Carburizing is a chemical heat treatment technology, carburizing A335 P11 alloy steel surface to obtain carbon content, after quenching and tempering treatment, can ensure that the heart has a certain strength and toughness under the premise of raising P11 Alloy steel pipe surface hardness, wear resistance and fatigue strength, etc., in order to obtain excellent comprehensive mechanical properties.

So the purpose of carburizing after heat treatment is mainly reflected in the following aspects:

① improve the A335 P11 alloy steel pipe surface infiltration layer strength, hardness, wear resistance and fatigue strength;

② to eliminate the infiltration layer in the network of cementite and the appropriate reduction in the number of retained austenite, reduce the brittleness and contribute to A335 P11 alloy steel pipe performance improvement;

③ eliminate the internal stress, increase the size of A335 P11 alloy steel pipe stability, can prevent the quenching Ping turning; to prevent thick-walled A335 P11 alloy steel pipe cutting process caused by the processing of stress caused by the accuracy or size changes;

④ refinement of grain, improve A335 P11 alloy steel pipe toughness. Can withstand the role of heavy loads.