What material is the rear axle of the car made of and how is it welded?
The material and welding method of the rear axle vary significantly depending on the vehicle model, purpose (such as heavy-duty trucks or passenger cars), and component functions. It is mainly divided into two categories: cast axle housing and stamped-welded axle housing. The materials and welding processes also differ accordingly.
Main materials of the rear axle
The rear axle of a vehicle is not a single material but is composed of multiple components. The main materials include:
Cast steel: Widely used in rear axle housings of heavy trucks and commercial vehicles, it has high strength, high rigidity, and good load-bearing capacity. It is currently the mainstream in the market. For example, many truck rear axle housings use ZG45 and other cast steel materials.
Ductile iron/spheroidal graphite iron: Often used for casting axle housings, it has a lower cost and good shock absorption, but its strength and crack resistance are lower than cast steel. It is commonly seen in some mid-to-low-end models or specific components.
Alloy steel/high-strength steel: Used for the upper and lower shells of the stamped-welded axle housing and the half-shaft sleeves, such as 16Mn, 40MnB, Q345, etc., it has good welding and toughness.
Aluminum alloy: Increasingly used in high-end passenger cars and lightweight models. For example, the rear axle of the Mercedes-Benz GLE450 uses aluminum alloy, which has the advantages of light weight, corrosion resistance, and good heat dissipation, but the welding process requires high standards.
Special seamless steel tubes: Used for integral drive axle housings, they are made of special steel with tensile strength of up to 680 MPa and yield strength of 550 MPa, through cold expansion forming, without weld seams, and have superior performance.
Gear materials: The planetary gears, half-shaft gears, etc. inside the rear axle usually use 20CrMnTi and other carburized alloy steels to ensure wear resistance and impact resistance.
Welding method of the rear axle
The welding of the rear axle requires the selection of specific welding materials and processes based on the material. The key lies in the ability to resist cracking and match strength:
Welding of cast steel rear axle housing:
Recommended welding materials: WEWELDING600 alloy steel welding rods, with an ultimate tensile strength of up to 860 MPa and high elongation, designed specifically for high-stress cast steel parts, which can effectively prevent weld cracking.
Optional welding materials: J506 welding rods (E5016) can be used for non-critical parts or temporary repairs, but there is a risk of weld cracking, and it is not recommended for important load-bearing components.
Welding method: It is necessary to clean oil stains, make bevels, control heat input, avoid repeated welding, and when necessary, perform preheating and slow cooling.
Welding of cast iron rear axle housing (less common, mostly seen in older models or tractors):
Recommended welding materials: WEWELDING777 cast iron welding rods, using cold welding technology, no preheating is required, and the crack resistance is excellent, it is the preferred choice for repairing cast iron parts.
Precautions: Ordinary welding rods are prone to causing brittle cracking, cast iron parts are not suitable for repeated welding, otherwise, they are prone to "welding failure".
Welding of stamped-welded axle housing (steel plates):
Mainly use gas protection welding (MIG/MAG) or manual arc welding, the welding materials match the base material, such as ER70S-6 welding wire or J507 welding rods.
The connection between the half-shaft sleeve and the axle housing often uses plug welding to enhance connection strength.
Welding of aluminum alloy rear axle:
Special aluminum welding wires (such as ER4043 or ER5356) and TIG welding process are required.
Before welding, the oxide film must be thoroughly removed, during welding, the temperature must be strictly controlled to prevent deformation and hot cracks.
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