Grade: 55

Chemical Requirements

Elements	Grade55[380]
Carbon,max ^A,B:
1⁄2 in. [12.5 mm] and under	0.18
Over 1⁄2 in. to 2 in. [12.5 to 50 mm], incl	0.20
Over 2 in. to 4 in. [50 to 100 mm], incl	0.22
Over 4 to 8 in. [100 to 200 mm], incl	0.24
Over 8 in. [200 mm]	0.26
Manganese^B:
1⁄2 in. [12.5 mm] and under:
Heat analysis	0.60-0.90
Product analysis	0.55-0.98
Over 1⁄2 in. [12.5 mm]:
Heat analysis	0.60-1.20
Product analysis	0.55-1.30
Phosphorus,max^A	0.025
Sulfur, max^A	0.025
Silicon:
Heat analysis	0.15-0.40
Product analysis	0.13-0.45

A Applies to both heat and product analyses.

B For each reduction of 0.01 percentage point below the specified maximum for carbon, an increase of 0.06 percentage point above the specified maximum for manganese is permitted, up to a maximum of 1.50 % by heat analysis and 1.60 % by product analysis.

Tensile Requirements

	Grade55[380]
Tensile strength, ksi [MPa]	55–75 [380–515]
Yield strength, min,^Aksi [MPa]	30 [205]
Elongation in 8 in. [200 mm], min, %^B	23
Elongation in 2 in. [50 mm], min, %^B	27

A Determined by either the 0.2 % offset method or the 0.5 % extension-under-load method.

B See Specification A20/A20M for elongation adjustment.