Chemical Composition

Element	Composition, %
Carbon	0.35 max
Manganese	0.60 - 1.05
Phosphorus	0.035 max
Sulfur	0.040 max
Silicon	0.10 - 0.35
Copper	0.40 max [Note B]
Nickel	0.40 max [Note B]
Chromium	0.30 max [Note B, C]
Molybdenum	0.12 max [Note B, C]
Vanadium	0.08 max

Notes
A : For each reduction of 0.01 % below the specified carbon maximum (0.35 %), an increase of 0.06 % manganese above the specified maximum (1.05 %) will be permitted up to a maximum of 1.65 %. B : The sum of copper, nickel, chromium, molybdenum and vanadium shall not exceed 1.00 %.
C : The sum of chromium and molybdenum shall not exceed 0.32 %.

Mechanical Properties

Property		Value
Tensile Strength, min, ksi		70.00
Yield Strength, min, ksi [Note A]		36.00
Elongation in 2 inch.	Round Specimen	22.00
	Strip Specimen 5/16" and Over	30.00
	Strip Specimen, Smaller sizes	See next table
Reduction of Area, min, % [Note B]		30.00
Hardness, HWB, max		187

Notes :
A : Determined by either the 0.2 % offset method or the 0.5 % extension-under-load method.
B : For round specimen only.

Heat Treatment

• Heat treatment is not a mandatory requirement of this specification except for the following piping components:
  • Flanges above Class 300,⁷
  • Flanges of special design where the design pressure at the design temperature exceeds the pressure-temperature ratings of Class 300, Group 1.1,
  • Flanges of special design where the design pressure or design temperature are not known,
  • Piping components other than flanges which meet both of the following criteria: (1) over NPS 4 and (2) above Class 300, and
  • Piping components of Special Class8 other than flanges which meet both of the following criteria: (1) over NPS 4 and (2) when the working pressure at the operating temperature exceeds the tabulated values for Special Class 300, Group 1.1.
• Heat treatment, when required by 6.1 shall be annealing, normalizing, or normalizing and tempering or quenching and tempering in accordance with Specification A961/A961M.
  • Quenching shall consist of either (1) fully austenitizing the forgings followed by quenching in a suitable liquid medium or (2) using a multiple stage procedure whereby the forgings are first fully austenitized and rapidly cooled, then reheated to partially reaustenitize, followed by quenching in a suitable liquid medium. All quenched forgings shall be tempered as prescribed in Specification A961/A961M.

Wall Thickness	Elongation in 2 inch, min, %
5/16	30.00
9/32	28.50
1/4	27.00
7/32	25.50
3/16	24.00
5/32	22.50
1/8	21.00
3/32	19.50
1/16	18.00