ASTMA A 350/A 350M: American Society for Testing and Materials
Carbon and Low-Alloy Steel Forgings, Requiring Notch Toughness Testing for Piping Components
Scope: This specification2 covers several grades of carbon and low-alloy steel forged or ring-rolled ¯anges, forged fittings and valves intended primarily for low-temperature service and requiring notch toughness testing.

Chemical Composition
Element	Composition, wt. %
	Grade LF1	Grade LF2	Grade LF3	Grade LF5	Grade LF6	Grade LF9	Grade LF787
Carbon, max	0.3	0.3	0.2	0.3	0.22	0.2	0.07
Manganese	0.60±1.35	0.60±1.35	0.90 max	0.60±1.35	1.15±1.50	0.40±1.06	0.40±0.70
Phosphorus,max	0.035	0.035	0.035	0.035	0.025	0.035	0.025
Sulfur, max	0.04	0.04	0.04	0.04	0.025	0.04	0.025
Silicon	0.15±0.30	0.15±0.30	0.20±0.35	0.20±0.35	0.15±0.30		0.40 max
Nickel	0.40 max	0.40 max	3.3±3.7	1.0±2.0	0.40 max	1.60±2.24	0.70±1.00
Chromium	0.30 max	0.30 max	0.30 max	0.30 max	0.30 maxB,C	0.30 max	0.60±0.90
Molybdenum	0.12 max	0.12 max	0.12 max	0.12 max	0.12 maxB,C	0.12 max	0.15±0.25
Copper	0.40 max	0.40 max	0.40 max	0.40 max	0.40 max	0.75±1.25	1.00±1.30
Columbium	0.02 max	0.02 max	0.02 max	0.02 max	0.02 max	0.02 max	0.02 min
Vanadium	0.08 max	0.08 max	0.03 max	0.03 max	0.04±0.11	0.03 max	0.03 max
Nitrogen					0.01±0.030

Mechanical Properties
	Grades
	LF1 and LF5	LF2	LF3	LF6		LF9	LF787
	Class 1	Classes 1 and 2	Classes 1 and 2				Class 2	Class 3
			LF5	Class 1	Classes 2 and 3
Tensile strength, ksi [MPa]	60±85	70±95	70±95	66±91	75±100	63±88	65±85	75±95
	[415±585]	[485±655]	[485±655]	[455±630]	[515±690]	[435±605]	[450±585]	[515±655]
Yield strength, min, ksi [MPa]	30 [205]	36 [250]	37.5 [260]	52 [360]	60 [415]	46 [315]	55 [380]	65 [450]
Elongation:
Standard round specimen, or small proportional specimen, min % in 4D gage length	25	22	22	22	20	25	20	20
Strip specimen for wall thickness 5¤16 in. [7.94 mm] and over and for all small sizes tested in full section; min % in 2 in. [50 mm]	28	30	30	30	28	28	28	28
Equation for calculating min elongation for strip specimens thinner than 5¤16  in. [7.94 mm]; min % in 2 in. [50 mm] t = actual thickness in inches	48t + 13	48t + 15	48t + 15	48t + 15	48t + 13	48t + 13	48t + 13	48t + 13
Reduction of area, min, %	38	30	35	40	40	38	45	45

1.1This specification 2 covers several grades of carbon and low-alloy steel forged or ring-rolled ¯anges, forged fittings and valves intended primarily for low-temperature service and requiring notch toughness testing. They are made to specified dimensions, or to dimensional standards, such as the ASME and API specifications referenced in Section 2. Although this specification covers some piping components machined from rolled bar and seamless tubular materials (see 5.3.3), it does not cover raw material produced in these product forms.
1.2No limitation on size is intended beyond the ability of the manufacturer to obtain the specified requirements. How-ever, Class 3 of Grade LF787 is only available in the quenched-and-precipitation heat treated condition.
1.3Supplementary requirements are provided for use when additional testing or inspection is desired. These shall apply only when specified by the purchaser in the order.