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Race Engine Technology issue 050 : NOVEMBER 2010
FOCUS : ADVANCED METALS
crankshafts can cost over $20 per pound (£16/k) in the very high purity (VIM-VAR) form; over $5000 for a 26” bar of 7” round suitable for a Cup crankshaft, for example. Certain high-end PM alloys can cost over $24 per pound (£30/k). Some titanium alloys cost over $60 per pound. In the nether-worlds where cost is no object (Formula One, Cup, factory Le Mans teams and suchlike) those numbers might not seem important, but at slightly lower levels, they can be daunting.
THE COMMUNICATIONS HUB OF THE RACING POWERTRAIN WORLD 50 issue AUGUST 2010 USA $20, UK £10, EUROPE e15
www.highpowermedia.com 01 RET50
Cover.indd 1 7/10/10 12:24:02 26 26-27
Metals.indd 26-27 • RaceSHop:
Joe GIBBS RacING Ian Bamsey looks at how JGR develops the engine components and the vital lubrication for them, all under one roof
• SpecIaL: 50/50 What have been the key developments since RET was launched and what can we expect by 2016, when RET reaches its century? Our experts analyse Formula One, NASCAR, Le Mans Prototype, Indy Car and energy recovery systems
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A material world
Wayne Ward takes an in-depth look at the fast-moving world of advanced metals, where every ounce counts
explained in the accompanying sidebar. Stress values are given in ksi, meaning thousands of pounds per square inch (300 ksi = 300,000 psi). The correct selection of a material for a particular application is a highly specialised field and usually requires consideration of a wide spectrum of requirements. In a race engine environment, the demands can be extreme, calling for various combinations of high strength and high fatigue resistance at high temperatures, and the minimum weight which will meet the stress and life requirements. The perfectly- designed race engine component would operate at its design level
T
his article presents details on some new materials for race engine components as well as some additional engineering information on some alloys currently in use. The terms used here to define material properties and processing are
until just after the chequered flag of the last race it was designed to run. The engineering challenge in material selection is complicated by the highly statistical nature of strength and fatigue ratings, as well as the practical problems of cost and availability. Simply stated, what is the point of specifying a 400 ksi material if it has limited availability and/or a cost that makes the target product unaffordable? That trade-off provides the motivation to solve component-life problems by modifying the design to suit materials which are available in commercial quantities and/or for reasonable costs. The word ‘reasonable’ is highly ambiguous in the context of costs in the racing world. The 300- M which my company uses for highly-stressed aircraft components costs over $5 per pound (£4/kilo); nearly $1900 for a 10-foot bar of 2-inch round. The exotic nitriding steel (32CrMoV13) used for certain high-end
• IN coNveRSatIoN WItH: cHRIS SMItH
Chris Smith of Elan Motorsport Technologies tells Anne Proffit how he is helping keep the Ford Modular V8 alive in GT2
STEELS In my Focus on Crankshafts (RET-033), I briefly discussed the ultra- high-strength steel known as 300-M (AMS 6419). This alloy has been used in a variety of high-strength applications including crankshafts, con rods, torsion bars and gears. It is interesting because, although this steel has a remarkable combination of properties (strength, fatigue life, impact resistance and ductility), it has fallen out of favour, primarily because in many instances it has been misused. Here is an example. Suppose a company has been making successful con rods from 4340, and it decides to add a higher strength product. It has heard that 300-M is a great material, so it decides to use it for the new con rod. At a hardness of 44-46 HRc, 4340 has good strength (220 UTS / 200 YS) and impact resistance (22 ft-lb CVN). However, at hardness values above 46, the impact resistance of 4340 becomes quite poor, so 44-46 HRc is the typical hardness for 4340 cranks and con rods. Transitioning to 300-M, some designers have
incorrectly reasoned that since 300-M is a modified 4340 (see Table One), the 300-M part should be tempered back to a similar hardness for good impact resistance. The resulting con rod has issues, and 300- M gets a bad rap. The problem is that even though the strength of 300-M at 44-46 HRc is higher than 4340, its notch sensitivity at 46 HRc is very poor (10 ft-lb CVN). In fact, the peak value for 300-M notch sensitivity occurs at a hardness of 53 HRc, where the value (22 ft-lb CVN) is the same as for 4340 at 46 HRc, but the 300-M has far greater strength (289 UTS / 245 YS). At 53HRc, it is a bit more challenging to machine, but not a significant problem. Further, the extra carbon in 300-M allows a 60HRc surface to be produced on 53HRc through-hardened parts by induction hardening and tempering at 300°F, making it useful for some challenging gear and shaft applications. (Boeing uses lots of 300-M at 52-53 HRc in landing gear components.) Recently, I learned about a new high-strength steel product from
Bohler-Edelstahl, which offers potential for improvements in gearing and shafting applications. This steel, known as W-360, is a high- strength chrome-moly-vanadium alloy, having somewhat different chemistry than the exotic chrome-moly-vanadium crankshaft alloy (32-CrMoV-13) I described in RET-033 (see Table One). W-360 achieves post-heat-treat UTS/YS values of 290 / 270 ksi, with a through-hardness of 56HRc, by austenitizing at 1925°F (1050°C), oil- quenching and triple tempering at 1075°F (580°C). The alloy exhibits extremely low distortion after heat treating.
At 290 / 270 ksi UTS/YS, W- 360 exhibits a 50% reduction of area (ROA) during tensile testing. As an aside: careful examination of Figure Two in the sidebar reveals the ‘necking-down’ a tensile specimen undergoes just before failure. The reduction in cross-sectional area provides a quantitative measurement of a material’s ductility. Although W-360 already has 50 points of carbon, it can be successfully carburized, but a non-standard carbon potential is required. The high tempering temperature allows post-heat-treat nitriding and the application of PVD coatings while retaining the high core strength. With this steel, it is possible to produce a component having carburized gear teeth on one end and nitrided splines on the other.
Gears made from W-360
alloy have been application- tested in an extremely-brutal
27 7/10/10 12:32:13
050 contents
• FocuS: aDvaNceD MetaLS Wayne Ward considers what’s hot and what’s not in the world of advanced metals
• MotoRcYcLe Neil Spalding looks at how the current MotoGP engines have evolved since 2003 and asks, what can we expect in top level motorcycle racing by 2016?
• FocuS: FueL puMpS John Coxon reviews the types of fuel pumps commonly used in racing and looks in depth at the complex issues involved with their deployment
• IReD: NHRa top FueL Anne Proffit surveys the Top Fuel drag race engine builders and investigates the issues surrounding today’s 1000 foot race tracks
ISSUE 048 race engine TECHNOLOGY AUGUST 2010
Porsche 911 GT3 R Hybrid • Mario Illien • Camshaft Focus • Gearbox Focus • Engine Installation • British GP 2010 • Le Mans Prototypes 2010
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