GB/T 3639 Seamless Steel Tubes For Precision Application

Instruction

GB/T 3639 Seamless Steel Tubes For Precision Application

 

Material and Specification
The GB/T 3639 standard covers seamless cold-drawn or cold-rolled steel tubes used for precision applications. These tubes are available in various steel grades and dimensions to suit different industrial requirements. The main material used for manufacturing these tubes is carbon steel and alloy steel.

 

Chemical Composition
The chemical composition of the steel used in GB/T 3639 seamless tubes for precision application is crucial in determining the material's properties and performance. The table below presents the typical chemical composition (in percentage) of the main steel grades used:

Steel Grade	C	Si	Mn	P	S	Cr	Ni
10	0.07-0.13	0.17-0.37	0.35-0.65	≤0.035	≤0.035	-	-
20	0.17-0.24	0.17-0.37	0.35-0.65	≤0.035	≤0.035	-	-
35	0.32-0.39	0.17-0.37	0.50-0.80	≤0.035	≤0.035	-	-
45	0.42-0.50	0.17-0.37	0.50-0.80	≤0.035	≤0.035	-	-
16Mn	0.12-0.20	0.20-0.55	1.20-1.60	≤0.035	≤0.035	-	-
25Mn	0.22-0.29	0.17-0.37	0.70-1.00	≤0.035	≤0.035	-	-

 

Mechanical Properties
The mechanical properties of GB/T 3639 seamless steel tubes play a vital role in ensuring their suitability for precision applications. The following table outlines the typical mechanical properties of the main steel grades:

Steel Grade	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation (%)	Hardness (HB)
10	335-475	≥205	≥25	≤100
20	410-550	≥245	≥20	≤100
35	510-690	≥305	≥17	≤100
45	590-835	≥335	≥14	≤110
16Mn	540-735	≥345	≥14	≤95
25Mn	590-835	≥390	≥10	≤120

 

Steel Grade and Application

GB/T 3639 seamless steel tubes are available in various steel grades, each serving specific applications in different industries. Below are some common steel grades and their respective applications:

Steel Grade 10: Suitable for general precision machinery, automotive parts, and mechanical engineering applications.

Steel Grade 20: Used in the manufacturing of hydraulic systems, cylinders, and other precision machinery components.

Steel Grade 35: Ideal for applications requiring higher mechanical properties, such as heavy machinery and equipment.

Steel Grade 45: Suitable for precision components, especially those requiring high tensile strength and wear resistance.

Steel Grade 16Mn: Commonly used in the production of agricultural machinery, construction equipment, and vehicle chassis.

Steel Grade 25Mn: Applied in precision instruments and meters, as well as various machinery and equipment.