The 2004 SAE Ferrous Materials Standards Manual provides a comprehensive compilation of the SAE Technical Reports relating to specifications, testing, and defining of Ferrous Materials. These standards, Recommended Practices, and Information Reports have been developed by Carbon and Alloy Steels Committee, Metals Test Procedures Committee, Automotive Iron and Steel Castings Committee, Sheet and Strip Steel Committee, Elevated Temperature Properties of Ferrous Metals Committee who comprise the Metals Technical Executive Committee (MTEC). MTEC also governs the other Standards, Recommended Practices, and Information Reports that have been developed by prior division that are now inactive. As an informational guide and background for the values and procedures in the SAE Technical Report, HS-30 also includes Examples of Related SAE Technical Papers.
The advancements and expanded usage of magnesium by the automotive industry are highlighted in this publication which contains 46 SAE Technical Papers presented by technology experts at SAE events from 2001 -2005. This information will aid in improving processes, developing new applications, and identifying new technologies to further the competitive edge of magnesium as a lightweight, recyclable, and viable metal to meet global automotive needs. An increased awareness of the benefits ands features of this light weight structural material has opened a wide range of applications within the automotive industry. Examples include instrument panel structures, seat frames, center consoles, transmission cases, front-end and radiator support structures, and hybrid magnesium powertrains. The advancement continues toward developing even higher-performing alloys to further the competitive edge of magnesium.
This online course teaches about the microscopic changes that take place in a precipitation strengthened alloy and their effects on the properties of the alloy. The effects of the different heat treating steps (solution treatment, quench, and aging) and heat treating process parameters (solution treatment temperature and time, quench rate, and aging temperature and time) on the alloy microstructure and the effects on alloy strength are discussed. The course is divided into five modules followed by a quiz.
There are a wide variety of wrought aluminum alloys, each developed to provide specific properties. Getting the strength you need in an aluminum alloy requires knowledge of the effects of alloy composition, cold-working, and heat treating on aluminum metallurgy and properties. A good understanding of how aluminum alloys behave and what can be done to modify their properties is critical for being more productive and profitable. The course takes about one hour to complete and consists of one module and a final exam. Also, quizzes and problems give you opportunities to apply the concepts taught.
AFTER outlining the progress of research in the development of the alloy steels, the author says that alloys of steel containing nickel, chromium, and nickel and chromium, are the most important to the automotive industry, which is especially interested in alloys containing up to 5.0 per cent of nickel and up to approximately 1.5 per cent of chromium, with the carbon content ranging from 0.10 to 0.50 per cent. The additions of these amounts do not materially change the nature of the metallographic constituents, but the elements exert their influence on the physical properties largely by altering the rate of the structural changes. In straight carbon-steel, especially of large sections, it is not possible by quenching to retard the austenite transformation sufficiently to produce as good physical properties as are desired.
PROVISION is made, in the piston and rings described by the author, for an adequate flow of heat from all parts of the piston-head to the cylinder-wall by means of adequate cross-section of aluminum alloy in the head and a tongue-and-groove type of piston-ring structure which provides a greater amount of surface than is usual for heat transfer. A labyrinth oil-seal is provided which aids heat transference and prevents leakage past the piston-rings, and the heat transfer is said to be such that the heat does not destroy the oil seal between the piston and the ring. Charts are included that show the effects in reduced temperatures, oil consumption and gas leakage with the construction described. Attention is given also to a skirt construction most suitable to use with the piston-head and rings described.
ALUMINUM and magnesium, being the lightest commercial metals and therefore the most suitable for aircraft construction, are discussed in their pure and alloyed states. Physical properties of the pure metals and their alloys are given and the effects of adding small quantities of alloying elements are shown. Heat-treating as a means of increasing the strength per unit weight of the alloys is discussed at length, together with the effects of natural aging and artificial aging at elevated temperatures and of quenching in hot and in cold water after heat-treating. The several types of corrosion are considered and resistance to corrosion of the metals and their various alloys are discussed. Protection afforded to aluminum alloy by a surface coating of pure aluminum is described, and other methods are mentioned.
A NUMBER of the more important commercial alloys having aluminum as their base are discussed by the author, who points out their main physical characteristics and outlines methods which can be used in their fabrication, indicating in a general way which alloys are best suited to various aircraft-engine requirements. Tables are given showing chemical compositions and physical properties, including a table of physical properties of various casting alloys at elevated temperatures. Special-purpose alloys are commented upon, and also a new aluminum alloy for pistons which is beginning to find commercial application and possesses properties particularly desirable in aircraft engines. Recent developments in magnesium alloys and their application to aircraft-engine design are specified, tables of physical properties are given, and comments are made on the characteristics of the material as compared with aluminum alloys.
AT first believed immune, aluminum alloys have been found extremely susceptible to both surface corrosion and intercrystalline corrosion. The latter goes on under paint that has been applied to imperfectly cleaned surfaces, and shows only as blisters. Because of this, it has become commonplace to break with the fingers the ribs and the trailing edges of duralumin lower wings and tail-surfaces. Contact of duralumin with brass or steel hastens corrosion, and protective paint coverings are dissolved by dope where fabric surfaces meet metal parts. All-duralumin structures are not considered suitable for sea-going aircraft unless all joints and seams are of water-tight construction, not only in hulls but in other members of the structure. Corrosion over the land is much less severe. Few manufacturers seem awake to the importance of corrosion. The fight to avoid it should begin with avoiding seams that are difficult to protect and hollow members that cannot be sealed hermetically.
SEVEN basic copper-tin-lead bearing-bronzes having high copper contents were studied by the application of various mechanical tests, such as Brinell hardness, resistance to impact, resistance to repeated pounding and resistance to wear. The effects of various additions were investigated by preparing test bearings of the same base alloys with additions of zinc, phosphorus, nickel and antimony, taken singly, and applying the same tests to these. The preparation of the test castings and the methods of testing are described in detail. The chemical analyses are given for the 40 different alloys tested; and the results of the various tests on each group of alloys are reported and discussed in detail, with the observations charted and tabulated for convenient reference. A tabulation of the specifications of 54 different bearing bronzes now in use is included in the paper. Dr. Dowdell presented and discussed∗ the paper for the authors.
EITHER steel or cast iron will provide a good braking surface provided the grain structure is laminated pearlite, according to the author. Such a structure can be secured in pressed steel by alloying or by case-hardening, in high-carbon steel rings welded to a stamped back and in centrifugally cast iron by careful control without alloying. Uniformity of analysis is important and control of the rate of cooling is still more important in castings. The graphite content of iron is not considered important as a lubricant. Methods of centrifugal casting and of testing are illustrated; also the form and microstructure of representative brake-drums. Discussers agree as to the microstructure needed and present additional views as to ways of securing that structure and the desirability of capacity for absorbing and dissipating heat. They believe grain size and strength more important than hardness.
METALLURGISTS must supply engineers with data on the physical properties of steels so that the skill of both can be used, particularly for machinery in which light weight is essential. The engineer who has not a metallurgical department at his command cannot be sure of duplicating results claimed by steel makers, and the physical-property data that have been given in the S.A.E. HANDBOOK are based on minimum results, for safety. More complete information as to what actually can be expected is desirable, and a subcommittee has had a large number of tests made on identical samples from several heats of two alloy steels. The results for these two steels have been coordinated in probability curves that were developed with the aid of frequency charts. Some steels are not uniform in their physical properties in large sections. The author presents suggestions for steels that are suitable for large sections, with the strengths that can be expected from them.
INCREASED quality, which is reflected through higher valve-seat hardness and improved microstructure, can be obtained by additions of nickel and chromium to automobile-cylinder iron. Different combinations of these alloys were used, and it was found that a ratio of three parts of nickel to one of chromium gives the greatest improvement in structure in conjunction with maximum hardness. The effect of prolonged heating on three representative plain irons, as well as on three nickel-chromium-alloyed irons of the same base composition, is also shown. A marked difference is revealed in these cases in favor of alloyed irons. A method is given of producing chilled roller wheels by additions of chromium in the ladle instead of using special cupola charges. This is capable of better control and results in a superior product.
ACHIEVEMENTS of the last ten years in increasing the power-weight ratio of aircraft engines are stated and contributing factors are analyzed. Aluminum alloys have replaced cast iron and steel for certain parts, not entirely because of their lower weight but because of a combination of properties which better fit them for the task. Similar considerations must govern the replacement of aluminum-base alloys by those of magnesium. The most promising immediate field for the magnesium alloys is said to lie in applications wherein strength and lightness are the main considerations and high-temperature properties are of secondary importance. Properties of magnesium castings and forgings are compared with those of castings and forgings of the aluminum alloys. Features of design are discussed which should receive special attention when changing a part from aluminum to magnesium. Machining practices for magnesium are covered in some detail.
COMPARATIVELY large rake and clear angles required for best results leave a relatively thin cutting-edge on a cutting tool for aluminum. One difficulty encountered is that tools of such form are not always available or suitable, for various reasons, for instance, small tools of various types are available only with cutting edges suitable for steel and bronze, and the desirable amount of top rake cannot well be provided on circular form-tools. Tool bits of various sorts can be reground to the desired angle. A simple round form of tip that is shown can be utilized in tools for various purposes, including use as inserted teeth in a face-milling cutter. High-speed-steel tools are suitable for most aluminum alloys, but alloys containing a high percentage of silicon can be machined to advantage only by using cemented tungsten-carbide. Machine-tools should be suitable for high speed.
MORE THAN SEVEN YEARS of investigation of the problem of preventing valve-seat erosion under severe operating conditions in motor-truck and motorcoach engines are reviewed briefly. Engineers are said now to be generally agreed that an insert of some non-ferrous material is the only means of obtaining a valve seat that will stand severe service. A theory for the cause of a thin spotty deposit or pick-up on the valve seat that accelerates erosion is advanced, and this deposit is said to be absent on valve seats made of non-ferrous metals. Aluminum bronze gives satisfactory results but is difficult to secure to cast-iron cylinder-blocks because of its greater coefficient of expansion. Several partially successful methods of securing aluminum-bronze rings to cast iron are shown. A method that is applicable to one alloy which has reduced erosion under the most severe operating condition to such an extent that it is almost negligible is described.