Carbon and alloy steels: Uses by SAE/AISI numberUsed for sheet metal, strip, wire, and rod.. steels used where higher strength than the lower-carbon grades is required.. Medium-carbon ch
Trang 1Hot-work tool steels
Chromium base types H1
Low-alloy types L6—Nickel-chromium
Trang 2Oil-hardening types O1—Low manganese
Trang 3Low-alloy types L6—Nickel-chromium
†For large tools and tools having intricate sections, preheating at 1050 to 1200
‡Use moderately oxidizing atmosphere in furnace or a suitable neutral salt bath
§Use protective pack from which volatile matter has been removed, carefully balanced neutral salt bath, or atmospherecontrolled furnaces In the latter case, the furnace atmosphere should be in equilibrium with the carbon content of the steel being treated Furnace atmosphere dew point is considered a reliable method for measuring and controlling this equilibrium
Trang 5Hot-work tool steels
Chromium base types H1
Low-alloy types L6—Nickel-chromium
Like-wise, as the alloy content increases, it becomes necessary to cool slowly from the forg- ing temperature W
steels, this slow cooling is imperative in order to prevent cracking and to leave the steel in a semisoft condition Either furnace cooling or burying in an insulating medium, such as lime, mica, or silocel, is satisfactory
‡The length of time the steel is held after being uniformly heated through at the malizing temperature varies from about 15 min for a small section to about 1 h for large sizes Cooling from the normalizing temperature is done in still air
nor-malizing after forging is to refine the grain structure and to produce a uniform struc- ture throughout the forging Normalizing should not be confused with low temperature (about 1200
§The annealing temperature is given as a range, the upper limit of which should beused for large sections and the lower limit for smaller sections The length of time the steel is held after being uniformly heated through at the annealing temperature varies from about 1 h for light sections and small furnace charges of carbon or low alloy steel to about 4 hr for heavy sections and large furnace charges of high alloy steel
Trang 9met-ric equivalents for approximate tensile strength values and to indicate Brinell hardness values that are beyond the recommended range for this test.
†V
Trang 12Carbon and alloy steels: Uses by SAE/AISI number
Used for sheet metal, strip, wire, and rod Excellent drawing ities Low-strength applications Sheet metal structures, body and fender work, deep-drawing parts of sheet steel.
group These are known as the case-hardening or carburizing grades The higher-manganese grades machine well The higher-
carbon types are used for thicker sections where a stronger core is desired Type 1018 is used for a great many applications, may be easily case-hardened, and is readily available Grades 1020 and
1025 are used for low-strength bolts All these steels are readily welded.
steels used where higher strength than the lower-carbon grades is required All these steels are used for forgings Axles and shafts are made from the 1038 to 1045 group Widely used for machined parts, both heat-treated and non-heat-treated Welding is possible with precautions taken during the cooling process.
steel Used for flat stampings, spring wire, cutting tools, flat springs, and many other high-strength applications These steels are usually heat-treated for their particular application and provide excellent wear resistance Not recommended for welding applications.
SAE/AISI 1215. Similar to 12L14 and low-carbon steel used for studs, nuts, and fasteners Can be case-hardened.
SAE/AISI 12L15. Leaded version of 1215 used for machine parts Can be case-hardened.
Trang 13screw-SAE/AISI 1117 Low-carbon, resulfurized, free-cutting steel used
for shafts, gears, pins, nuts, etc Can be carburized.
SAE/AISI 11L17 Leaded version of 1117 used for screw-machine
parts, gears, shafts, pins, etc Can be carburized.
SAE/AISI 1141. Medium-carbon, resulfurized, free-cutting steel used for shafts, nuts, bolts, etc Can be hardened by heat treatment.
SAE/AISI 4140. Medium-carbon chromium-molybdenum alloy steel used for studs, nuts, bolts, gears, wrenches, shafts, etc Can
SAE/AISI 41L45. Leaded version of 4145, free-machining type Can be heat-treated.
SAE/AISI 4620. Low-carbon nickel-molybdenum steel used for gears, cams, pinions, and shafts Excellent carburizing grade.
SAE/AISI 46L20. Leaded version of 4620, free-machining type Can be carburized.
SAE/AISI 8620 Low-carbon nickel-chromium-molybdenum alloy
steel used for gears, cams, shafts, and pinions Excellent ing grade.
carburiz-SAE/AISI 86L20. Leaded version of 8620, free-machining type Can be carburized.
SAE/AISI 4340. Medium-carbon nickel-chromium-molybdenum alloy steel used for gears and shafting Has high hardenability.
SAE/AISI 8642. Similar to 4340 Has high hardenability.
EF 4130. Aircraft-quality alloy steel.
EF 4140. Aircraft-quality alloy steel.
E 4340, EF 4620, EF 8740, and E 9310. All aircraft-quality alloy steels.
Rather than going into a lengthy description of all the istics and heat-treating properties of all the various grades of car- bon and alloy steels, the preceding tables can be used by the engineer or designer to determine strength, ductility, hardness, and heat-treatment temperatures for each SAE/AISI and ASTM steel listed A metallurgist should be consulted prior to making a final design choice about the various steels used in important or critical applications.
Trang 14character-Stainless steels: Uses by AISI number
Note: The stainless steels listed in the preceding tables typically are known by their three-digit SAE numbers, such as 201, 302, 304,
440, etc The last three digits of the listed SAE numbers are the standard industry identification numbers and are used as such in the following usage summary.
Chromium-nickel stainless steels (austenitic)
rate Excellent weldability.
203 EZ. Superior machinability Good corrosion resistance.
stainless steels.
where high strength and resistance to atmospheric corrosion are required.
proper-ties Resistant to many corrosive conditions.
chemical solutions, many organic chemicals, most dyes, nitric acid, and foods.
303 Pb. Leaded version of 303 used for high-volume automatic machining operations.
Excellent resistance to a high number of corrosive conditions and chemicals.
304 L Extra-low-carbon version of 304 Low carbon content
pre-vents carbide precipitation during welding, which can produce cracks
at the weld joints Excellent weldability.
cold-heading operations.
acids.
Improved over 309 and 304 for corrosion resistance.
Resists pitting and most chemicals Used for paper-mill machinery parts and photographic industry parts and containers High- temperature strength.
316 L. Low-carbon version of 316 that is welded more easily without carbide precipitation.
Trang 15317. Higher alloy content than 316, providing more corrosion resistance.
sub-ject to severe corrosion Excellent corrosion resistance to a wide variety of organic and inorganic substances.
347 Stabilized with Cb and Ta for use in the carbide precipitation
range of 800 to 1500°F, with no impairment to corrosion resistance.
Chromium stainless steels (ferritic)
non-critical exterior parts Economical and easily fabricated.
stainless steel Good mechanical properties and heat resistance Resistant to nitric acid, sulfur gases, and many organic chemicals, including foods.
430 F Free-machining version of 430 Similar in properties to 430.
tempera-tures Excellent in sulfuric atmospheres
Chromium stainless steels (martensitic)
Good resistance to water and atmospheric corrosion.
resistance as 403.
heat-treatable Used where corrosion is not severe.
410 S. Same as 410 except lower carbon range for improved weldability.
resistance Can be heat-treated to Rockwell C 25 to C 43.
416 Free-machining version of 410 with corrosion resistance to
food acids, basic salts, water, and most atmospheric corrosion products.
440 A, B, C, and F. Series of high-carbon stainless steels All are the same basic composition except carbon content Can be heat-treated for high strength and high hardness These steels are corrosion resistant only in the hardened conditions 440 F is a free- machining type used in many applications.
Low-chromium stainless steels
PH13-8Mo
15-5PH
PH15-7Mo
Trang 16physical properties and heat-treating procedures Also see Chap 8.
Typical HSLA steels, with data indicating their mechanical ties, are shown in Table 4.23 Although these are low-alloy grades of steel, they have excellent tensile strength and other properties, making them valuable in many applications HSLA steels were developed more than 75 years ago by Krupp in Germany Some of the older German ordnance steels could be classified as modern HSLA steels, and they also were copper-bearing to improve their resistance
proper-to atmospheric corrosion The famous Mauser M1898 rifles produced for various South American countries had bare polished-metal receivers and bolts.
Many of the HSLA steels rely on carbon, manganese, and silicon contents to achieve the strengths associated with these special materials Other alloying elements such as nickel, chromium, and copper are also present in some of these steels.
Structural steels with very high tensile strengths are referred to
as ultra-high-strength steels An arbitrary minimum yield strength level of 200 ksi has been established for these grades of steels (Some ultra-high-strength steels fall below this arbitrary mini- mum.) Tables 4.24 through 4.30 give the mechanical properties of
(Text continued on page 164.)
Trang 26some ultra-high-strength steels Many of these are considered high-quality specialty steels, with 4340 being used as the refer- ence by which all other types of ultra-high-strength steels are mea- sured AISI type 4340 is used in critical applications, such as key components for aerospace vehicles and commercial and military aircraft.
Aluminum and its alloys are among the most used metallic als, with countless applications and an extremely broad range of physical and chemical properties Pure aluminum is a silvery white metal, light in weight, nontoxic, and easily cast, forged, and machined The pure metal was first isolated in the laboratory in
materi-1827 The method of extracting the metal by electrolysis of mina dissolved in cryolite was discovered by Hall in 1886 in the United States This method is still in use today and is known as
alu-the Hall process Aluminum in its natural forms is alu-the third most
abundant material in the earth’s crust, exceeded only by oxygen and silicon.
Aluminum alloys are mandatory in many design applications of modern technologies Many of the modern aluminum alloys are stronger than some steels on a volume basis and weigh only 34 percent (or one-third) as much as steel The average density of alu-
electrical conductivity of aluminum is 60 percent that of an equal cross-sectional area of copper, which is the second best conductor
of electric current In order of electrical conductivity, the best four elements are silver, copper, gold, and aluminum, respectively.
Tables 4.31 through 4.38 show the physical properties of all the present aluminum alloys Also included are the typical uses for all the wrought and cast types of aluminum alloys in use today Figure 4.2 shows part of the SAE standard delineating alloy and temper designation systems for aluminum.
Copper and copper alloys are also among the most important and most used metallic materials Almost all electrical components and electrical products contain parts made of copper or one or more of its
Trang 27important alloys All the electrical industries worldwide depend
on copper and copper alloys Many new copper alloys have been developed over the past 30 or 40 years, with beryllium-copper alloys
as one of the preferred materials in many electrical applications
as a replacement for the phosphor bronzes The phosphor, silicon, and manganese bronzes have many applications where strength and current-carrying ability, combined with corrosion resistance and nonmagnetic properties, are desired Springs with a high fatigue- endurance limit and good electrical properties are made from the beryllium-copper alloys.
One of the most important uses for copper is in the electrical power distribution industries, where ETP no 110 copper bus con- ductors are used to carry the electrical power for all electrical applications The power distribution industries use such equip- ment as transformers, power stations, power transmission lines, and electrical switch gear and control equipment The electric motor industries are another large user of copper products.
Copper is one of the most important elements, with a specific
conductor of electric current, exceeded only by silver The copper metal is smelted from oxide, sulfide, and carbonate compounds that are found in their natural states as cuprite, malachite, azu- rite, and bornite The most important compounds are the oxides and the sulfates (blue vitriol), the latter being used for agricultural poisons and water purification.
Tables 4.39 through 4.42 list the properties and uses for the many alloys of copper Table 4.43 lists the standard specifications for brass sheet, strip, plate, and rolled bar (ASTM B-36) Table 4.44 lists the standard specifications for phosphor bronze plate, sheet, strip, and rolled bar (ASTM B-103) Tables 4.45 through 4.47 list the standard specifications for beryllium-copper sheet, plate, strip, and rolled bar (ASTM B-194) Table 4.48 presents the ASTM classification of coppers.
Trang 28aThe times and temperatures shown are typical for various forms, sizes, and methods of manufacture
bMaterial should be quenched in water or by high-velocity fans from the solution heat-treating perature as rapidly as possible and with minimum delay after removal from the furnace Unless other- wise indicated, when material is quenched by total immersion in water
Trang 29cThe metal temperature should be attained as rapidly as possible Where a temperature range
dThe time at temperature will depend on the time required for load to reach temperature The times
eThese alloys are supplied in the solution heat-treated condition For optimum properties, subsequent
fMechanical properties of material will meet tensile property limits of T6 temper
gBy suitable control of extrusion temperature, product may be quenched directly from extrusion press
jQuenched at a minimum average cooling rate of 35
k10-min soak at temperature followed by cold water quench
lA minimum of 8 h at room temperature followed by 2 h at 95–105
Trang 31b Only the commonly used tempers are listed for the alloys shown Other tempers of
c The indicated typical mechanical properties for all except the O temper material are higher than the specified minimum properties For O temper products, typical ultimate and yield values are slightly lower than specified (maximum) values.
d Based on 500,000,000 cycles of completely reversed stress using the RR Moore type
e Based on a single series of tests, 10,000,000 cycles sheet flexural specimens.
f Based on 50,000,000 cycles in a single series of tests using the RR Moore type of
g A
h General corrosion ratings are based on exposures to sodium chloride solution by intermittent spraying or immersion Ratings A through D are relative ratings in decreas- ing order of merit The ratings do not necessarily imply acceptable performance in the intended application.
i Stress-corrosion cracking ratings are based on
2XXX, 6XXX, and copper containing 1XXX series alloys and total immersion in boiling in sodium chloride solution for 96 h for copper free 7XXX series alloys.
relative to grain structure; limited failures in laboratory tests of long transverse speci- mens.
j Improved resistance to stress corrosion cracking can be realized by using controlled
k Elongation in 50 mm apply for thicknesses up through 12.50 mm and in 5
l This rating would be B2 for material exposed to elevated temperatures. mThis rating may be different for material held at elevated temperatures for long
p Ratings A through D for workability (cold) and A through E for machinability are
q Ratings A through D for weldability are relative ratings as follows:
Trang 34§The approximate melting range data shown are a practical parameter of the alloy—not concise values Normal and