1. Material properties and standard specifications
34CrMo4 is a chromium-molybdenum alloy structural steel, which is often used to manufacture high-pressure gas cylinders, cylinders and other parts with strict performance requirements. From the perspective of standard specifications, it is one of the alloy steel materials clearly specified in the European standard EN 10083-3, and also meets the relevant requirements of the Chinese standard GB 18248, which undoubtedly provides a reliable guarantee for its quality and performance. It has high strength, excellent heat resistance and fatigue resistance. The standards for the implementation of 34CrMo4 seamless steel pipes for gas cylinders are relatively diverse, covering multiple national and international standards. These include
Chinese standard: GB/T 18248-2021 (for gas cylinder tubes only)
European standard: EN 10083-3/EN 10297-1
International standard: ISO 11120
American standard: ASTM A372/A372M-3
Japanese standard: JIS G 3429
2. Chemical composition control (%)

Element	C	Si	Mn	P≤	S≤	Cr	Mo	ohther
Content	0.30-0.37%	≤0.40%	0.60-0.90%	0.020%	0.020%	0.90-1.20%	0.15-0.30%	Ni≤0.30% Cu≤0.20%

Note: Total phosphorus and sulfur ≤ 0.030%

3.Excellent mechanical performance

After heat treatment and tempering (quenching + tempering), 34CrMo4 seamless steel pipe has a tensile strength of ≥980MPa, a yield strength of ≥835MPa, and an elongation of ≥12%. At a low temperature of -50°, the impact energy can still be ≥27J.

4. Key points of production process
1. Manufacturing process:
Using hot rolling/cold drawing seamless process → ultrasonic flaw detection (UT) → quenching and tempering (quenching + tempering) → hydraulic test → finished product inspection
2. Delivery status:
Generally delivered in rolled or cold drawn state, final heat treatment is required after processing by the end user
5. Correspondence between domestic grades
34CrMo4 retains the same name in Chinese standards, and its performance is equivalent to:
GB/T 3077: 34CrMo
Similar grades: 42CrMo (composition needs to be adjusted)
6. Typical application areas

Industry	Specific application	Performance requirements
Energy storage and transportation	CNG/LPG cylinders, hydrogen storage cylinders	High pressure bearing (20-35MPa)
Medical equipment	Medical oxygen cylinders	High purity (low S/P content)
Firefighting equipment	Respirator cylinders, fire extinguisher cylinders	Low temperature impact toughness
Transportation	Commercial vehicle brake system cylinders	Anti-vibration fatigue
Military and aerospace	Propellant tanks	Ultra-fine grain processing

7.Conventional product specifications (mm)

Outer diameter range: Φ108-356
Wall thickness range: 4-16.8
Typical sizes:
Φ139.7×4.5, Φ203×5.4, Φ279×6.8, Φ355.6×7.5, etc.
(Non-standard size customization is supported)
8. Main application areas of 34CrMo4
34CrMo4, as a chromium-molybdenum steel alloy material, is mainly used for the production of seamless steel pipe materials for high-pressure gas cylinders/steel cylinders and high-pressure containers. In practical applications, it is mainly used in the manufacture of CNG cylinders, including the manufacture of compressed natural gas cylinders for vehicles and other high-pressure container cylinders, providing reliable material support for these fields.