Reduced temperature level steel has superb toughness and strength in low temperature atmosphere, excellent welding efficiency, machining performance and deterioration resistance, are typically specified in the minimum temperature of a particular worth of influence strength in the requirement. In reduced temperature steels, aspects such as carbon, silicon, phosphorus, sulfur as well as nitrogen degrade the toughness at reduced temperature, amongst which phosphorus is thought about to be one of the most dangerous and also ought to be dephosphorized at reduced temperature in early smelting. Mn, nickel and also other aspects can improve the toughness at low temperature level. With the rise of nickel web content by 1%, the critical transition temperature of brittleness can be reduced by about 20 ℃. Low temperature strength, i.e. the ability to avoid brittle failing from happening and spreading out at reduced temperatures, is the most essential element. Today we present the influence of alloying aspects on the low temperature toughness of steel:
C.
With the boost of carbon content, the fragile change temperature level of steel boosts quickly and also the weldability decreases, so the carbon material of low-temperature steel is limited to much less than 0.2%.
Mn.
The manganese exist in steel with the form of solid service as well as can certainly improve the toughness of steel at low temperature. In addition, manganese is an aspect that expands the Austenite area and decreases the change temperature level (A1 and also A3). It is very easy to get great and pliable ferrite and pearlite grains, which can make best use of the impact power as well as decrease the breakable transition temperature. Because of this, the Mn/C proportion should be at least equal to 3, which can not just decrease the weak change temperature level of steel, but likewise make up for the decline in mechanical residential properties caused by the decrease in carbon content due to the rise of Mn.
Ni.
Nickel can decrease the brittleness propensity and also considerably decrease the breakable transition temperature. The impact of nickel on improving the reduced temperature strength of steel is 5 times that of manganese. The brittle shift temperature reduces by 10 ℃ with the increase of nickel web content by 1%. This is because the nickel does not react with carbon, but all dissolved into the strong option and the conditioning, nickel also makes the steel eutectoid point to the lower left, as well as lower the eutectoid point of carbon material and also phase modification temperature level (A1 as well as A2), so compared to other carbon steel has the same carbon web content, the number of ferrite reduction and improvement, while the pearlite boost.
P 、 S 、 Pt 、 Pb 、 Sb.
These aspects are damaging to the reduced temperature sturdiness of steel. They create partition in steel, which minimizes the surface area power of grain limit, minimizes the resistance of grain limit, and causes the weak crack to originate from grain boundary and also proliferate along grain boundary till the fracture is complete.
Phosphorus can WLDSTEEL enhance the stamina of steel yet enhance the brittleness of steel, especially the brittleness at reduced temperature level. The breakable change temperature level is undoubtedly enhanced, so the content of phosphorus need to be purely limited.
H, O, N.
These elements will raise the breakable change temperature of steel. Reduced temperature level sturdiness can be improved by deoxidizing eliminated steels with silicon and light weight aluminum. Yet silicon boosts the weak shift temperature of steel, so light weight aluminum killed steel has a lower fragile shift temperature level than silicon eliminated steel.