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Heavy Duty Alloy Steel Forging Motor Rotor Main Shaft for Large Marine Vessel Transmission System

1.Forming process: Forging

2.Material: 34CrNiMo6 alloy steel

3.Size:φ992*800*4350

4.Weight: 5500kg

5.Lead time：60 days after receiving the advance payment
6.Payment type ：50% after signing the contract, and 50% before shipment
7.Payment terms：FOB/EXW/FCA/CIF，etc
8.Package:：steel pallet
9.MOQ: 1 pcs
10.Service: customized
11.Quality Warranty Certificate: chemical composition and mechanical properties test certificates

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Model:
Forging Transmission Shaft
Brand:
ETERNAL

Product Description

Material Selection

34CrNiMo6 chemical composition

C	Si	Mn	Cr	Ni	Mo	P	S
0.30-0.38%	0.17-0.37%	0.5-0.8%	1.5-1.8%	1.4-1.7%	0.25-0.35%	≤0.025%	≤0.025%

Typical Mechanical Properties (Quenched and Tempered Condition):

Tensile strength: 980–1180 MPa;

Yield strength: ≥835 MPa;

Elongation: ≥12%;

Impact energy: ≥34 J (-10 ℃).

Key Manufacturing Processes

Smelting and Ingot Casting

Electric arc furnace primary smelting → LF refining → VD vacuum degassing → steel ingot pouring.

Control hydrogen content H ≤ 1 ppm and oxygen content O ≤ 25 ppm to reduce inclusions and segregation.

Forging (Core Process)

Heating: Heated at 1100–1200 ℃ with staged preheating to prevent cracking and ensure uniform heat preservation.

Forming: two upsetting-drawing processes (upsetting + stretching); forging ratio ≥ 3, finish forging temperature ≥ 800 ℃ to guarantee continuous metal flow lines.

Cropping: Remove shrinkage cavity and loose segments to ensure internal quality.

Heat Treatment (Performance-Determining Process)

After forging: Normalizing + tempering to refine grain structure and relieve internal stress.

After rough machining: quenching + high-temperature tempering to ensure uniform properties of surface and core, with hardness difference ≤ 3 HBW.

Final treatment: Stress-relief annealing to stabilize dimensions and minimize deformation.

Heat treatment of the motor shaft (2).jpg

Machining and Inspection

Machining:Rough turning → finish turning → grinding, ensuring coaxiality and circular runout ≤ 0.02 mm.

gantry center machining of the motor shaft.jpg

Inspection: 100% inspection by UT (Ultrasonic Testing), MT (Magnetic Particle Testing) and PT (Penetrant Testing). Dimensional and hardness inspection for every single piece; strength difference of the same part ≤ 70 MPa.

Detailed Product Photo

Application

Marine main propulsion motor,

transverse thruster motor,

power station generator rotor main shaft

Feature

High Toughness Material: Adopted 34CrNiMo6 steel, produced via electric arc furnace melting, secondary refining and vacuum degassing. Extremely low impurities with S, P ≤ 0.025%. It features high strength, excellent toughness, fatigue resistance and seawater corrosion resistance.

Large Dimension and Heavy Weight.

Superior Forged Microstructure: Adopted open die forging plus two upsetting and drawing operations with a forging ratio ≥ 3. The metal flow line is continuous and dense; porosity and shrinkage cavities are fully eliminated. Its fatigue service life is far superior to castings.

Severe Load Conditions: During operation, it withstands high torque, alternating bending stress, centrifugal force and thermal stress, requiring high reliability, low vibration and long service life.

Classification Society Certification: Comply with specifications of ABS, LR, DNV and other marine classification societies. Pass non-destructive testing (UT/MT/PT) and mechanical performance tests.

Certificate