What is hardened and tempered steel? How many kinds of hardened and tempered steel?
Hardened and tempered steel refers to the heat treatment after quenching and high temperature tempering, which is used for mechanical parts. Heat treatment for harden end and tempered steel is not limited to induction hardening and tempering, but also includes surface treatment, quenching and tempering at medium temperature, quenching and tempering at low temperature, chemical heat treatment. Mechanical parts steel are generally sub-eutectoid steel. Carbon content is 0.25% to 0.5%. Alloying elements in the main plus elements are: Mn, Si, Cr, Ni, B; Supplementary elements are: W, Mo, V. Most of the quality of steel is superior and high quality steel impurity content has strict control.
Quenched and tempered steel is divided into ow hardenability, hardenability and high hardenability.
(1) Low hardenability steel. In this type of steel:
① Water quenching diameter Φ15mm carbon structural steel, such as 35,45 steel.
② Oil quenching diameter Φ20 ~ 40mm alloy steel, the total content of alloying elements in steel <2.5%. After the modulation of the yield strength is at 600 ~ 800MPa.
For example, 40Cr (Φ20-40mm), 38CrSi (Φ30-45mm), 35CrMo (Φ25-40mm), 42CrMo (Φ30-45mm), 35Mn2 (Φ15-30mm), 45Mn2 (Φ20-40mm), 42SiMn 40B (Φ10 ~ 20mm), 40MnB (Φ20 ~ 30mm), 40MnVB (Φ30 ~ 40mm).
38CrMoAI(Nitriding special steel), modulation oil quenching critical diameter is Φ30mm.
(2) Middle hardenability steel. Oil quenching critical diameter is Φ40 ~ 60mm alloy structural steel, usually two or more alloying elements. After the modulation, the yield strength is 800 ~ 1000MPa.
For example, 40CrNi (Φ40 ~ 60mm), 40CrMn (about Φ60mm), 30CrMnSi (Φ40 ~ 50mm).
(3) High hardenability steel. Oil quenching critical diameter is Φ60 ~ 100mm alloy structural steel, containing two or more than three alloying elements, the total amount of alloying elements than the former two. After the modulation, the yield strength IS 850MPa or more.
For example, 30CrNi3A (about Φ200mm), 40CrNiMo (Φ60 ~ 1060mm), 40CrMnMo (about Φ100mm), 35SiMn2MnVA (about Φ100mm).
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Post time: 12-26-2017