In order to obtain good comprehensive mechanical properties, the following approaches can be taken separately:
(1) Low-carbon (alloy) steel is selected, and after quenching, tempering is performed at a low temperature of 250 ° C or lower to obtain low-carbon martensite. In order to improve the surface wear resistance of such steels, only the carbon content of each surface layer is increased, that is, surface carburization is performed, which is generally called carburized structural steel.
(2) Adopt medium carbon steel with high carbon content, and temper at high temperature (500-650 °C) after quenching (so-called quenching and tempering treatment), so that it can maintain sufficient strength under high plasticity, generally called this The steel is a quenched and tempered steel. If you want to obtain high strength, but prefer to reduce plasticity and toughness, you can take low-temperature tempering for gold-containing quenching and tempering with lower carbon content, so you get the so-called "super high strength."
Degree steel".
(3) Steel grades with carbon content between medium carbon and high carbon (such as 60 and 70 steel) and some high carbon steels (such as 80 and 90 steel), if used to manufacture springs, to ensure high elastic limit , yield limit and fatigue limit, then use medium temperature temper after quenching.
Second, the operation process
(1) Quenched and tempered steel
1. Pre-heat treatment: normalizing→annealing (pearlitic steel)→high temperature tempering (martensitic steel)
The purpose of normalizing is to refine the grain, reduce the degree of banding in the structure, and adjust the hardness to facilitate mechanical processing. Immediately after normalizing, it has equiaxed fine grains.
2. Quenching: The cylinder is heated to about 850 °C for quenching. The quenching medium can be selected according to the size of the steel and the hardenability of the steel. Generally, water or oil or even air quenching can be selected. Steel in quenched state, low plasticity and large internal stress
Read more:https://www.lizhan-hardware.net/
(1) Low-carbon (alloy) steel is selected, and after quenching, tempering is performed at a low temperature of 250 ° C or lower to obtain low-carbon martensite. In order to improve the surface wear resistance of such steels, only the carbon content of each surface layer is increased, that is, surface carburization is performed, which is generally called carburized structural steel.
(2) Adopt medium carbon steel with high carbon content, and temper at high temperature (500-650 °C) after quenching (so-called quenching and tempering treatment), so that it can maintain sufficient strength under high plasticity, generally called this The steel is a quenched and tempered steel. If you want to obtain high strength, but prefer to reduce plasticity and toughness, you can take low-temperature tempering for gold-containing quenching and tempering with lower carbon content, so you get the so-called "super high strength."
Degree steel".
(3) Steel grades with carbon content between medium carbon and high carbon (such as 60 and 70 steel) and some high carbon steels (such as 80 and 90 steel), if used to manufacture springs, to ensure high elastic limit , yield limit and fatigue limit, then use medium temperature temper after quenching.
Second, the operation process
(1) Quenched and tempered steel
1. Pre-heat treatment: normalizing→annealing (pearlitic steel)→high temperature tempering (martensitic steel)
The purpose of normalizing is to refine the grain, reduce the degree of banding in the structure, and adjust the hardness to facilitate mechanical processing. Immediately after normalizing, it has equiaxed fine grains.
2. Quenching: The cylinder is heated to about 850 °C for quenching. The quenching medium can be selected according to the size of the steel and the hardenability of the steel. Generally, water or oil or even air quenching can be selected. Steel in quenched state, low plasticity and large internal stress
Read more:https://www.lizhan-hardware.net/
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