Thermal treatment method for low alloy steel

Abstract

The invention relates to a thermal treatment method for low alloy steel. A material is heated to 1020-1080 DEG C and subjected to heat preservation for 10-30 min, thereby converting the material into an austenite completely and dissolving carbides into the austenite. Then, the austenite is subjected to isothermal treatment at 500-380 DEG C for 1-5 h to precipitate the carbides and convert the austenite into lower bainite. Then the lower bainite is subjected to low-temperature tempering at 160-180 DEG C for 0.8-1.5 h and is cooled in air. Compared to the prior art, the low alloy steel treated by the method has not only high hardness, but also good toughness, good wear resistance, small dynamic-load notch sensitivity, high fatigue strength, good casting performance and high rate of finished casting products.

Description

technical field [0001] The invention relates to a heat treatment method for low alloy steel, in particular to a heat treatment method for low alloy steel used as bucket teeth. Background technique [0002] The bucket teeth are generally fixed at the lower end of the excavator bucket, directly contacting the road surface and the material that needs to be scooped up, such as hard things such as sediment, stone, soil, etc., so as to protect the bucket from damage. However, during use, the bucket teeth need to be constantly contacted and rubbed by hard things such as stones and mud, so the bucket teeth are easily worn out after a period of use. [0003] In the prior art, the bucket teeth are generally made of low-carbon alloy steel. Low-carbon alloy steel has good comprehensive mechanical properties and is not easy to break. However, the hardness is generally only about HRC50. After a period of use, the low-alloy The wear of the steel material is relatively serious. When the we...

AI Technical Summary

Problems solved by technology

However, during use, the bucket teeth need to be constantly contacted and rubbed by hard things such as stones and mud, so the bucket teeth are easily worn out after a period of use.

[0003] In the prior art, the bucket teeth are generally made of low-carbon alloy steel. Low-carbon alloy steel has good comprehensive mechanical properties and is not easy to break. However, the hardness is generally only about HRC50. After a period of use, the low-alloy The wear of the steel material is relatively serious. When the wear is too great to play a protective role, it needs to be replaced. Generally, it needs to be replaced within 2 to 3 months. Frequent replacement of bucket teeth not only reduces the efficiency, but also reduces the cost of use. greatly increased; and if the alloy material with higher hardness and high content is used to make bucket teeth, although this alloy material with higher hardness has better wear resistance, the comprehensive mechanical properties are poor, and the higher hardness leads to its brittleness. Larger, it is very easy to break when used; and in order to obtain an alloy material with relatively good wear resistance and relatively good comprehensive mechanical properties, it is necessary to add more alloys for quenching and tempering when the alloy material is smelted, but The use cost of alloying elements is relatively high, and the cost of alloy materials has also increased significantly accordingly.