Description
Purpose of 42CrMo seamless steel pipe: the special steel for bridge is "42CrMo", the special steel for automobile girder is "42CrMo", and the special steel for pressure vessel is "42CrMo". This kind of steel improves the mechanical properties of steel by adjusting the carbon content (c). Therefore, according to the carbon content, this kind of steel can be divided into: low carbon steel - the carbon content is generally less than 0.25%, such as 10 and 20 steel; Medium carbon steel - the carbon content is generally between 0.25 ~ 0.60%, such as 35 and 45 steel; High carbon steel - carbon content is generally greater than 0.60%. This kind of steel is not generally used in the manufacture of steel pipes.Requirements for different quality levels are as follows
A - provide s, P, C, Mn, Si chemical composition and Fu, FY δ 5（ δ 10) , 1800 cold bending test can be provided according to the buyer's needs, but there is no impact energy regulation, and the carbon content and manganese content are not taken as the delivery conditions. B - provide s, P, C, Mn, Si chemical composition and Fu, FY δ 5（ δ 10) , cold bend 180 'test. Impact energy AK ≥ 27j at + 200C is also provided C - in addition to the requirements of class B, the impact energy AK ≥ 27j at 00C is also provided. D - in addition to the requirements of level B, the impact energy AK ≥ 27j at - 200C is also provided. E -- in addition to the requirements of level B, the impact energy AK ≥ 27j at - 400C is also provided. Hot working specification The heating temperature is 1150 ~ 1200 ° C, the starting temperature is 1130 ~ 1180 ° C, and the ending temperature is > 850 ° C, φ> Slow cooling at 50mm.Normalizing specification
The normalizing temperature is 850 ~ 900 ° C, and the furnace is discharged for air cooling. High temperature tempering specification The tempering temperature is 680 ~ 700 ° C, and the furnace is discharged for air cooling.42CrMo is a kind of steel. Steel used to be called steel. The method is called Q345B. The similar materials are Q345A, Q345C and Q345E. The quality grade symbol a, B, C, d e respectively indicates that impact test is not required. The impact test temperature is + 20 ° 0 ° to 20 ° 40 ° ABCD indicates the quality grade Q235. The quality grade is divided into four grades A, B, C and D. from a to D indicates that the quality is from low to high.
Quenching and tempering specification
Preheating temperature 680 ~ 700 ° C, quenching temperature 840 ~ 880 ° C, oil cooling, tempering temperature 580 ° C, water cooling or oil cooling, hardness ≤ 217hbw. Specification for strengthening and toughening treatment by sub temperature quenching Quenching temperature 900 ° C, tempering temperature 560 ° C, hardness (37 ± 1) HRC Specification for induction quenching and tempering Quenching temperature 900 ° C, tempering temperature 150 ~ 180 ° C, hardness 54 ~ 60HRC.