In order to better improve the tensile strength and wear resistance of the surface of Q345D seamless steel pipe, we need to carry out some surface treatment of metal materials during the production process. Are there any characteristics of Q345D seamless steel pipe?
Model specification reliability For precision machining of rectangular square tubes, precision machining is required, so the model specification reliability is deliberately maintained. Because it is straightened on the vapor body, the cooling speed is relatively slow, so it has a relatively stable effect, and it will increase the total number of remaining rectangular square tubes in the organization, so it is possible to carry out domestic cold violence as much as possible;
What are the advantages of the heat treatment method of Q345D seamless steel pipe?
It is very important to control the deformation of the heat treatment method as strictly as possible. The whole process of the heat treatment method is particularly important. During the whole process of the heat treatment method, the use of cold plastic to carry out immediate adjustment, this It is to ensure an excellent precondition of the increase rate, so it is reasonable to specify the cooling time in the heat treatment method in the hot bath or in the calibration of the oil burning. In addition, the temperature should be raised according to the suspension system to reduce the deformation of the heat treatment method. For precision machining slides, liquid carbon dioxide induction hardening or ion nitriding should be used to reduce deformation.
Q345D seamless steel pipe is mainly affected by contact fatigue load, so it has as high tensile strength as possible, so heat treatment method, or quenching heat treatment or organic chemical heat treatment method should be carried out, and then ultra-low temperature heat treatment process should be carried out.
The electric welding crack of the Q345D seamless steel pipe is a serious production and processing defect, which will reduce the total area of the welding cross-section and cause the bearing stress. Welding cracks are generally divided into vertical and horizontal. Vertical cracks are the most common in the notch of the molten pool. Because the notch of the molten pool is not fully covered, it is very easy to deposit harmful residues, which reduces part of the plasticity. And the notch is welded to the final condensation place during cooling, and the stress of cooling is also concentrated here. Transverse cracks are generally more common in carbon steel welding. Low-carbon environmental protection programs are also likely to cause lateral cracks when the cooling is too fast or the cooling is uneven.
The factors that cause the welding cracks of Q345D seamless steel pipe are as follows:
(1) The high cooling rate during electric welding is very prone to cracks. Therefore, it is necessary to bypass the air outlet and prevent it from being wetted by precipitation when welding. In electric welding, medium carbon steel or carbon steel, according to the chemical composition or characteristics of the raw material, some of them must be heated and insulated before welding.
(2) The unreasonable welding sequence is also very prone to cracks. When the sequence is not allocated, there will be a deadlock of the welding force receiving force, which prevents the welding from being folded at will, and even causes a large folded ground stress and causes welding cracks.
(3) It is related to the composition of the seamless square tube, the crystal structure, and the method of the smelter. For example, the higher the carbon content of the steel or the higher the amount of aluminum alloy, the higher the strength of the stainless steel sheet, and the easier it is to crack during electric welding.
(4) When the ambient temperature is low during electric welding, or the heat removal standard at the air outlet is too good, the heat removal is too fast, which will also cause cracks.
(5) Causes of electric welding cracks in Q345D seamless steel pipes by electric welding The commonly used welding wires with high sulfur content, phosphorus and carbon are very prone to cracks. Sulfur and phosphorus are harmful elements. High sulfur content has hot ductility for welding, and high phosphorus content welding has cold ductility. The sulfur content of the welding wire needs to be below 0.0035.