Medium Carbon 45# Hexagonal Bar GB/T 699 for Shaft & Gear Manufacturing

Good comprehensive mechanical strength after heat treatment
Excellent machinability for cutting & machining operations
Stable chemical composition per GB/T 699 standard
Available in cold drawn bright surface & hot rolled black finish
Wide size range for machinery and structural component fabrication

Product Overview

Our 45# Hexagonal Bar is medium carbon hexagonal steel bar manufactured in accordance with GB/T 699 national standard. It can be produced by hot rolling or cold drawing process. The material features balanced strength and toughness, which can be further improved via quenching and tempering heat treatment. The cold drawn version delivers precise dimensional tolerance and bright surface, while hot rolled type provides cost-effective supply for general machining. This GB/T 699 45# hex bar is commonly processed into machinery shafts, gears, mold parts and structural components for mechanical engineering industries.

Carbon Steel Hexagonal Bar

Chemical & Mechanical Property Snapshot

Item	Value
Grade	45#
Standard	GB/T 699
Carbon (C)	0.42~0.50%
Silicon (Si)	0.17~0.37%
Manganese (Mn)	0.50~0.80%
Phosphorus (P), Max	≤0.035%
Sulfur (S), Max	≤0.035%
Min Yield Strength	≥355 MPa
Tensile Strength	≥600 MPa
Elongation (A5 Min)	≥16%

Detailed Technical Specifications

Specification Item	Details
Product Name	45# Hexagonal Bar
Standard	GB/T 699
Material	Medium Carbon Steel
Process	Cold Drawn / Hot Rolled
Surface	Bright cold drawn / Black hot rolled
Size Range (Across Flat)	6mm – 80mm
Dimensional Tolerance	Cold drawn: ±0.02~0.1mm; Hot rolled: ±0.3~1.0mm
MOQ	5 Tons
Lead Time	15-25 working days
Packing	Steel strips bundled, anti-rust paper packing
Delivery Term	FOB, CFR, CIF

Size Dimension Table

Item	Specification
Product Name	Carbon Steel Hexagonal Bar
Across-flat Size (S)	S8, S10, S12, S14, S17, S19, S22, S24, S27, S30, S32, S36, S41, S46, S50, S55, S60, S65, S70, S75, S80, S85, S90, S95, S100
Length	3–6 m standard length; custom cut length available
Tolerance	Cold drawn: h9/h11; Hot rolled: GB/T 705 standard tolerance
Cross Section	Hexagonal solid bar
Surface Finish	Hot-rolled black surface / Cold-drawn bright surface

Product Comparison Table

Comparison Item	45# Hexagonal Bar	S45C Hexagonal Bar	1018 Hexagonal Bar	1045 Hexagonal Bar	S235JR Hexagonal Bar
Equivalent Standard	GB/T 699	JIS G4051	ASTM A108	ASTM A108	EN 10277 (Base EN10025-2)
Material Type	Medium Carbon Steel	Medium Carbon Steel	Low Carbon Steel	Medium Carbon Steel	Low Carbon Structural Steel
Carbon Content (C)	0.42~0.50%	0.42~0.48%	0.14~0.20%	0.43~0.50%	≤0.17%(≤16mm); ≤0.20%(>16mm)
Silicon Content (Si)	0.17~0.37%	0.15~0.35%	≤0.60%	0.15~0.35%	≤0.35% (no minimum required)
Manganese Content (Mn)	0.50~0.80%	0.60~0.90%	0.60~0.90%	0.60~0.90%	≤1.40%
Phosphorus (P) Max	≤0.035%	≤0.030%	≤0.040%	≤0.040%	≤0.035%
Sulfur (S) Max	≤0.035%	≤0.035%	≤0.050%	≤0.050%	≤0.035%
Min Yield Strength (Hot Rolled / Normalized)	≥355 MPa	≥345 MPa	≥205 MPa (Typical 250–330MPa for cold drawn)	≥355 MPa	≥235 MPa (≤16mm)
Tensile Strength	≥600 MPa	570~740 MPa	415–520 MPa	585–700 MPa	360–510 MPa
Elongation (A5 Min)	≥16%	≥17%	≥25%	≥16% (annealed)	≥25%
Manufacturing Process	Cold Drawn / Hot Rolled	Cold Drawn / Hot Rolled	Cold Drawn / Hot Rolled	Cold Drawn / Hot Rolled	Cold Drawn / Hot Rolled
Surface Condition	Bright cold drawn / Black hot rolled	Bright cold drawn / Black hot rolled	Bright cold drawn / Black hot rolled	Bright cold drawn / Black hot rolled	Bright cold drawn / Black hot rolled
Size Range (Across Flat)	6mm – 80mm	6mm – 80mm	6mm – 80mm	6mm – 80mm	6mm – 80mm
Dimensional Tolerance	Cold drawn: ±0.02~0.1mm; Hot rolled: ±0.3~1.0mm	Cold drawn: ±0.02~0.1mm; Hot rolled: ±0.3~1.0mm	Cold drawn: ±0.02~0.1mm; Hot rolled: ±0.3~1.0mm	Cold drawn: ±0.02~0.1mm; Hot rolled: ±0.3~1.0mm	Cold drawn: ±0.02~0.1mm; Hot rolled: ±0.3~1.0mm
Main Application	Machinery shafts, gears, mold parts, structural components	Shafts, gears, hydraulic parts, machinery components	Fasteners, pins, general machinery, welding parts	Axles, gears, machine tool components	European standard structural parts, brackets, frames
Cost Level	Medium-High	Medium-High	Medium	Medium-High	Medium
Feature	Good comprehensive strength, can be heat treated	Good hardness & machinability, suitable for quenching & tempering	Excellent weldability & ductility, easy bending	High tensile strength, good heat treatment performance	Excellent weldability, CE compliance, general structural use

App Market

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Product Packaging

Secure Export Packaging For Safe Handling And Delivery

FAQs

What is 45# Hexagonal Bar standard?

Our 45# Hexagonal Bar is produced strictly according to GB/T 699 standard. It is a widely used medium carbon steel hex bar in Chinese steel standard.

Can 45# hexagonal steel bar be heat treated?

Yes. 45# hex bar can perform quenching and tempering treatment to improve hardness and comprehensive mechanical properties for heavy-load machinery parts.

What is the difference between 45# hexagonal bar and S45C hex bar?

45# follows GB/T699, S45C follows JIS G4051. They are close medium carbon steel grades, slight difference in Mn range. S45C has tighter Mn control.

What surface options do you supply?

We supply two types: bright cold drawn surface with tight tolerance, and black hot rolled surface for cost-saving projects.

What is the minimum order quantity?

MOQ is 5 tons, customized sizes are available upon request.

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Medium Carbon 45# Hexagonal Bar GB/T 699 for Shaft & Gear Manufacturing