1. Material Overview
30CrMnSiA steel pipe is a pipe made of 30CrMnSiA alloy steel. 30CrMnSiA is positioned as a high-strength and high-toughness military alloy structural steel. Its national military standard is GJB2150A-2005 special technical conditions. Tianjin 30CrMnSiA seamless steel pipe product implementation standards include XYTG1309.7-2017, GJB2051A-2015, etc.
2. Chemical composition
The main elements that affect the performance of 30CrMnSiA steel plate (the material is consistent with the steel pipe) include C, Si, Mn, P, S, etc. The content of C element is 0.28% - 0.34%, which can improve strength and hardness, but reduce toughness; the content of Si element is 0.80% - 1.10%, which can improve strength and corrosion resistance; the content of Mn element is 0.80% - 1.10%, which can improve strength and toughness; the content of P and S elements does not exceed 0.035% and 0.035% respectively, which helps to improve toughness. In addition, the content of Cu, Ni, Cr, Mo and other elements is 0.30% - 0.50%, 0.20% - 0.50%, 0.80% - 1.10%, 0.10% - 0.30% respectively, which can improve strength and corrosion resistance.
3. Mechanical properties
Strength and hardness: The yield strength and tensile strength of 30CrMnSiA military steel are 800MPa and 900MPa respectively, and the hardness range is between 24HRC and 32HRC. There are also data showing that its yield strength is 165-220MPa, and its tensile strength is 217-284MPa
Other properties: Mechanical performance indicators such as elongation, impact toughness, cross-sectional shrinkage and bending limit are excellent, which can meet the requirements of military equipment in terms of impact resistance, fatigue resistance and corrosion resistance. For example, its elongation is 16.7%-24.2%, and its impact toughness at -40℃ is ≥88J.
4. Characteristics
Advantages: It is a high-strength quenched and tempered structural steel with high strength and toughness, high hardenability, medium cold deformation plasticity, good cutting performance, good machinability, good corrosion resistance and fatigue strength, small processing deformation, and good fatigue resistance.
Disadvantages: It has a tendency to temper brittleness and poor transverse impact toughness. There are different opinions on welding performance. Some data claim that the welding performance is good, but when the thickness is greater than 3mm, it should be preheated to 150℃ first, and heat treatment is required after welding; some data also claim that the weldability is poor. There is slight decarburization during heat treatment, and there are white spots and overheat sensitivity.
5. Applications
Machinery manufacturing: mostly used to manufacture various important parts with high load and high speed, such as gears, shafts, clutches, sprockets, grinding wheel shafts, sleeves, bolts, nuts, etc.; also used to manufacture wear-resistant parts with low working temperature, variable load welding components, such as blades, valve plates and non-corrosive pipes of high-pressure blowers. In the general machinery industry, it is also used to manufacture transmission gears, main shafts, spindles, rotating shafts, connecting rods, worms, tram shafts, generator shafts, crankshafts, flywheels and large and small forgings.
Turbine manufacturing: used as main shafts and hubs with working temperatures below 400℃ and diameters within 250mm, impellers with thicknesses below 170mm and various important fasteners.
Agricultural machinery: can be used to manufacture wear-resistant parts such as hoe handles and plow shafts
Other fields: in the construction field, it is used for reinforced concrete structures, such as supporting structures and load-bearing structures of buildings such as bridges, highways, and subways; in the petroleum and chemical fields, it is used to manufacture oil pipelines, chemical equipment, etc.; in the aviation and aerospace fields, it is used to manufacture key components such as aircraft landing gear and rocket engines
