1.Performance parameters and usage of.40Cr seamless steel pipe:
40Cr seamless steel tube is one of the most widely used seamless steel tubes in machinery manufacturing industry. 40Cr seamless steel tube after quenching and tempering has good comprehensive mechanical properties, good low temperature impact toughness and low notch sensitivity. 40Cr seamless steel pipe has good hardenability. It can be quenched to 28 ~ 60mm when water quenched, and can be quenched to 15 ~ 40mm when oil quenched. 40Cr seamless steel pipe is also suitable for cyanide and high frequency quenching treatment besides quenching and tempering. The cutting performance is better. When the hardness of 40Cr seamless steel pipe is 174 ~ 229HB, the relative machinability is 60%.
2.40Cr Seamless Steel Tube Manufacturing Method:
40Cr seamless steel tube billet should be manufactured by continuous casting or hot rolling (forging), and ingot can also be directly used as billet. 40Cr seamless steel pipe shall be manufactured by hot rolling (extrusion, expansion) or cold drawing (rolling) seamless method. When the buyer specifies a method for manufacturing, it shall be specified in the contract. Delivery status of 40Cr seamless steel pipes: Hot rolled (extruded, expanded) steel pipes shall be delivered in hot rolled or heat treated state. When delivery is required in heat treated state, it shall be specified in the contract. Cold-drawn (rolled) steel pipes should be delivered in heat treatment state. According to the requirement of the demander, after consultation between the supplier and the demander, it is indicated in the contract that cold-drawn (rolled) steel pipes can also be delivered in cold-drawn (rolled) state.
3. Mechanical properties and chemical composition of 40Cr seamless steel tube:
Chemical composition and mechanical properties: composition: silicon 0.17~0.37%, Mn 0.5~0.8, chrome 0.8~1.1%
Quenching and tempering treatment: sample diameter: 25mm, 850 degree quenching, heating oil quenching, 520 degree tempering: tensile 1000 MPa, yield 800 MPa, elongation 9%, section contraction 45%, impact toughness 588 thousand and 300 coke / square meter.
Because of their different manufacturing processes, they are divided into two types: hot rolled (extruded) seamless steel tube and cold drawn (rolled) seamless steel pipe. Cold drawn (rolling) pipes are divided into two types: circular and special-shaped tubes.
4. 40Cr seamless steel pipe hardness test:
40Cr Seamless steel pipe in annealing or high temperature state delivery, and wall thickness is not greater than 5mm alloy structural steel pipe, its Brinell hardness should conform to the mechanical properties of the provisions.
5. 40Cr seamless steel pipe flattening test:
The seamless steel pipe made of 10,15,20,25,20mn,q235,q275,q295,q345 steel, with an outer diameter of >22mm-400mm and a ratio of wall thickness to outer diameter not greater than 10% shall be tested for flattening.
6.40Cr seamless steel pipe surface quality:
40Cr seamless steel pipe internal and external surfaces are not allowed to have visual visible cracks, folding, scarring, rolling and separation. These defects should be completely removed. The removal depth should not exceed the negative deviation of the nominal wall thickness. The actual wall thickness of the cleaning site should be not less than the allowable minimum deviation of wall thickness deviation, and other local defects that do not exceed the wall thickness deviation are allowed to exist.
7.40Cr seamless steel pipe outer diameter and wall thickness allowance deviation:
Deviation grade standardization outer diameter allowable deviation
D1 + 1.5%, minimum + 0.75 mm
D2 + 1%. Minimum + 0.50 mm
D3 + 0.75%. minimum + 0.30 mm
D4 + 0.50%. Minimum + 0.10 mm
8.non destructive testing of.40Cr seamless steel tubes:
40Cr seamless steel pipe can be negotiated by the supplier and the buyer according to the requirements of the buyer, and it is indicated in the contract that the steel pipe can be carried out non-destructive testing by one or more methods in the following methods or other methods for non-destructive testing. 1, ultrasonic inspection is carried out according to the regulations of GB/T5777, the size of artificial defects, the cold drawn (rolled) steel pipe is L3 (C10), and the hot rolled (extruded and expanded) steel pipe is L4 (C12).2. The eddy current inspection is carried out according to the regulations of GB/T7735, the acceptance level is A.3, and the magnetic flux inspection is carried out according to the provisions of GB/T12606, and the acceptance level is L4..