34CrNiMo6+QT steel is a high-strength alloy steel for quenching and tempering, i.e. quenched and tempered (QT). It is widely used in the heavy industry, automotive and aerospace industries, where high strength, hardness and resistance to dynamic loads are required.
34CrNiMo6+QT steel contains carefully selected alloying elements that provide it with excellent mechanical properties after heat treatment. It is characterized by high mechanical properties after quenching and tempering. Thanks to the presence of nickel, molybdenum and chromium, this steel shows very good fatigue resistance and high strength under dynamic loads.
34CrNiMo6+QT steel is subjected to quenching and tempering processes, which provides it with optimal mechanical properties. The hardening process involves rapid cooling of the steel after it has been heated to a high enough temperature to increase its hardness. The steel is then tempered to achieve the desired strength properties and reduce brittleness.
The greatest advantage of this grade of steel is its hardenability; this steel does not exhibit tempering embrittlement. Its disadvantage, however, is poor weldability. Welding is possible, after a softening annealing operation. Depending on the thickness of the workpiece, the workpiece should be heated to about 300-450℃ before welding. It is advisable to make short welds (<25mm). If large workpieces need to be welded, inter-operation annealing should be performed. Immediately after welding, the part should also be softening annealed or heat tempered.
Steel 34CrNiMo6+QT chemical composition
| Designation | C % max | Mn % max. | Si % max | Cr % max | P % max. | S % max. | Ni % max. | Mo % max. | Cu % max. | |
|---|---|---|---|---|---|---|---|---|---|---|
| 34CrNiMo6+QT | 1.6582 | 0,30 - 0,38 | 0,50 - 0,80 | 0,10-0,40 | 1,30-1,70 | 0,025 | 0,035 | 1,30-1,70 | 0,15-0,30 | 0,40 |
Steel 34CrNiMo6+QT mechanical properties
| Steel | Mechanical properties | |||
|---|---|---|---|---|
| Grade | Rp0.2 [MPa] | Rm [MPa] | Elongation % [MPa | Impact strength |
| 34CrNiMo6+QT+SH | 800-900 | 1100-1200 | 10-11 | 40-45 |
| 34CrNiMo6+QT+C | 650-770 | 1000-1200 | 8-10 | |
34CrNiMo6+QT steel applications
Due to its properties, 34CrNiMo6+QT steel is widely used for components that require high strength and resistance to dynamic loads. Typical applications include:
- Drive shafts: Operating under high load and fatigue conditions.
- Gears: Used in gears requiring high wear resistance and durability.
- Aerospace structural components: Where superior strength and reliability are required.
- Machinery industry: Parts of construction and agricultural machinery that must withstand harsh working conditions.
- Shafts, press parts, rings, high-pressure cylinder cover bolts of steam turbines, rotors and disks of steam turbines: Parts subjected to impact, twisting and vibration,
| EU EN | Steel number | AISI USA | Russia |
| 34CrNiMo6+QT | 1.6582 | 4337 | 38Ch2N2MA |
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