How much does carbon content affect the hardness of NM400 wear-resistant steel?

The carbon content has a significant impact on the hardness of NM400 wear-resistant steel.

1、 The principle of increasing carbon content to enhance hardness

Carbon is one of the important elements that affect the hardness of steel. In NM400 wear-resistant steel, as the carbon content increases, its hardness will correspondingly increase. This is mainly because carbon can form various carbides with iron, such as carbides (Fe-C). These carbides have high hardness, and their distribution in steel can effectively hinder the movement of dislocations, thereby improving the hardness and wear resistance of the steel. For example, as the carbon content gradually increases from a lower level, the number of carbides in the steel increases and their distribution becomes more dense, which hinders the movement of dislocations when the steel is subjected to external forces, resulting in a macroscopic increase in hardness.

2、 The negative impact of excessive carbon content

Reduce toughness: Although high carbon content can increase the hardness of NM400 wear-resistant steel, it also increases the brittleness of the steel and reduces toughness. This is because excessive carbides can make the structure of steel harder and more brittle, making it prone to brittle fracture when subjected to external forces such as impact or tension. For example, in some application scenarios that require bearing impact loads, NM400 wear-resistant steel with excessively high carbon content may suddenly fracture, thereby affecting the safety and reliability of the equipment.

Impact on weldability: High carbon content can also have adverse effects on the weldability of NM400 wear-resistant steel. During the welding process, steel with high carbon content is prone to welding cracks and hard and brittle welding heat affected zones. This is because the high temperature during the welding process can cause uneven diffusion of carbon in the steel, resulting in local structural changes and the formation of hard and brittle martensite and other structures, thereby reducing the quality and performance of the welded joint.

Uneven organization: Excessive carbon content may lead to uneven organization of NM400 wear-resistant steel. During the solidification and cooling process of steel, carbon segregation is prone to occur, resulting in high carbon content in certain areas and relatively low carbon content in other areas. This unevenness in organization can affect the stability of steel properties, and may lead to issues such as rapid local wear or insufficient strength during use.

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