SAE AMS 6359L 4340 Alloy Steel Flat Bar

Product Detail

4340 Alloy Steel Flat Bar 10×400×700mm | Q&T Plate with Verified MTC Data

4340 alloy steel flat bar is a high-strength nickel-chromium-molybdenum alloy steel product supplied in hot rolled quenched and tempered condition. Based on the verified mill test certificate, this batch offers controlled chemical composition, high yield and tensile strength, good impact toughness, stable delivery hardness, fine grain size, and qualified ultrasonic inspection. It is suitable for machining, tooling bases, support plates, heavy-duty machinery parts, and other critical engineering applications. This batch is available in 10×400×700mm size and is produced by EAF + LF + VD refining, providing cleaner steel quality and reliable internal soundness for industrial buyers looking for 4340 alloy steel plate, 4340 alloy steel flat bar, or 4340 Q&T steel plate.

Product Overview

4340 alloy steel is widely used where high strength, hardenability, and toughness are required. Compared with common structural steels, 4340 offers better response to heat treatment and more reliable mechanical performance under demanding load conditions. This makes it suitable for parts that require both strength and impact resistance. Unlike ordinary annealed stock, this batch is delivered in quenched and tempered condition, which means the product is already processed to provide improved strength and toughness. According to the actual MTC data, the tested yield strength reaches 928–964 MPa, tensile strength reaches 1061–1091 MPa, elongation is 18%, and impact energy reaches 53.0–55.3 J.

Why Choose This 4340 Alloy Steel Flat Bar

Verified high strength: Yield strength 928–964 MPa and tensile strength 1061–1091 MPa.
Good toughness: Impact energy 53.0–55.3 J for demanding industrial use.
Stable hardness: Delivery hardness controlled at approximately 33.5–34.1 HRC.
Clean steel quality: Produced by EAF + LF + VD with low phosphorus and sulfur.
Qualified internal quality: Grain size, inclusion, macrostructure, and ultrasonic testing available.
Full traceability: Heat No., Production No., and Mother Heat No. recorded on the MTC.

Basic Product Information

Item	Value
Steel Grade	4340
Product Form	Plate / Flat Bar
Size	10.00 × 400.00 × 700.00 mm
Delivery Condition	Hot Rolled Quenched and Tempered
Specification	Z034-2022C
Smelting Method	EAF + LF + VD
Heat No.	422V2-756
Production No.	2205-404-ZCM8462
Mother Heat No.	4225-1040

Chemical Composition

Element	Standard Requirement (%)	Actual Value (%)	Compliance
C	0.38 – 0.43	0.41	Yes
Si	0.15 – 0.35	0.25	Yes
Mn	0.60 – 0.80	0.76	Yes
P	0.00 – 0.035	0.006	Yes
S	0.00 – 0.04	0.003	Yes
Cr	0.70 – 0.90	0.83	Yes
Mo	0.20 – 0.30	0.26	Yes
Ni	1.65 – 2.00	1.83	Yes

The tested chemistry confirms a balanced 4340 Ni-Cr-Mo alloy system. Low phosphorus and sulfur content help improve steel cleanliness and reliability, while the Ni-Cr-Mo combination supports strong hardenability and stable mechanical performance.

Mechanical Properties

Property	Requirement	Actual Result	Compliance
Yield Strength Rp0.2	≥ 850 MPa	928 / 964 MPa	Yes
Tensile Strength Rm	≥ 900 MPa	1061 / 1091 MPa	Yes
Elongation A	≥ 18%	18.0 / 18.0 %	Yes
Impact Energy KV2	≥ 45 J	55.3 / 53.0 J	Yes

Delivery Hardness

Test Item	Actual Result
Delivery Hardness (HRC)	33.5, 33.7, 33.9 / 33.6, 33.8, 34.1

The hardness results are narrow and consistent, showing good process control and stable batch performance for customers requiring reliable 4340 quenched and tempered steel plate.

Inspection and Quality Assurance

Inspection Item	Result
Non-metallic Inclusion	Qualified
Austenitic Grain Size	Grade 8.0
Macrostructure Examination	Qualified
Ingot Segregation	0.5 / 0.5
Scattered Porosity	0.5 / 0.5
Central Porosity	0.5 / 0.5
Ultrasonic Test	GB/T 4162 Class A Qualified
Surface, Size and Shape	Qualified

Verified Material Highlights

Grade: 4340
Size: 10×400×700 mm
Condition: Hot Rolled + Quenched and Tempered
Refining: EAF + LF + VD
Yield Strength: 928–964 MPa
Tensile Strength: 1061–1091 MPa
Elongation: 18%
Impact Energy: 53.0–55.3 J
Hardness: 33.5–34.1 HRC
Grain Size: Grade 8.0
UT Inspection: GB/T 4162 Class A Qualified
Traceability: Heat No. / Production No. / Mother Heat No. available

Applications

The 4340 alloy steel flat bar 10×400×700mm is suitable for a wide range of heavy-duty and precision engineering applications, including:

Structural support plates
Heavy machinery parts
Tooling bases
Fixture plates
Backing plates
Load-bearing steel components
Custom machining stock
Engineering parts requiring both strength and toughness

FAQ

What is 4340 alloy steel flat bar used for?

4340 alloy steel flat bar is widely used for high-strength structural and mechanical parts, including tooling bases, support plates, machinery components, and custom machined parts that require toughness and strength.

Is this 4340 material supplied in heat treated condition?

Yes. According to the mill test certificate, this batch is supplied in hot rolled quenched and tempered condition.

What size is available for this batch?

The available size shown on the MTC is 10×400×700 mm.

What are the actual mechanical properties of this 4340 plate?

The tested values are yield strength 928 / 964 MPa, tensile strength 1061 / 1091 MPa, elongation 18.0%, and impact energy 55.3 / 53.0 J.

What is the hardness of this 4340 alloy steel flat bar?

The delivery hardness is approximately 33.5–34.1 HRC.

Does the material have ultrasonic testing?

Yes. The MTC shows GB/T 4162 Class A ultrasonic test qualified.

Is the chemical composition within standard range?

Yes. The tested chemistry is fully within the listed standard limits, including C 0.41, Si 0.25, Mn 0.76, Cr 0.83, Mo 0.26, Ni 1.83, P 0.006, and S 0.003.

Is full traceability available?

Yes. The MTC includes Heat No., Production No., and Mother Heat No. for reliable batch traceability.

Product Tags

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