AISI 4340 is a highly alloyed steel with high nickel and chromium content which assures deep hardening when oil quenched, with high strength characteristics throughout the section. Used for heavily stressed parts operating under strenuous conditions. This is also known as Annealed/Q (Annealed Quenched and Tempered).
How strong is 4340?
930 – 1080 Mpa
4340 is a 1.8% nickel – chromium – molybdenum high hardenability high tensile steel – generally supplied hardened and tempered in the tensile range of 930 – 1080 Mpa (condition U) – (Rc 28 – 36).. Characterised by high strength and toughness in relatively large sections.
How do you anneal 4340 steel?
Annealing. To obtain a pearlitic structure on certain parts for machining, 4340 should be annealed at a nominal temperature of 1525 º F (830 º C,) cooling to 1350 º F (730 º C) and furnace cooling to 1130 º F (610 º C) at a rate of 20 º F (11 º C) per hour, then air cooling.
How hard can you heat treat 4340 steel?
Atlas 4340 can be surface hardened to 58HRC (water quench) or surface hardened to between 53 to 55HRC (oil quench). Tempering at 200°C. Welding is not recommended because of the danger of quench cracking. If welding must be carried out, pre-heat to 200 to 300°C and maintain this while welding.
What is the hardness of 4340 steel?
280-320HB
AISI 4340 steel is generally supplied in hardened and tempered condition with the tensile range of 930 – 1080 Mpa ,hardness 280-320HB.
What is the hardness of 4140 annealed?
200 Brinell
Annealed Alloy Steel Métaux Solutions 4140 Annealed is a high-quality, 4140 alloy steel intended for all mechanical uses where improved machinability, uniform hardness and excellent flatness are required. Product hardness-typically 200 Brinell.
What does AISI 4340 mean?
AISI 4340 is a heat treatable, low alloy steel containing nickel, chromium and molybdenum. It is known for its toughness and capability of developing high strength in the heat treated condition while retaining good fatigue strength. Applications.
Why does annealing soften a material?
In annealing, atoms migrate in the crystal lattice and the number of dislocations decreases, leading to a change in ductility and hardness. With knowledge of the composition and phase diagram, heat treatment can be used to adjust from harder and more brittle to softer and more ductile.
Is 4340 machinable?
AISI 4340 alloy steel can be machined using all conventional techniques. Machining process can be performed in the annealed or normalized and tempered conditions.
Is AISI 4340 Corrosion resistant?
4340 Alloy Steel, Among Other Alloys, is Known for its Toughness. Combining strength and toughness with atmospheric corrosion resistance and wear resistance, 4340 alloy steel is commonly used in forged hydraulic and other machine applications as well as the aerospace industry.
What are the mechanical properties of AISI 4340 alloy steel?
The mechanical properties of annealed AISI 4340 alloy steel are displayed in the following table. Properties. Metric. Imperial. Tensile strength. 745 MPa. 108000 psi. Yield strength. 470 MPa.
What is the annealing process for steel 4340?
The alloy usually comes in the annealed condition unless specified otherwise. The standard annealing process for Steel 4340 starts at 1525 °F (830 °C), followed by cooling to 1350 °F (730 °C), and furnace cooling to 1130 °F (610 °C) at 11 °F (20 °C) per hour, followed by air cooling to room temperature.
What is the stress relief of steel 4340?
For tempered-condition material, the stress relief should be 60 °F (15 °C) lower than the tempering temperature. Dramatically improved tensile strength and toughness properties of Steel 4340 can be obtained depending on the heat treatment used. The alloy usually comes in the annealed condition unless specified otherwise.
Can steel 4340 be welded?
Steel 4340 also possesses excellent ductility in the annealed condition. For the best mechanical properties, the material should be welded in the annealed condition. Furthermore, welding should be outright avoided in the hardened and tempered condition since there is a danger of quench cracking.
