Steel spring material is typically hardened to what BHN range?

The hardness of steel springs is a crucial factor in their performance, particularly in applications that require flexibility as well as strength and fatigue resistance. When steel is used for manufacturing springs, it is often alloyed with various elements and subjected to heat treatment to achieve the desired hardness.

The Rockwell hardness scale is commonly used to measure the hardness of materials, including springs, expressed in terms of Brinell Hardness Number (BHN). For steel springs, the typical BHN range is generally considered to fall within the realm of higher carbon content materials, which is reflected in the first option presented.

The range of 0.50 to 0.90% seems to indicate a percentage of carbon content, which is crucial because carbon content directly affects the hardness of the steel. As carbon content increases, so does the possibility of achieving higher hardness levels upon final heat treatment. The range mentioned typically aligns with the specifications for medium to high-carbon steel used in spring applications, hence supporting the validity of this answer.

In contrast, the other ranges presented either do not meet the benchmarks for typical spring steel or may not accurately reflect the industry standards for the composition of steels commonly used in spring applications. Thus, the first answer accurately encapsulates the appropriate range of