According to the quenching temperature range, the quenching ductility can be divided into low and high quenching ductility [2]. 

16mn precision steel tube heat treatment quenching ductility temperature range of 250 ~ 400 ℃ of steel quenching embrittlement,

 it is a ductility ductility change temperature significantly higher after individual obtained austenitic aluminum alloy. 

The brittle crack of 16mn precision steel pipe has not yet been quenched, and then heated to remove, 

it is also called irreversible quenching ductility%26rdquo;. 

It is mainly produced in high precision such as carbon steel and high compressive strength high alloy steel. 

People have 16mn precision steel tube brittle fracture is a mixture of intergranular fracture and intergranular or quasi-cleavage fracture. 

The reason for the quenching ductility is generally considered as follows: 

(1) quenching causes the cementite to be massive proto-ferrite grain boundaries in the whole process of grain boundary embrittlement. 

(2) Residue elements such as phosphorus ferrite grain boundary shrinkage are one of the reasons for quenching ductility. 

The purity of phosphorus is less than 0.005%, and the 16mn precision steel pipe does not cause ultra-low temperature quenching ductility. 

The calorific value of ferrite grain boundary in the material is maintained after heat treatment. 

The ductility of the old ferrite grain boundary and the dissolution of phosphorus quenched cementite in the ferrite grain boundary promote the occurrence of ultra-low temperature quenching embrittlement. 

Aluminum alloy elements have a greater harm to the ductility of ultra-low temperature quenching on 16mn precision steel pipes.

 Chromium and manganese promote the residual elements such as phosphorus shrinkage at the ferrite grain boundaries, which in turn promote the ductility of ultra-low temperature quenching. 

Most of tungsten and vanadium are not harmful, and molybdenum reduces the ductility of 16mn precision steel pipes quenched at varying temperatures, 

but not sufficient. The inhibition of quenching ductility. 

The dissolution of silicon quenched cementite can delay the time, and the temperature rise caused by it can improve the precision of the quenching and embrittlement temperature of steel.