What Does the Jominy Calculator Compute?
The calculator estimates hardness in HRC at ten distances from the quenched end of a Jominy bar, from 1.5 mm to 25 mm, using your steel chemistry. You must enter at least carbon and manganese. It plots the curve and lists the values.
What Is the Jominy Hardenability Test?
In the Jominy test, a standard cylinder is heated, then water-quenched at one end only. The quenched end cools fastest and hardens most. Hardness falls with distance from that end. The curve you measure is the hardenability of the steel.
Jominy Calculation Formula and Worked Example
The calculator uses a regression equation for each distance. At 1.5 mm: HRC = 29.27 + 60.38 C + 2.43 Si + 3.14 Mn, with elements in weight %. For C 0.40, Si 0.25 and Mn 0.80: 29.27 + 24.15 + 0.61 + 2.51 = 56.5 HRC. Equations for the later distances add chromium, molybdenum, nickel, copper, phosphorus and nitrogen terms.
How to Read the Result
A slow fall in hardness along the bar means high hardenability: the steel hardens deeper. A fast fall means the steel hardens only near the surface. Alloying elements such as chromium, molybdenum and manganese slow the fall. Carbon sets the hardness at the quenched end.
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Common Questions
What is the Jominy end-quench test?
The Jominy test water-quenches one end of a standard cylindrical steel specimen. We then measure hardness at set distances from that quenched end. The result is a hardness curve that shows how deep the steel hardens.
What is Jominy value and what does it measure?
The Jominy value is the hardness at a given distance from the quenched end. It measures hardenability: how deeply a steel hardens in quenching. Hardenability is different from the maximum hardness a steel can reach, which depends mainly on carbon.
How do you calculate Jominy hardness from chemistry?
OneKaizen's calculator uses one regression equation per distance, with a term for each element. At 1.5 mm it is 29.27 + 60.38 C + 2.43 Si + 3.14 Mn, with each element in weight percent. Later distances add chromium, molybdenum, nickel, copper, phosphorus and nitrogen.
Who uses Jominy hardenability data?
Steel producers, buyers and heat treatment engineers use it to compare steels and to pick a grade that hardens through the section they need.
Is this estimate the same as a Jominy test certificate?
No. A chemistry estimate is not a measured curve, a certificate or an acceptance result. Use a standard end-quench test, such as ASTM A255, when your specification calls for one.
Standard reference: ASTM A255, hardenability test methods.