Cohen Daugherty posted an update 5 months, 3 weeks ago
Low temperature level steel has outstanding stamina and also durability in reduced temperature setting, excellent welding efficiency, machining performance and also deterioration resistance, are normally specified in the minimum temperature of a certain value of effect strength in the criterion. In reduced temperature steels, elements such as carbon, silicon, phosphorus, sulfur as well as nitrogen degrade the toughness at reduced temperature level, among which phosphorus is taken into consideration to be one of the most dangerous and also must be dephosphorized at reduced temperature in early smelting. Mn, nickel and also various other elements can enhance the toughness at low temperature. With the increase of nickel content by 1%, the critical shift temperature level of brittleness can be reduced by about 20 ℃. Low temperature level strength, i.e. the capacity to avoid brittle failing from happening and also spreading out at reduced temperature levels, is the most important aspect. Today we present the impact of alloying elements on the reduced temperature toughness of steel:
With the boost of carbon material, the breakable change temperature of steel raises rapidly and also the weldability reduces, so the carbon content of low-temperature steel is restricted to less than 0.2%.
The manganese exist in steel with the kind of strong option and also can obviously enhance the durability of steel at reduced temperature level. On top of that, manganese is a component that increases the size of the Austenite region and also minimizes the makeover temperature level (A1 and also A3).
WldSteel is simple to acquire fine as well as ductile ferrite and also pearlite grains, which can make the most of the influence power and also decrease the brittle change temperature. Consequently, the Mn/C ratio need to be at least equal to 3, which can not just minimize the breakable shift temperature level of steel, yet additionally compensate for the reduction in mechanical residential or commercial properties brought on by the reduction in carbon web content due to the boost of Mn.
Nickel can lower the brittleness tendency and also dramatically lower the brittle change temperature level. The impact of nickel on enhancing the reduced temperature toughness of steel is 5 times that of manganese. The brittle change temperature decreases by 10 ℃ with the increase of nickel material by 1%. This is since the nickel does not react with carbon, yet all liquified into the solid option and also the fortifying, nickel also makes the steel eutectoid point to the lower left, as well as decrease the eutectoid point of carbon web content as well as stage change temperature (A1 as well as A2), so compared with various other carbon steel has the very same carbon web content, the variety of ferrite decrease and also improvement, while the pearlite boost.
P 、 S 、 Pt 、 Pb 、 Sb.
These aspects are detrimental to the reduced temperature durability of steel. They create partition in steel, which minimizes the surface area energy of grain limit, minimizes the resistance of grain boundary, as well as creates the fragile fracture to stem from grain boundary and also multiply along grain limit up until the crack is total.
Phosphorus can improve the toughness of steel yet enhance the brittleness of steel, specifically the brittleness at low temperature. The breakable transition temperature is clearly boosted, so the material of phosphorus need to be purely restricted.
H, O, N.
These aspects will raise the weak change temperature level of steel. Low temperature level durability can be enhanced by deoxidizing killed steels with silicon and also light weight aluminum. Yet silicon enhances the brittle transition temperature level of steel, so aluminum killed steel has a lower breakable transition temperature than silicon killed steel.