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How to distinguish between alloy structural steel AISI 4140 and 4130 steel?


Last week, a customer said that he bought 4130 steel from another supplier, but it turned out to be fake. They replaced 4130 steel with 4140 steel, so in order to prevent more people from being deceived, this article mainly talks about the two. Similarities and differences. Before buying these two kinds of steel, you must distinguish between the alloy structural steel AISI 4140 and 4130 steel. What is the difference between 4140 and 4130?

Such steels as AISI 4130 have relatively high requirements for welding and heat treatment, etc. This kind of steel is difficult to buy in stock in China, and most of them need to be customized, especially round steel, which our company provides Customized service of 4130 steel, also provide stock of alloy structural steel AISI 4140.Both AISI 4130 steel and AISI 4140 steel have the characteristics of high strength and toughness, and high hardenability. The critical hardenable diameter of 4130 steel in oil is 15-70mm; the hot strength of steel is also good, and it has sufficient strength under 500 celsius high temperature strength, but the strength drops significantly at 550 celsius; when the alloying element is at the lower limit, the welding is quite good, but when it is close to the upper limit, the weldability is moderate, and it needs to be preheated to above 175 celsius before welding; the machinability of the steel is good, and the cold The plasticity is moderate during deformation; the first type of temper brittleness occurs in the range of 300-350 celsius during heat treatment; there is a tendency to form white spots. Alloy structural steel AISI 4140 has no obvious temper brittleness. After quenching and tempering treatment, it has high fatigue limit and multiple impact resistance, and has good low temperature impact toughness.

The chemical composition of 4140 steel and 4130 steel is very similar, but the allowable residual content ranges of nickel and copper elements are quite different. The nickel and copper elements of 4140 steel are ≤0.30, and the nickel and copper elements of 4140 steel are ≤0.030, and AISI 4130 alloy steel contains chromium and molybdenum as reinforcements.It has low carbon content, so it is easy to weld; in terms of mechanical properties, its elongation δ5 (%), impact energy Akv (J), impact toughness value αkv (J/cm2) The range is the same; in the application In terms of alloy structural steel AISI 4140, it is used to manufacture forgings that require higher strength and larger quenched and tempered sections than 35CrMo steel, such as large gears for locomotive traction, supercharger transmission gears, rear axles, salvage tools, and bending machines. molds, etc.AISI 4130 is mainly used in medium-sized machinery manufacturing to manufacture quenched and tempered parts with large cross-sections that work under high stress conditions, such as shafts, spindles, bolts, gears, etc.; in the chemical industry, it is used to manufacture welded parts, plates and pipes The welded structure formed and the high-pressure conduit whose temperature does not exceed 250 celsius in the medium containing nitrogen and hydrogen; used in the steam turbine and boiler manufacturing industries to manufacture fasteners working below 450 celsius, flanges and flanges under high pressure below 500 celsius Flange cover.

From this point of view, 4140 steel is quite similar to 4130 steel, but we will find the difference if we understand it carefully, so before buying steel, you must know your needs and find a professional supplier. Our company has more than ten years of production experience, rich professional knowledge, cost-effective and high-quality products, and provides various types of alloy steel. You are welcome to consult and purchase.


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