Alleima® 20C Strip steel

Datasheet updated

2022-07-13 12:32
(supersedes all previous editions)

Alleima® 20C is a hardened and tempered carbon steel characterized by good properties in respect of:

  • Fatigue strength and wear resistance
  • Hardness combined with ductility
  • Dimensional tolerances
  • Surface and edge finishes
  • Shape

The material also has good blanking and forming properties, retaining the shape of the parts after the blanking operation.

Standards

  • ASTM: 1095
  • EN Number: 1.1274

Chemical composition (nominal)

Chemical composition (nominal) %
C Si Mn
1.00 0.25 0.45

Applications

  • Washers in automatic transmissions
  • Lapping carriers and cutter blades for the semiconductor industry
  • Coater and scraper blades for the pulp and paper industry
  • Springs in general
  • Doctor blades for printing processes
  • Knives
  • Trowels

Dimensions

Alleima® 20C is available in a wide range of sizes. The following chart indicates the approximate standard size range.

Figure 1: Standard size range

Finishes and forms of supply

The strip steel can be supplied in coils or lengths with various edges and surfaces.

Blanking and bending

Blanking

In order to achieve optimal blanking results tools and presses must be accurate and stable in dealing with hardened and tempered strip. A lubricant is recommended to minimize tool wear.

Clearance between punch and die

A radial clearance of 4–10% of the strip thickness is recommended. This will give low burr height in combination with long tool life and a sheared edge with a narrow shear zone and a wide break zone.

Tools

Tool steels of type AISI D2 or D4 with hardness about 63 HRC can be used except where thick gauges, slender tool sections and small corner radii are involved. In that case we recommend high-speed steel, type AISI M2 hardened and tempered to about 63 HRC.

Carbide tools are recommended for blanking in very long runs, unless the strip is too hard and thick or the shape of the items is unsuitable. More detailed recommendations will be furnished on request. The corner radii should be min. 0.25 x the strip thickness, but not smaller than 0.25 mm (0.010 in.), and the diameter of the punch not smaller than 2 x the strip thickness.

The risk of the hole slug or the blanked item being carried along with the punch on its return stroke can be lessened by using a die without a taper, i.e. with a straight section starting from the edge of the tool. The straight section should be at least 5 x the strip thickness or at least 3 mm (0.118 in.) in length.

Bending

Table 6 shows average values for the least bending radius, r min . These figures refer to strip with a nominal tensile strength as per table 5. The bending tests were carried out according to Swedish Standard SS 11 26 26 method 3, i.e.in a 90° vee block with a 25 mm (1 in.) die opening, the blanked test pieces being 35 mm (1.38 in.) wide and turned so that their burr edge was facing inwards in the bend.

Mechanical properties

Nominal values at 20°C.

Thickness Tensile strength Proof strength
mm in. MPa psi MPa psi
<0.125 <.005 2100 304 500 1900 276 000
0.125-<0.175 .005-<.007 2050 297 250 1850 268 000
0.175-<0.225 .007-<.009 2000 290 000 1800 261 000
0.225-<0.275 .009-<.011 1950 282 750 1750 254 000
0.275-<0.375 .011-<.015 1900 275 500 1700 247 000
0.375-<0.425 .015-<.017 1850 268 250 1650 239 000
 0.425-<0.475 .017-<.019 1800 261 000 1600 232 000
0.475-<0.625 .019-<.025 1750 253 750 1600 232 000
0.625-<0.825 .025-<.032 1700 246 500 1550 225 000
0.825-<1.000 .032-<.039 1650 239 250 1500 218 000
1.000-<1.575 .039-<.062 1600 232 000 1450 210 000
1.575-<2.500 .062-<.098 1600 232 000 1450 210 000
2.500-<3.500 .098-<.118 1600 232 000 1450 210 000

Physical properties

The physical properties of a steel are related to a number of factors, including alloying elements, heat treatment and manufacturing route, but the data presented below can generally be used for rough calculations.

Density, g/cm3: 7.85
lb/in3: 0.28

Thermal expansion per °C, x10 –6:
from 20°C to 100°C: 10.4
to 200°C: 11.6
to 300°C: 12.4
per °F, x 10 –6 ,
from 68°F to 210°F: 5.8
to 390°F: 6.4
to 570°F: 6.9
Thermal conductivity
at 20°C, W/(m · °C): 49
68°F, Btu/(ft · h · °F): 28

Tolerances

In the standard finish, the tolerances is symmetrical, half above and half below the nominal size. Other tolerances can be discussed. The tolerances are based on the Swedish Standards SS 21 21 10 and 21 21 11 respectively.

Thickness tolerance

The standard tolerance is T1 according to table 3. Closer tolerances can be agreed upon.

Width tolerance

The standard tolerance is B1 according to table 4. Closer tolerances can be agreed upon.

Table 3. Thickness tolerances, T1
Strip thickness Thickness tolerance
mm in. mm± in.±
<0.063 <0.0024 0.005 0.00020
<0.100 <0.0039 0.006 0.00024
<0.125 <0.0049 0.007 0.00028
<0.160 <0.0063 0.009 0.00035
<0.200 <0.0079 0.010 0.00039
<0.250 <0.0098 0.011 0.00043
<0.315 <0.0124 0.013 0.00051
<0.400 <0.0158 0.015 0.00059
<0.500 <0.0197 0.017 0.00067
<0.630 <0.0248 0.020 0.00079
<0.800 <0.0315 0.023 0.00091
<1.000 <0.0394 0.027 0.00106
<1.250 <0.0492 0.034 0.00134
<1.600 <0.0630 0.039 0.00154
<2.000 <0.0787 0.046 0.00181
<2.500 <0.0984 0.050 0.00197
<3.150 <0.1240 0.056 0.00220
<3.500 <0.1380 0.063 0.00248

Table 4. Width tolerances, B1

Thickness Width
mm in. mm in. mm in. mm in. mm in. mm in.
<20 <0.70 <50 <1.97 <125 <4.92 <250 <9.84 <350 <13.8
tolerance
mm± in. ± mm± in.± mm± in.± mm± in.± mm± in.±
<0.25 <0.098 0.07 0.0028 0.10 0.0039 0.15 0.0059 0.20 0.0079 0.30 0.0118
<0.50 <0.020 0.10 0.0039 0.15 0.0059 0.20 0.0079 0.25 0.0098 0.35 0.0138
<1.00 <0.039 0.15 0.0059 0.20 0.0079 0.25 0.0098 0.30 0.0118 0.40 0.0157
<1.60 <0.063 0.20 0.0079 0.25 0.0098 0.30 0.0118 0.35 0.0138 0.45 0.0177
<2.00 <0.079 0.25 0.0098 0.30 0.0118 0.35 0.0138 0.40 0.0157 0.50 0.0197
<2.50 <0.098 0.35 0.0138 0.35 0.0138 0.40 0.0157 0.45 0.0177 0.55 0.0217
<4.00 <0.158 0.40 0.0157 0.45 0.0177 0.50 0.0197 0.60 0.0236

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.