Maloney Daugherty posted an update 1 month, 1 week ago
Low temperature steel has exceptional toughness and toughness in reduced temperature environment, good welding performance, machining performance as well as corrosion resistance, are typically defined in the minimum temperature of a specific value of effect sturdiness in the standard. In reduced temperature level steels, elements such as carbon, silicon, phosphorus, sulfur as well as nitrogen degrade the durability at reduced temperature level, amongst which phosphorus is considered to be one of the most hazardous and ought to be dephosphorized at reduced temperature level in early smelting. Mn, nickel and also various other aspects can improve the durability at low temperature. With the boost of nickel material by 1%, the vital transition temperature level of brittleness can be reduced by about 20 ℃. Low temperature strength, i.e. the capacity to avoid weak failing from taking place and also spreading out at low temperatures, is the most vital variable. Today we introduce the influence of alloying components on the low temperature level strength of steel:
With the boost of carbon content, the weak change temperature of steel increases quickly and also the weldability lowers, so the carbon web content of low-temperature steel is limited to much less than 0.2%.
The manganese exist in steel with the type of strong option and can certainly improve the strength of steel at low temperature. Additionally, manganese is an element that expands the Austenite region as well as decreases the transformation temperature level (A1 and A3). It is simple to acquire fine as well as ductile ferrite as well as pearlite grains, which can maximize the effect energy as well as minimize the brittle change temperature. Because of this, the Mn/C ratio must be at least equal to 3, which can not just reduce the brittle transition temperature level of steel, but likewise compensate for the decline in mechanical buildings triggered by the decrease in carbon material due to the boost of Mn.
Nickel can lower the brittleness propensity and dramatically lower the weak change temperature. The impact of nickel on improving the reduced temperature level toughness of steel is 5 times that of manganese. The fragile change temperature reduces by 10 ℃ with the boost of nickel material by 1%.
wldsteel is because the nickel does not react with carbon, however all dissolved into the strong solution as well as the conditioning, nickel also makes the steel eutectoid indicate the reduced left, and also lower the eutectoid point of carbon content as well as phase change temperature (A1 and A2), so compared with various other carbon steel has the same carbon material, the number of ferrite reduction as well as improvement, while the pearlite rise.
P 、 S 、 Pt 、 Pb 、 Sb.
These aspects are harmful to the low temperature strength of steel. They generate segregation in steel, which minimizes the surface power of grain border, decreases the resistance of grain boundary, and also triggers the weak fracture to stem from grain border and also proliferate along grain limit until the fracture is full.
Phosphorus can improve the toughness of steel but increase the brittleness of steel, specifically the brittleness at low temperature. The brittle change temperature is certainly boosted, so the web content of phosphorus need to be strictly restricted.
H, O, N.
These components will certainly enhance the weak shift temperature of steel. Reduced temperature durability can be improved by deoxidizing killed steels with silicon and light weight aluminum. However silicon increases the weak transition temperature level of steel, so light weight aluminum eliminated steel has a lower fragile change temperature level than silicon killed steel.