《AA-T17.pdf》由会员分享,可在线阅读,更多相关《AA-T17.pdf(14页珍藏版)》请在三一文库上搜索。
1、COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services _ - I - - - . . . AA TL7 m Ob04500 0009478 L4b m - _ - - - Key Characteristics of- Aluminum Aluminum offers a wide ran
2、ge of properties that can be engineered precisely to the demands of specific automotive applications through the choice of alloy, temper and fabrication process. To name only a few of its advantages, aluminum offers: Strength - Some aluminum alloys and tempers approach or surpass the strength of ste
3、el. The ultimate tensile strength of carbon steel is about 60 ksi. Alumi- num, to cite a few examples, achieves tensile strengths of 45 ksi for alloy 6061-T6; 49 ksi for 2036-T4; 52 ksi for 7016-T5; and 62 ksi for alloy 7029-T6. Alloy 7178-T6 has a tensile strength of 88 ksi; some alumi- num alloys
4、can be heat-treated to strengths approach- ing 100 ksi. Light weight - Aluminum weighs about 35 percent as much as steel by volume: 170 pounds per cubic foot of aluminum, versus 490 pounds per cubic foot of steel. Aluminum auto parts save weight directly and also indirectly through redesign of other
5、 parts. High strength-to-weight ratio - Aluminums strength-to-weight ratio is much higher than that of steel: often double, or more. This property of alumi- num has been a key factor in development of the aero- space industry, and it offers the same advantages to auto designers seeking high performa
6、nce and fuel efficiency. Resilience - Aluminum can deflect under impact and spring back, providing flexible strength and shape retention. But aluminum alloys can also be formulated and treated to maximize stiffness. Corrosion resistance - Aluminum does not rust away on exposure to the environment li
7、ke steel; its natural oxide coating blocks further oxidation. The chance of galvanic corrosion can be minimized by appropriate choices of alloy and design. Forming and fabricating - Aluminum can be formed and fabricated by all common metalworking methods including casting, stamping, forging, bending
8、, extrud- ing, cutting, drilling, punching, machining and finish- ing - often more easily than steel. Joining - Aluminum can be joined by all common methods including welding, soldering, brazing, bolts, rivets, clips, adhesives, clinching, and slide-on, snap- together or interlocking joints. Crashwo
9、rthiness - Aluminum absorbs crash energy more effectively than steel or plastic, providing more protection to auto passengers; it is non-combustible and it does not strike sparks. Cold-resistance - At low temperatures, aluminum does not embrittle; it gains strength, and is often used for cryogenic a
10、pplications. Recyclability - Aluminum has substantial scrap value and a well established market for recycling, provid- ing both economic and environmental benefits. Thermal conductivity - Aluminum conducts heat, transferring it by direct physical contact, about 1.8 times better than copper, pound fo
11、r pound. This makes aluminum an excellent heat exchanger material in both heating and cooling applications. Aluminum heat exchangers are widely used in automotive radiators, air conditioning systems and similar equipment. Aluminums heat-exchanging efficiency also provides advantages for intake manif
12、olds and other engine parts. Reflectivity - Smooth aluminum is highly reflective of the electro-magnetic spectrum, from radio waves through visible light and on into the infrared and ther- mal range. It bounces away about 80 percent of the visible light and 90 percent of the radiant heat striking it
13、s surface. The high reflectivity gives aluminum a decorative appearance; it also makes aluminum a very effective barrier against thermal radiation. suitable for use in automotive heat shields. COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services COPYRIGHT The Al
14、uminum Association, Incorporated Licensed by Information Handling Services AA TL7 m Ob04500 0009479 082 m Aiuminum: The Corrosion Resigtant Automotive Material Contents Introduction. . 2 Designing for Durability . 3 Anticorrosion Design Tips . 4 Aiuminum Parts in the Cars of Today. 7 Aluminum in Aut
15、omobiles-A Brief History . . . . . . . . . . . . . . . 10 References . 12 Use of the information Any data and suggestions contained in this publication were compiled andlor developed by The Aluminum Association, Inc. In view of the vaariery o f conditions and methods o f use to which such data and s
16、uggestions may be applied, the Aluminum Association and its COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services r A A TL7 W O604500 0009480 AT4 W -tntroduction - _- - Aut
17、omotive aluminum use has been growing for years in sunlight. For its new delivery vans, the U.S. Postai (from an average 87 pounds per car in 1976 to 145 pounds in 1987), mainly to cut weight and raise fuel economy. Each pound of aluminum used can reduce vehicle weight as much as 2.25 pounds. Auto f
18、rames and bodies can make further use of aluminums unique combination of strength, light weight, crash- energy absorption, and resistance to heat, cold, and environmental corrosion. As new car prices increase (they doubled between 1978 and 1983), durability and corrosion resistance take on new impor
19、tance. Buyers want vehicles that will retain their appearance and keep a high resale value. And thats something aluminum can provide, as auto makers offer longer warranties against component failure and body rust-out. Unlike steel, aluminum - even unpainted and uncoated - resists conosion by water a
20、nd road salt: its use can avoid the substantial extra costs of galvaniz- ing. coating and painting steel. And aluminum doesnt mst if paint is scratched or chipped. Nor is it weakened or embrittled, as some plastics may be, by desert heat, northern cold, or the ultraviolet radiation Service specified
21、 aluminum bodies designed to last 24 years! . Finally, when a car must be scrapped aluminum is readily recycled, providing both economic and envi- ronmental benefits. Aluminum, with its wide choice of alloys and tempers, offers high quality and a wealth of advantages to automotive engineers developi
22、ng the creative new car designs of the future. 2 COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services AA T17 Ob04500 00094BL 730 m .- Designing for - DuramCRy Uncoated alu
23、minum In normal environmental exposure aluminum does not rust away as steel does. An aluminum surface oxidizes on exposure to air, but this differs from the oxidation of steel in two important ways: Unlike oxidation of steel, aluminum oxide is tran- sparent and invisible to the unaided eye. It does
24、not develop red rust on the aluminum or anything in contact with it. . Unlike steel rust, aluminum oxide clings tightly to the surface of aluminum. It does not flake off, expos- ing fresh surfaces to further oxidation; instead, it forms a protective film that blocks progressive deterioration. With t
25、his natural corrosion resistance, the aluminum bodies of many commercial motor vehicles, rail cars and aircraft are unpainted; aluminum has proven dura- bility in such applications. Coatings Although it performs well without them, aluminum is an excellent substrate for paints and other coatings, oft
26、en applied for esthetic reasons, and sometimes for additional corrosion protection. Adhesion can be maxi- mized by appropriate pre-treatments or undercoats. Anticorrosion en hancement crevices, and designs that shield them from splash greatly.reduce the risk of corrosion. Surface accumulations (“pou
27、ltices”) which retain moisture promote corrosion in much the same way as crevices. Metal surfaces should be designed to shed dirt and liquids; permanent contact between metal surfaces and absorptive materials should be avoided. If these measures are insufficient or impossible, the metal may be given
28、 a protective coating. When dissimilar metals are held in contact in the presence of moisture, galvanic corrosion is possible. Aluminum is anodic to steel and most other common metals, except zinc and magnesium, and so is vulnerable to this type of corrosion. Protection is afforded by keeping bimeta
29、llic junctions dry, and by separating dissimilar metals with coatings or other in- sulators. Anodizing also combats galvanic corrosion by thickening the protective aluminum oxide film. In automotive applications, appropriate designs and precautions can protect aluminum against the most likely enemie
30、s: crevice, poultice, and galvanic corrosion. Unprotected crevices at mating surfaces may collect and retain moisture which may form a pathway for cor- rosive electric currents. Measures that eliminate or seal 3 COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Servic
31、es COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services A A TL7 W Ob04500 0009482 677 W -Anticorrosion DesigniTips Preferred Design Features for Joints and Faying Surfaces Butt Welded Joint h Anodic Metal Cathodic Weld Metal To minimize cornsion attack in butt w
32、elded and lap joints, the weld material (or rivet or bolt) should be less active than the larger area metals being joined. Spot Welded In lap joints, use of fillet welds, insulating material, or a seam sealer is recommended. Insulating Washer or Gasket Insulating Bushing Metallic fasteners which joi
33、n aluminum to a dissimilar metai should be made of an alloy cathodic to alumi- num. For example, use steel bolts in an aluminum-steel joint, not aluminum bolts; aluminized steel bolts a r e even better. Entrapment sites in offset lap welds and standing seams should be eliminated with a d e r or a be
34、ad weld. 4 - Avoid Coating Anode Cathode Coatings should be applied to both anode and cathode or to cathode only, never to the anode only. Damage to coating on anode would result in serious corrosion due to small anode-large cathode combination. Protection can be increased by coating the faying surf
35、aces of the dissimiiar metals as well. Seaiants should be applied to crevices for best results. m I - -2 Avoid Preferred Joints exposed to direct splash should be protected by flanges. These may have to be angled to protect without creating entrapment sites. Avoiding Entrapment Areas Floor Panel Sid
36、e Panel Preferred Avoid Orientation of floor panel and side panel lap joints is angle sections should have rounded comers, smooth 4pers, and drain holes as indicated. /Aluminum Panel 1 Protective Steel Coated or stainless - When joining dissimilar metais design for a large anodd cathode ratio, and i
37、nsulate the entire contact area with a protective coating as shown above. If possible, the steel plate should be galvanized or painted and sealants should be applied to joints. Steel rivets are better than aluminum in such a joint; coated steel or stainless steel rivets are preferred. _ I ,Inner Pan
38、el, Drain Holes Outer Panel Door Deck Lid Drain openings should be properly located to enhance drainage and to prevent entry of road contaminants. Sealant in joint crevices enhances comsion resistance. 40uvered Hole L.- Seal With Plastic Plug When box sections must be used, profide sufficient openin
39、gs for the application and the drainage of protec- tive coatings. Drain flutes and louvred holes should point down and to the rear of the vehicle. Crevices should be painted or sealed. Open t 1 BOX Use open constniction where possible. In a severe corro- sion environment, box sections and enclosed a
40、reas should be avoided or treated with a protective coating. 6 COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services COPYRIGHT The Aluminum Association, Incorporated Licensed by Information Handling Services A A TL7 = 0604500 O009485 386 Versatile, Tough, Durable
41、.;. Alum%-m Parts in the Cars of Today Since the mid-l970s, the percentage of aluminum use in automobiles has more than doubied. Today, more than a hundred types of auto parts are made of engineered alloy aluminum and the list is still growing. While lighter weight and efficient function were the pr
42、imary reasons for selecting aluminum, extended life through better corrosion resistance provided an added benefit that is highly important in achieving the auto industrys rising durability and quality standards. A sampling of those wide-ranging appIications is depicted on these pages. Radiators - Th
43、roughout automobile history, aluminum haSbeen used in the radiators of selected cars. Now, with new production techniques, auto makers are equipping most models with aluminum radiators to take advantage of their light weight, heat- transfer capacity, and corrosion resistance. Aluminum is formable, m
44、achinable, and can be brazed, soldered or welded. Air Conditioners - Aluminum is an excellent conduc- tor of heat and is wideIy used in automotive air con- ditioner condensors, evaporators, liquid lines, and compressor housings. Transmission Housings I - Brake Drums Intake Manifolds Air Conditioners
45、 Engine Heads, Blocks Fuel Injection Systems Brackets , Pi Ri Ht Brake Cylinders bare aluminum provides an attrac- tive, durable natural finish. Aluminum wheels were in- 8 - now have become standard equipment on many makes and models. Pistons - These moving parts must last for the lifc of - - the ve
46、hicle in a demanding environment of high heat, stress. and potentially corrosive compounds. Alumi- num meets these demands. with the added advantage that its light weight makes engines more responsive and efficient in converting fuel energy into vehicle per- formance. Aluminum has been the standard
47、material for automobile pistons since the 1950s. Engine Heads and Blocks - The engine is one of the heaviest single units in an automobile and offers one of the greatest opportunities for weight saving through the use of aluminum. Many cars have aluminum heads and some have aluminum engine blocks as
48、 well. Intake Manifolds - Aluminum allows the production of intake manifolds in more advanced shapes and with thinner walls than are practical in iron. In addition. aluminum engine parts of all kinds present an attrac- tive ”high-tech” appearance under the hood which effectively conveys a sense of t
49、he vehicles quality to potential purchasers. As a result of all these factors, aluminum has become the material of choice for these parts. Fuel Injection Systems - Aluminum offers weight savings. corrosion resistance. machinability and ex- trudability. as manufacturers continue to make fuel in- jection systems smaller and lighter. Aluminum is used for pump housings. tubing and cylinder parts. Driveshafts - This relatively new application of alu- minum was prompted by the metals combination of high strength. light weight. and corrosion resistance in
链接地址:https://www.31doc.com/p-3728155.html