ASTM A681:2008 A4 Steel: Specifications & Listings

ASTM A681:2008 A4: A4: air-hardening cold work tool steel (UNS T30104). Specified in A681:2008.

Category: Tool & Die Steels
Grade Details
GradeASTM A681:2008 A4
Standard ASTM A681:2008
ApplicationsTools, dies and fixtures (clause 1.2)
Grade ComparisonCompare With a Specific Grade →
Grade Standard Match
ASTM A681 A5 ASTM A681:2008 Close Alternative
ASTM A681 P20 ASTM A681:2008 Related Material
EN 10083-3 42CrMo4 EN 10083-3:2006 Related Material
SAE J404 4140 SAE J404:2009 Related Material
SAE J404 4130 SAE J404:2009 Related Material
SAE J404 4135 SAE J404:2009 Related Material
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Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C Mn P S Si Cr Mo
0.95-1.05 1.80-2.20 <=0.030 <=0.030 0.10-0.70 0.90-2.20 0.90-1.40
Mechanical Properties
Hardness <=241 HB
Condition Annealed (maximum Brinell hardness)

More data from ASTM A681:2008

From the standard
Maximum hardness in delivery condition 2 conditions
ConditionMaximum hardness (HB)
Annealed241
Cold drawn262
Maximum Brinell hardness (BHN).
Source: A681:2008, Table 2
Heat treatment and response to hardening hardening test conditions
Preheat temperature
1250 deg F (677 deg C)
Austenitizing, salt bath
1550 deg F (843 deg C)
Austenitizing, controlled atmosphere furnace
1575 deg F (857 deg C)
Austenitizing time
5 to 15 min
Quench medium
Air
Tempering temperature
400 deg F (204 deg C)
Minimum hardness after treatment
61 HRC
Austenitizing temperatures are stipulated for the response to hardening test only.
Source: A681:2008, Table 3

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