IRONING DIES 4g handbook vukotaboljanovicsheetmetalformingprocesses

Tool and Die Materials Table 13.5 Mechanical properties of quenched and tempered carbon and alloy steels. 179 1040 1060 1080 4340 6150 1875 1469 965 1931 1434 945 Tempering temperature 1675 10 520 1365855 10 430 19 280 1689 8 538 1331 10 420 84 1 17 282 205 425 625 205 425 650 205 425 650 205 425 650 205 425 650 779 758 634 593 552 434 1076 800 524 23 229 1310 1289 889 979 95 1 600 12 13 21 388 375 255 Table 13.5 gives typical mechanical properties of selected carbon and alloy steels in quenched and tempered condition. Applications of Carbon and Alloy Steels Characteristic and typical applications of various carbon and alloy steels are given in Table 13.6.

13.3 TOOL AND DIE STEELS

Tool and die steels are specially alloyed steels that are designed for high strength, impact toughness, and wear resistance. They are commonly used in the forming and machining of metals at both room and ele- vated temperatures. The steel for most types of tool and dies must be in a heat-treated state, generally hardened and tem- pered, to provide the properties needed for the particular application. Thus, tool and die steels must be able to withstand heat treatment with a minimum of harmful effects, dependably resulting in the intended ben- eficial changes in material properties.

13.3.1 Designation and Classification of Tool and Die Steels

The designation and classification system established by and SAE for tool and die steels has seven basic categories. These categories are associated with the predominant application characteristics of the 180 Tool and Die Materials Table 13.6 Typical applications and characteristics of various carbon and alloy steels. Condition TYPE 1117 1020 1030 4320 8620 93 IO Low-carbon Carburizing Grades Soft Carburized HB Medium-carbon Direct Hardening Hot work Cold work High-carbon Direct hardening to H19 Chromium base H20 to H39 Tungsten base H40 to H59 Molybdenum base D High carbon, high chromium A Medium alloy, air hardening 52100 1080 1095 Mold steels Mold steels Water hardening PI to P19 Low carbon P20 to P39 Others L Low alloy F Carbon tungsten W Hardened and tempered Typical applications Poor abrasion resistance and metal-to-metal wear resistance do not hold a cutting edge or sustain high loads. They provide satisfactory service life as pins, guides, shafts, etc. Excellent metal-to-metal wear resistance. Suitable for guide posts and guide rails Same as low carbon. Widely used for parts requiring good strength and toughness: The low stress abrasion and metal-to-metal wear resistance are better than with soft low- and medium -carbon steels. 1080 strip at 450 HB can be used for Rule dies. 52100 at 655 - 680 HB is standard steel for rolling elements. It also has suitable wear properties for short-run dies. 1080 and 1095 steels in strip are widely used for flat springs. tool and die steel types they comprise. A few of these categories are composed of several groups to dis- tinguish between families of steel types that, while serving the same general purpose, differ with regard to one or more dominant characteristics. In Table 13.7 are given the basic types of tool and die steels. Table 13.7 Basic types of tool and die steels. TYPE I BASE CATEGORIES High speed Molybdenum base Tungsten base Tool and Die Materials 181 D7 0 1 0 2 0 6

13.3.2 Cold Work Tool and Die Steels

Cold work steels A, D, and 0 steels are used for cold working operations as well as for sheet-metal form- ing operations, and they are described in more detail in this section. They generally have high resistance to wear and cracking. These steels are available as oil-hardening or air-hardening types. Major alloying elements. Typical analysis results of alloying elements for these types of steels are given in Table 13.8. 2.35 0.40 12.50 1 .oo 4.00 0.40 0.90 1.25 0.50 0.2s 0.2s 0.50 0.90 1.60 0.25 0.30 0.20 0.2s 1.4s 0.2s 0.50 0.25 0.2s 1 Table 13.8 Typical alloying elements for cold work tool and die steels. Machinability Rating Approximate Hardness Characteristics and applications. Machinability and typical applications of common die steels are given in Table 13.9. Table 13.9 Typical applications of common tool and die steels. A2 A6 A8 A9 A2 57 to 62 57 to 60 70 56 to 59 65 to Characteristics and Applications Good combination of wear resistance and toughness, good size stability in heat treatment, good hardenability . Typical applications involve blanking and forming dies, punches, and forming rolls. Air hardening from low temperature, excellent size stability in heat treatment, deep hardening. Typical applications involve blanking and forming dies, punches, coining and bending dies and plastics molds. Optimum combinations of wear resistance and toughness, superior size stability, suitable for highly abrasive hot work requirements. Applications include shear blades, trim dies, forging dies, and plastics molds. Medium resistance to decarburization and to wear. Solid cold heading dies, die inserts, coining des, forming dies, punches, and rolls. 182 Tool and Die Materials Table 13.9 continued D2 D3 D5 0 1 0 2 0 6 50 35 50 90 fairly 125 57 to 62 57 to 64 59 to 63 59 to 61 57 to 61 45 to 63 Very high wear resistance. Excellent size stability, deep hardening in air. Typical applications include dies, drawing dies, shear blades, forming rolls, and trim dies. Excellent abrasion resistance, very high compressive strength, high hardening response. Typical applications include blanking dies, drawing dies, shear blades, forming rolls, punches, and cold trimming dies Very high wear resistance, optimum size stability, and superior resistance to tempering. Applications include blanking dies, shear blades, forming rolls, hot and cold punches, swaging dies, and cold trimming dies. Moderate wear resistance, relatively safe to harden, easy to machine. Common applications include blanking and forming dies, bending and drawing dies, plastics molds, and shear blades. Fairly good wear resistance, relatively safe to harden, fairly easy to machine. General-purpose tooling with a combination of wear resistance and moderate toughness. Excellent machinability, outstanding resistance to wear and galling, easy hardening. Typical applications are gages, punches, cold forming, blanking, and trimming dies, bushings, and other machine tool parts. 13.4 NONFERROUS METALS Many nonferrous metals are used in tool and die, jig, and fixture design. Such materials include alloys of aluminum, magnesium, brass, bronze, zinc-base alloys, and beryllium. Although more expensive than fer- rous metals, nonferrous metals and alloys have important applications because of their numerous positive characteristics, such as low density, corrosion resistance, ease of fabrication, and color choices. Aluminum alloys. The most important factors in selecting aluminum alloys for use in tool and die design are their high strength-to-weight ratio, ease of machinability, resistance to corrosion by many chem- icals, and nonmagnetic properties. Aluminum alloys of series 2024 and 7075 are two of the more widely used alloys for temporary dies, limited production runs, fixture bodies, or other special purposes. Copper alloys. Copper alloys are often attractive for applications where a combination of desirable properties, such as strength, corrosion resistance, thermal conductivity, wear resistance, and lack of