved hydrogen in the melt. • With time at temperature, oxidation of the melt occurs. • Loss of alloying elements Dissolved Hydrogen. Hydrogen is easily adsorbed by molten aluminum. Unfortunately, the solubility of hydrogen in molten aluminum alloys is substantially greater than in solid aluminum (Fig. 1). When the aluminum alloy solidifies, hydrogen is driven out of solution, exaggerating and enlarging shrinkage porosity, with accompanying loss in mechanical properties (Fig. 2). Sources of hydrogen may include wet charges and damp melting tools, but the primary source of hydrogen is ambient humidity. Because little can be done to prevent hydrogen pickup during melting, hydrogen must be removed from the melt before pouring. The most common method used is bubbling dry nitrogen or argon through the melt. Rotary degassing units, as described and illustrated in the article "Melting Methods" in this Section (see Fig. 17 of that article), are particularly effective. These units may be inserted into melting crucibles for use. The use of chlorine gas is especially effective in removing hydrogen; however, environmental and safety considerations generally preclude its use in production. Fig. 1 Solubility of hydrogen in aluminum at 1 atm hydrogen pressure Fig. 2 Ultimate tensile strength versus hydrogen porosity for sand cast bars of three aluminum alloys Measurement of the amount of hydrogen dissolved in the melt has historically been done using a reduced pressure test in which a sample of molten aluminum is poured into a small steel cup and allowed to solidify in a vacuum chamber. Solidification is observed; the degree of evolution of bubbles during solidification indicates the amount of hydrogen present. Subsequent sectioning of the solidified sample and inspection of the size of the pores formed is also used. Unfortunately, these methods are inaccurate and are heavily influenced by the presence in the melt of oxide particles that act as nuclei for the hydrogen bubbles. The preferred way to test for dissolved hydrogen is to use instruments specifically designed to show hydrogen by liquid extraction techniques. Oxidation of the Melt. Aluminum forms a very stable oxide that forms instantaneously on the surface of the melt. The rate of oxidation increases with temperature and the presence of certain alloying elements, such as magnesium and beryllium. While the oxide film that forms on the surface of an aluminum melt is self-limiting if the surface of the melt is not disturbed, any turbulence will mix the oxide film into the bulk of the melt and create a fresh surface for the formation of more oxide. The oxide films and oxide inclusions that result are especially detrimental to the performance of aluminum castings. Turbulence may be induced during alloying operations, molten metal transfer, or pouring and mold filling. Oxide particles in the melt serve as nuclei for the formation of shrinkage and gas porosity. In the absence of oxide inclusions, porosity and microporosity are substantially reduced. This is an especially important consideration in aluminum casting alloys, as they often have very large liquidus-to-solidus spreads and freeze in a mushy manner making feeding very difficult. Oxide films in the casting form planes of weakness that nucleate failure under load. Much of the scatter in mechanical properties of cast aluminum alloys results directly from the presence of these films. When they are absent, the scatter is reduced, and the reproducibility of casting properties surpasses that of forgings. The films are not normally visible during radiographic inspection and must be prevented rather than found and repaired. Oxides are controlled by using covering fluxes during melting. These fluxes are usually magnesium chloride salts, and they float on the melt surface. They must be removed from the surface of the melt periodically. Suspended oxide inclusions are removed from large melters by passing the melt through a filter bed. In smaller operations, the oxides are removed by placing filters in the gating system. Prevention of the formation of oxide films in the casting requires that the metal enter the mold cavity in a non-turbulent manner. As this is not possible using gravity pouring methods for most castings, because the head height of sprues accelerates the metal to speeds where turbulent flow takes place, counter-gravity or liquid-level mold filling techniques must be used. While filters slow the velocity of the metal, they rarely slow it enough to prevent oxidation. Mold cavities must be filled from the bottom, and the sequence in which different levels in the casting fill must be carefully planned to avoid "waterfalling," the dropping of liquid metal from a higher to a lower level in the mold, and the resulting oxidation of newly created metal surface. By filling the mold from the bottom, the oxide layer on the top of the liquid metal will rise to the top of the cope surface and flow into top risers where it will not harm the casting. Loss of Alloying Elements. Many aluminum casting alloys contain elements such as magnesium that react with oxygen over time. If molten metal is held too long, these elements will be lost, and the chemical composition of the resulting casting will not be within specification. Other alloying elements, such as zinc, may have low vapor pressures and evaporate from the surface of the bath. Structure Control Aluminum alloy melts are commonly treated to produce the desired metallurgical microstructure during solidification. Both nucleation of the primary dendrites and the form of the eutectic are controlled. Dendrite Arm Spacing. In all commercial processes, solidification takes place through the formation of dendrites in the liquid solution (see the article "Solidification of Metals and Alloys" in this Section). The cells contained within the dendrite structure correspond to the dimensions separating the arms of primary dendrites and are controlled for a given composition exclusively by solidification rate. Dendrite cell sizes on the order of 25 m produce optimum mechanical properties in aluminum castings. Grain Structure. A fine, equiaxed structure is normally preferred in aluminum alloys, as such a structure improves feeding, the response to heat treatment, and mechanical properties. Grain refinement is accomplished through the addition of small amounts of master alloys (grain refiners) of titanium (containing 3 to 10% Ti) or titanium and boron (containing 0.2 to 1% boron and titanium-to-boron ratios of from 5 to 50). The effect is dramatic, as shown in Fig. 3. Care must be taken in using these grain refiners to avoid excessive superheating of the melt. In addition, because titanium oxidizes easily, the metal must be poured soon after grain refinement treatment, or the titanium will no longer be available to act as a grain refiner. Fig. 3 As-cast Al- 7Si ingots showing the effects of grain refinement. (a) No grain refiner. (b) Grain refined. Both etched using Poulton's etch; both 2× Refinement of Hypoeutectic Alloys. Many sand and permanent mold aluminum-silicon alloys are hypoeutectic and benefit from refinement or "modification" of the silicon eutectic phase. This is done by adding small amounts of sodium, strontium, calcium, or antimony to the melt prior to pouring. These elements reduce the size of the eutectic silicon plates that form, decrease their interlamellar spacing, and change their morphology (Fig. 4). This change in silicon morphology improves casting properties. Silicon, strontium, and calcium are compatible, meaning that they can be mixed, an important consideration when charges may be made up from purchased scrap. Antimony, however, is not compatible with the other modifiers, and must be kept out of melts containing them. Fig. 4 Varying degrees of aluminum- silicon eutectic modification ranging from unmodified (A) to well modified (F) The use of strontium and sodium is usually accompanied by an increase in hydrogen content of the melt. Inert gas degassing treatments must be used in this case. Because the silicon eutectic can also be modified by rapid cooling rates, foundries that pour thin-section castings (that solidify rapidly) often do not add modifiers to their melts. When using modifiers, the phosphorus content of the melt must be kept below 5 ppm in hypoeutectic alloys. Refinement of Hypereutectic Alloys. In hypereutectic aluminum-silicon alloys, phosphorous, in the form of phosphor-copper or phosphorous pentachloride, changes the distribution and morphology of the silicon phase (Fig. 5). In refining hypereutectic melts, the bath temperature should be kept to a minimum, and impurities that react with phosphorous should be removed prior to modification treatment. Phosphorus refinement substantially improves mechanical properties and castability of hypereutectic alloys. Fig. 5 Effect of phosphorus refinement on the microstructure of Al-22Si-1Ni- 1Cu alloy. (a) Unrefined. (b) Phosphorus-refined. (c) Refined and fluxed. All 100× Sand Casting and Permanent Mold Alloys Alloy Compositions. Although a great many aluminum casting alloys have been developed, only a few are used widely. These are the hypoeutectic aluminum-silicon alloys containing small amounts of magnesium and/or copper. Table 1 lists compositions of common aluminum-silicon alloys. Copper is also used in some alloys as the major alloying constituent. The most popular alloy, A356.0, used for most automotive and general purpose castings, contains 6.5 to 7.5% Si and 0.25 to 0.45% Mg. A variation of this alloy, used for aircraft castings, increases the magnesium content to 0.55 to 0.60% while reducing the level of residual elements allowed in the alloy. Table 1 Compositions of common aluminum-silicon alloys Nominal composition (b) , % Alloy Product (a) Cu Mg Mn Si Others 355.0 S, P 1.2 0.50 0.50 max 5.0 0.15Ti A356.0 S, P . . . 0.35 0.35 max 7.0 . . . A357.0 S, P . . . 0.60 0.03 max 7.0 0.15Ti, 0.04Be 360.0 D . . . 0.50 0.35 max 9.5 . . . 380.0 D 3.5 . . . 0.50 max 8.5 . . . 390.0 D 4.5 0.60 0.10 max 17.0 . . . 413.0 D . . . . . . 0.35 max 12.0 . . . B443.0 S, P . . . . . . 0.50 max 5.2 . . . (a) S, sand casting; P, permanent mold casting; D, die casting. (b) All compositions contain balance of aluminum. Eliminating Microporosity. A major problem in the manufacture of aluminum alloy castings is elimination of microporosity. These alloys have large mushy zones (liquidus-to-solidus spreads) and, because of the high heat of fusion of aluminum, tend to solidify more slowly than iron castings. Delivery of feed metal to areas where shrinkage is occurring in the casting is difficult, as the feed metal must wind its way through the growing dendrites. When the mesh of dendrites becomes coherent, which occurs when the casting is less than 50% solid, movement of liquid metal through the dendrite mesh becomes extremely difficult and microporosity results. Pore size is increased by the presence of hydrogen gas coming out of solution, which is why it is important to thoroughly degas the metal before pouring. However, as the shrinkage pores nucleate heterogeneously on inclusions, the number of pores can be significantly reduced by eliminating the presence of oxide inclusions and oxide films in the casting. This is accomplished by avoiding the introduction of oxygen during melting, carefully removing the oxide skin that forms spontaneously on the surface of the melt, using ceramic filters in the mold, and filling the mold using counter-gravity techniques. The most effective way to eliminate porosity in aluminum alloy castings is to decrease the length of the mushy zone through which the feed metal must travel during solidification. This is done by establishing very high thermal gradients in the casting by arranging metal chills and risers in the mold strategically and insulating the risers. Castings made using this practice are often referred to as "premium quality castings." Alloys commonly considered premium by definition and specifications are 201.0, C355.0, A206.0, A356.0, 224.0, A357.0, 249.0, 358.0, and 354.0. Unfortunately, the high heat of fusion of these alloys limits the section size over which it is possible to establish effective thermal gradients. For this reason, few aluminum castings are made in sections heavier than 25 mm (1 in.). Complete elimination of microporosity in aluminum castings is generally not possible, unless the castings are hot isostatically pressed after casting. It should be pointed out that the techniques used to control microporosity generally reduce it to a level where it has little effect on static and dynamic properties. Melt Practice. Degassing, addition of grain refiner and addition of the eutectic modifier are carried out during melting. Avoiding oxide formation is a major concern in melting and pouring. Molten metal transfer from melting furnace to pouring ladle must be done with minimum turbulence. When gravity pouring is used to fill the mold, it is essential to position the pouring ladle as close to the pour cup as possible, in no case more than 25 mm (1 inch) above the cup. Turbulence must be avoided in the flowing stream. As in the casting of ferrous metals, venting the mold is important to assure that the mold fills evenly. Permanent molding is often used to make aluminum alloy castings. In this case the thermal gradients may be established by using the metal mold as the chill and placing resin-bonded sand inserts in the mold to slow solidification in that area. Permanent molding is widely used in the automobile industry. Heat Treatment. Aluminum casting alloys develop their properties as a result of heat treatment. The heat treatments used are generally solution heat treatment, quenching, and aging. The aging treatment employed can be varied to control specific properties to a desired specification. In solution heat treatment, the casting is heated into the single-phase zone on the phase diagram but generally not above the eutectic temperature (Fig. 6). To obtain the maximum advantage from solutionizing treatments, there must be as little segregation in the cast structure as possible, as heavily segregated castings contain pockets of segregated alloying elements that melt at temperatures below the solutionizing temperature. These areas melt during heat treatment but do not re-solidify with the proper structure, thereby substantially decreasing casting properties. Segregation is avoided by using rapid solidification rates and restricting the amount of low-melting point elements in the alloy composition. As most permanent mold and sand castings are solidified at as high a rate as can be obtained to minimize the formation of microporosity, segregation is rarely a problem. Fig. 6 Portion of aluminum- copper binary phase diagram. Temperature ranges for annealing, precipitation heat treating, and solution heat treating are indicated. Castings are held at the solutionizing temperature long enough to dissolve the alloying elements into the matrix. The amount of time required varies with the alloy, section size, and solutionizing temperature; higher temperatures require less time. The time also varies with section thickness; thicker sections take longer to reach the solutionizing temperature. No special atmosphere controls are needed for aluminum heat treatment. However, control of the furnace temperature in all parts of the furnace is essential to avoid overheating and the possibility of melting interdendritic regions where some microsegregation exists. After solution heat treatment, the castings are quenched to retain the alloying element in supersaturated solution. The quenchant used is normally water held near its boiling point. Although better properties are obtained when castings are quenched into room temperature or refrigerated water, quenching often distorts castings, and the degree of distortion increases as the quenchant temperature decreases. Distortion occurs because different parts of the casting cool at different rates, depending on their surface area-to-volume ratio (as in solidification) and, more importantly, on whether or not bubbles of steam form on the surface in the quenching medium, thereby insulating that section of the casting and slowing its cooling rate. Distortion results from the stresses set up as the casting contracts during cooling and when sections of the casting cool at rates different from that of neighboring sections, thus contracting at different rates. The key to minimizing quench distortion is to obtain uniform cooling over all parts of the casting. One quenching method that does this is quenching into a fluidized bed of small refractory particles. After the castings are quenched, they are heated to an intermediate temperature to precipitate the supersaturated phases that strengthen the casting and give it its properties. The properties developed depend on the alloy, the temperature selected, and the time the casting is held at the aging temperature. Castings are air cooled after aging. Aluminum castings may be annealed to remove residual stresses; however, annealing destroys the effects of the aging treatment. Die Casting Alloys Alloy Compositions. Alloys used in sand casting are rarely used in pressure die casting. This is because the steel die material is soluble in molten aluminum. Therefore, iron is added to die casting alloys in amounts above 0.7%, which stops dissolution of the die in the alloy. Low-iron alloys solder to the die, and the castings cannot be removed from the die easily. (The problem is avoided in permanent mold castings by applying a refractory coating to the surface of the mold.) The most commonly used die casting alloys contain 7.5 to 9.5% Si, 1.3 to 2% Fe, 3 to 4% Cu, and 0.5% Mn. Of these, Alloy 380 listed in Table 1 and its variations predominate. Magnesium is not added to die casting alloys because it oxidizes during the shot and forms inclusions in the casting. The addition of iron, unfortunately, lowers casting ductility. In addition, iron reacts with other alloying elements to form insoluble intermetallic compounds in the melt. These intermetallics have the beneficial effect of increasing alloy strength, particularly at higher temperatures. However, these insoluble compounds can build up in melting and holding furnaces and transfer launders, creating a sludge that, if inadvertently included in the metal used for a casting, produces hard and brittle inclusions in the casting. Die casters are familiar with composition limits that prevent sludge formation. A common rule is that iron content plus two times manganese content plus three times chromium content should not exceed the sum of 1.7%. This limit is arbitrary and inexact; it is often assigned values from 1.5 through 1.9%, and it is subject to the specific composition and actual minimum process temperature. Melt practice for die casting alloys differs from that for sand and permanent mold alloys, primarily because the high velocities under which the metal enters the die in this casting process often trap air in the casting. Because of this, properties of die castings are not expected to be as high as those of sand and permanent mold castings. Therefore degassing, grain refinement, and eutectic modification are traditionally not done in preparing die casting melts. However, the development of vertical squeeze casting and slow-fill techniques that eliminate the entrapment of air into the casting are now permitting die casters to make use of melt preparation methods that eliminate gas and inclusions and lead to much higher properties in die castings than those obtainable before. The vertical squeeze casting process is described and illustrated in the article "Molding Methods" in this Section (Fig. 22). Heat Treatment. Because of the entrapped air in conventional die castings, these alloys are not heat treated (the air expands during heating, forming blisters on the surface of the casting). However, as castings made by the vertical squeeze casting method are generally free of entrapped air, they may be heat treated to develop a variety of useful properties. Copper Alloys COPPER is alloyed with other elements because pure copper is extremely difficult to cast and prone to surface cracking, porosity problems, and the formation of internal cavities. The casting characteristics of copper can be improved by the addition of small amounts of elements including beryllium, silicon, nickel, tin, zinc, chromium, and silver. When casting copper alloys, the lowest possible pouring temperature needed to suit the size and form of the solid metal should be adopted to encourage as small a grain size as possible as well as to create a minimum of turbulence of the metal during pouring. Recommended pouring temperatures for copper foundry alloys are listed in Table 2. Table 2 Pouring temperatures of copper alloys Light castings Heavy castings Alloy type UNS No. °C °F °C °F Group I alloys Copper C81100 1230-1290 2250-2350 1150-1230 2100-2250 Chromium copper C81500 1230-1260 2250-2300 1205-1230 2200-2250 C85200 1095-1150 2000-2100 1010-1095 1850-2000 C85400 1065-1150 1950-2100 1010-1065 1850-1950 C85800 1150-1175 1950-2150 1010-1095 1850-2000 Yellow brass C87900 1150-1175 1950-2150 1010-1095 1850-2000 C86200 1150-1175 1950-2150 980-1065 1800-1950 C86300 1150-1175 1950-2150 980-1065 1800-1950 C86400 1040-1120 1900-2050 950-1040 1750-1900 C86500 1040-1120 1900-2050 950-1040 1750-1900 C86700 1040-1095 1900-2000 950-1040 1750-1900 Manganese bronze C86800 1050-1175 1950-2150 980-1065 1800-1950 C95200 1120-1205 2050-2200 1095-1150 2000-2100 C95300 1120-1205 2050-2200 1095-1150 2000-2100 C95400 1150-1230 2100-2250 1095-1175 2000-2150 C95410 1150-1230 2100-2250 1095-1175 2000-2150 Aluminum bronze C95500 1230-1290 2250-2350 1175-1230 2150-2250 C95600 1120-1205 2050-2200 1095-1205 2000-2200 C95700 1065-1150 1950-2100 1010-1205 1850-2200 C95800 1230-1290 2250-2350 1175-1230 2150-2250 C97300 1205-1225 2200-2240 1095-1205 2000-2200 C97600 1260-1425 2300-2600 1205-1315 2250-2400 Nickel bronze C97800 1315-1425 2400-2600 1260-1315 2300-2400 C99700 1040-1095 1900-2000 980-1040 1800-1900 White brass C99750 1040-1095 1900-2000 980-1040 1800-1900 Group II alloys C81400 1175-1220 2150-2225 1220-1260 2225-2300 C82000 1175-1230 2150-2250 1120-1175 2050-2150 C82400 1080-1120 1975-2050 1040-1080 1900-1975 C82500 1065-1120 1950-2050 1010-1065 1850-1950 C82600 1050-1095 1925-2000 1010-1050 1850-1925 Beryllium copper C82800 995-1025 1825-1875 1025-1050 1875-1925 C87500 1040-1095 1900-2000 980-1040 1800-1900 Silicon brass C87800 1040-1095 1900-2000 980-1040 1800-1900 C87300 1095-1175 2000-2150 1010-1095 1850-2000 C87600 1095-1175 2000-2150 1010-1095 1850-2000 Silicon bronze C87610 1095-1175 2000-2150 1010-1095 1850-2000 Copper nickel C96200 1315-1370 2400-2500 1230-1315 2250-2400 [...]... Fe-1.0C Fe-0.50C-1.5Cr-2.5W Fe-0.9C-1Mn-0.5Cr-0.5Mo Fe-1C-5Cr-1Mo Fe-1C-2Mn-1Cr-1Mo Fe-1.5C-12Cr-1Mo-1V Fe-2.25C-12Cr Fe-1.5C-12Cr-1Mo-3Co Fe-2.35C-12Cr-1Mo-4V Fe-0.8C-4Cr-5Mo-6W-2V Fe-1.3C-4Cr-4.5Mo-5.5W-4V Fe-1.5C-8Cr-4V-1.5Mo Fe-2.9C-8Cr-9.8V-1.5Mo Fe-2.45C-5Cr-9.75V-1.3Mo Fe-0.10 to 0.20C Fe-3C-1.6Si-0.7Mn Fe-3C-1.6Si-0.4Cr-0.4Mo Fe-0.75C Fe-0.45C-1.1Cr-0.4Mo Fe-0.4C-0.6Mn-0.3Si-1Cr-0.2Mo Fe-0.4C-1.2Cr-0.2Mo-1Al... 137 0-1 480 250 0-2 700 129 0-1 370 235 0-2 500 C83450 117 5-1 290 215 0-2 350 109 5-1 175 200 0-2 150 C83600 115 0-1 290 210 0-2 350 106 5-1 175 195 0-2 150 C83800 115 0-1 260 210 0-2 300 106 5-1 175 195 0-2 150 C84400 115 0-1 260 210 0-2 300 106 5-1 175 195 0-2 150 C84800 115 0-1 260 210 0-2 300 106 5-1 175 195 0-2 150 C90300 115 0-1 260 210 0-2 300 104 0-1 150 190 0-2 100 C90500 115 0-1 260 210 0-2 300 104 0-1 150 190 0-2 100 C90700 104 0-1 095 190 0-2 000 98 0-1 040... 98 0-1 040 180 0-1 900 C 9110 0 104 0-1 095 190 0-2 000 98 0-1 040 180 0-1 900 C91300 104 0-1 095 190 0-2 000 98 0-1 040 180 0-1 900 C92200 115 0-1 260 210 0-2 300 104 0-1 175 190 0-2 150 C92300 115 0-1 260 210 0-2 300 104 0-1 150 190 0-2 100 C92600 115 0-1 260 210 0-2 300 105 0-1 150 192 0-2 100 C92700 117 5-1 260 215 0-2 300 106 5-1 175 195 0-2 150 C92900 109 5-1 205 200 0-2 200 104 0-1 095 190 0-2 000 C93200 109 5-1 230 200 0-2 250 104 0-1 121 190 0-2 050 C93400 109 5-1 230... 200 0-2 250 104 0-1 121 190 0-2 050 C93400 109 5-1 230 200 0-2 250 101 0-1 150 185 0-2 100 C93500 109 5-1 205 200 0-2 200 104 0-1 150 190 0-2 100 C93700 109 5-1 230 200 0-2 250 101 0-1 150 185 0-2 100 Group III alloys Leaded red brass Leaded semired brass Tin bronze Leaded tin bronze High-leaded tin bronze C93800 109 5-1 230 200 0-2 250 104 0-1 150 190 0-2 100 C94300 109 5-1 205 200 0-2 200 101 0-1 095 185 0-2 000 Types of Copper Alloys Copper alloys... highpressure die casting: magnesium-aluminum-zinc-manganese (AZ), magnesium-aluminum-manganese (AM), and magnesium-aluminum-silicon-manganese (AS) Systems used for sand and permanent mold castings include: magnesium-aluminum-manganese with and without zinc (AM and AZ), magnesium-zirconium (K), magnesium-zinczirconium with and without rare earths (ZK, ZE, and EZ), magnesium-thorium-zirconium with and without... alloys Hot-rolled low-carbon steel Unalloyed cast iron, 185 to 225 HB Alloy cast iron, 200 to 250 HB Cast high-carbon steel, 185 to 225 HB Cast alloy steel, 200 to 235 HB 4140 alloy steel 4140 modified Nonferrous alloys Zinc alloy (UNS Z35543) Aluminum bronze (UNS C62500), 270 to 300 HB Nonmetals Polyester-glass Epoxy-glass Polyester-metal Epoxy-metal Nylon-metal Polyester or epoxy-glass-metal (a)... magnesium-thorium-zirconium with and without zinc (HK, HZ, and ZH), magnesium-silver-zirconium with rare earths or thorium (QE and QH), magnesium-yttrium-rare earth-zirconium (WE), and magnesium-zinc-copper-manganese (ZC) Compositions and properties of these alloys are listed in the Section "Magnesium and Magnesium Alloys" in this Handbook The AZ family of alloys is grain refined by the addition of pellets... sheet metal forming (a) Thick-film lubrication (b) Thin-film lubrication (c) Boundary lubrication Thick-film (hydrodynamic) lubrication (Fig 5a) is the occurrence of a thick film of lubricant between tool and workpiece that completely prevents the metal-to-metal contact Thin-Film (Quasi-Hydrodynamic) Lubrication The film between tool and workpiece is thinner, and some metal- to-metal contact takes place... Fe-1.5C-8Cr-4V-1.5Mo Fe-2.9C-8Cr-9.8V-1.5Mo Fe-2.45C-5Cr-9.75V-1.3Mo Fe-0.10 to 0.20C Fe-3C-1.6Si-0.7Mn Fe-3C-1.6Si-0.4Cr-0.4Mo Fe-0.75C Fe-0.45C-1.1Cr-0.4Mo Fe-0.4C-0.6Mn-0.3Si-1Cr-0.2Mo Fe-0.4C-1.2Cr-0.2Mo-1Al Zn-4Al-3Cu-0.06Mg Cu-13Al-4Fe 50% polyester, 50% glass in the form of cloth, strand, or chopped fibers 50% epoxy, 50% glass as above Polyester reinforced with metal powder Epoxy reinforced with metal powder... Cast Metal-Matrix Composites METAL-MATRIX COMPOSITES (MMCs) offer unique properties that may have advantages in certain applications Both particulate-reinforced MMCs and fiber-reinforced MMCs can be produced by casting methods Additional information on the processing and properties of MMCs can be found in the Section "Special-Purpose Materials" in this Handbook Casting MMCs For particulate-reinforced . 115 0-1 175 195 0-2 150 98 0-1 065 180 0-1 950 C86300 115 0-1 175 195 0-2 150 98 0-1 065 180 0-1 950 C86400 104 0-1 120 190 0-2 050 95 0-1 040 175 0-1 900 C86500 104 0-1 120 190 0-2 050 95 0-1 040. 190 0-2 000 98 0-1 040 180 0-1 900 C92200 115 0-1 260 210 0-2 300 104 0-1 175 190 0-2 150 C92300 115 0-1 260 210 0-2 300 104 0-1 150 190 0-2 100 C92600 115 0-1 260 210 0-2 300 105 0-1 150. 122 0-1 260 222 5-2 300 C82000 117 5-1 230 215 0-2 250 112 0-1 175 205 0-2 150 C82400 108 0-1 120 197 5-2 050 104 0-1 080 190 0-1 975 C82500 106 5-1 120 195 0-2 050 101 0-1 065 185 0-1 950