NM450 weldability
NM450 is a high-strength wear-resistant steel with a hardness of 450 HBW. It has good weldability, allowing welding processes such as welding, MIG welding, gas welding, and shielded metal arc welding. The welding process should be strictly in accordance with the design drawings, parameters and reasonable process requirements.
Since NM450 has high wear resistance and low temperature impact toughness, low crack sensitivity, and good weldability, it is widely used in the manufacturing of corrosion-resistant and wear-resistant components. In particular, the wear-resistant parts of engineering machinery, rock-drilling machinery, nailing machinery, automobiles and other components are all made of wear-resistant steel.
Since the steel contains high hardness elements, such as carbon and manganese, it is difficult to weld and has poor weldability. Its high carbon content can reduce the melting point of the steel, making it prone to cracks, pores, etc. And due to its hardness and toughness, it is difficult to obtain a compact welding slag during welding, which can cause incomplete fusion.
In order to obtain better welding quality, some processing measures should be taken before welding: preheating, electrode selection, pre-plate welding, groove type selection, etc. Preheating can reduce the thermal expansion and contraction during welding, reduce stress concentration and prevent cracking. The choice of welding materials should pay attention to the low manganese content of the welding materials, reduce the probability of cracking caused by austenite formation, and improve the pore and crack resistance of the weld. In addition, it is necessary to pay attention to the appropriate groove type and moderate the groove size, so as to avoid internal stress concentration point.
At the same time, due to the different heat sources and cooling speed, the hardness of the welded part near the weld will be different from that of the raw material, and it is not suitable for parts with high wear resistance stress, so it is necessary to pay attention to the hardness of the welded parts.
After welding, it is necessary to do the corresponding heat treatment, such as stress relief, tempering and so on, so as to obtain better weldability, machinability, dimensional stability and strength. Although the welding of NM450 steel presents many challenges, with prompt processing guidance and the application of appropriate welding techniques, the desired high strength wear-resistant components can be efficiently created.
