Core Hardenability Calculations for Carburizing Steels

Effects of Copper on the Hardenability of a Medium-Carbon Steel

“…The initial hardness (i.e., hardness at the first Jominy position) and the 50 pct martensite hardness were calculated from the alloy carbon concentration using expressions provided in ASTM A255-07 [11] and from data and expressions available in Hodge and Orehoski [20] and Tartaglia and Eldis. [14] SAE J406 [13] also provides expressions for these two hardness values, and calculated values using the SAE J406 expressions are approximately 0.3 HRC less than estimates following ASTM A 255-07. [11] The hardness drop between the initial hardness and 50 pct martensite hardness are essentially identical between the two standards.…”

“…9. Tartaglia and Eldis [14] provided regression equations to calculate the base ideal critical diameter, which is a function of carbon concentration, for specific ASTM grain size numbers. Within their framework, the base ideal critical diameter is 12 pct less for a PAGS of ASTM No.…”

“…This point or location can be determined by several methods, which could include metallographic analysis or determining the inflection point of the hardnessdistance curve. In the current study, the absolute hardness method and the hardness drop method advocated by Tartaglia and Eldis [14] were adopted. The initial hardness (i.e., hardness at the first Jominy position) and the 50 pct martensite hardness were calculated from the alloy carbon concentration using expressions provided in ASTM A255-07 [11] and from data and expressions available in Hodge and Orehoski [20] and Tartaglia and Eldis.…”

“…[11][12][13] Multiplying factors are provided by the American Society for Testing Materials (ASTM) International in their ASTM A 255-07 standard, [11] which is based on the original calculation method developed by Grossman. [12] Other standards [13] and methods [14] exist. The SAE J406 [13] standard uses the same multiplying factors as ASTM A 255-07.…”

“…A lower value of the 50 pct martensite hardness would indicate greater hardenability if using the absolute hardness method to determine the ideal critical diameter. Therefore, the ASTM A 255-07 [11] and the Hodge-Orehoski [20] and Tartaglia-Eldis [14] (HOTE) expressions were selected for the present study, because they represent the minimum and maximum critical ideal diameters, respectively, for a given alloy using the absolute hardness method.…”