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The alloying component in low temperature steel

Reduced temperature steel has superb strength as well as strength in low temperature level atmosphere, great welding performance, machining efficiency as well as deterioration resistance, are generally specified in the minimum temperature level of a certain worth of influence toughness in the standard. In low temperature level steels, components such as carbon, silicon, phosphorus, sulfur as well as nitrogen weaken the durability at low temperature level, among which phosphorus is considered to be one of the most unsafe as well as ought to be dephosphorized at low temperature in very early smelting. Mn, nickel and other elements can boost the strength at reduced temperature. With the boost of nickel web content by 1%, the important change temperature of brittleness can be decreased by about 20 ℃. Low temperature durability, i.e. the ability to stop fragile failure from taking place and also spreading at reduced temperatures, is the most vital aspect. Today we introduce the impact of alloying aspects on the reduced temperature level strength of steel:

C.

With the boost of carbon content, the fragile change temperature of steel boosts rapidly as well as the weldability lowers, so the carbon content of low-temperature steel is limited to much less than 0.2%.

Mn.

The manganese exist in steel with the form of strong option and also can obviously improve the sturdiness of steel at reduced temperature. Additionally, manganese is a component that increases the size of the Austenite region and also reduces the makeover temperature level (A1 and A3). It is simple to get great and also pliable ferrite and pearlite grains, which can maximize the effect power and also reduce the fragile transition temperature. Consequently, the Mn/C ratio need to be at least equivalent to 3, which can not just decrease the breakable change temperature level of steel, but also compensate for the reduction in mechanical properties triggered by the decrease in carbon content as a result of the rise of Mn.

Ni.

Nickel can decrease the brittleness propensity and dramatically decrease the breakable shift temperature. The effect of nickel on enhancing the low temperature durability of steel is 5 times that of manganese. The brittle transition temperature level lowers by 10 ℃ with the boost of nickel content by 1%. This is since the nickel does not react with carbon, but all dissolved right into the solid solution and also the fortifying, nickel likewise makes the steel eutectoid point to the reduced left, and reduce the eutectoid point of carbon material and stage modification temperature level (A1 and also A2), so compared with various other carbon steel has the exact same carbon content, the variety of ferrite WLDSTEEL reduction as well as refinement, while the pearlite boost.

P 、 S 、 Pt 、 Pb 、 Sb.

These elements are destructive to the reduced temperature strength of steel. They create partition in steel, which lowers the surface energy of grain boundary, lowers the resistance of grain limit, and also creates the weak split to originate from grain limit as well as multiply along grain boundary until the crack is complete.

Phosphorus can improve the stamina of steel yet raise the brittleness of steel, specifically the brittleness at low temperature level. The breakable shift temperature is certainly increased, so the content of phosphorus must be purely restricted.

H, O, N.

These elements will enhance the weak change temperature level of steel. Low temperature durability can be improved by deoxidizing eliminated steels with silicon and light weight aluminum. However silicon raises the weak change temperature level of steel, so aluminum killed steel has a reduced brittle shift temperature level than silicon eliminated steel.

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