What is a Jominy bar?
6.2 Jominy Curves. Jominy bar end-quench test is the most familiar and commonly used procedure for measuring steel hardenability. This test has been standardized and is described in ASTM A 255, SAE J406, DIN 50191, and ISO 642. For this test, a 100 mm (4 in.) long by 25 mm (1 in.)
What do Jominy curves measure?
The Jominy test provides a measure of the ability of a steel to harden by transforming into martensite under set conditions, i.e., a measure of the hardenability of the steel.
What are the types of hardenability?
Hardenability of Steel
- Austenite: Face-Centered cubic iron; also iron and steel alloys that have the FCC crystal structure.
- Ferrite: Body-centered cubic iron and steel alloys that have a BCC crystal structure.
- Cementite: Iron carbide (Fe3C)
How do you calculate Jominy distance?
The resulting curve is called ‘Jominy hardenability curve’ and the distance from the quenched-end is known as Jominy distance-J. (1/16″ = one Jominy distance = J1). Fig. 4.18 illustrates typical Jominy curves of some low alloy steels.
What is Jominy end quench test?
The Jominy end quench test is used to measure the hardenability of a steel, which is a measure of the capacity of the steel to harden in depth under a given set of conditions.
Which ASTM standard governs the Jominy end quench test?
ASTM A 255
12.02. 6.2 Jominy Curves. Jominy bar end-quench test is the most familiar and commonly used procedure for measuring steel hardenability. This test has been standardized and is described in ASTM A 255, SAE J406, DIN 50191, and ISO 642.
What is the difference between water quenching and oil quenching?
Water-quenched steels will generally be harder than oil-quenched steels. This is mainly because the thermal conductivity of water is higher than the thermal conductivity of most oils (that I know); consequently, the rates of cooling will be less rapid (or lower) in oils compared with water.
What is the different alloying elements in the hardness distribution curve during Jominy quench test?
The Jominy end-quench is used to define the hardenability of carbon steels with different alloying elements, such as chromium (Cr), manganese (Mn), or molybdenum (Mo) and having different critical cooling velocities.
How does quenching increase hardness?
Quenching improves a metal’s performance by rapidly cooling the heated metal, thereby altering its molecular structure and increasing its hardness. The rate of quenching may be adjusted to achieve the desired properties.
What is a quenching process?
Quenching involves the rapid cooling of a metal to adjust the mechanical properties of its original state. To perform the quenching process, a metal is heated to a temperature greater than that of normal conditions, typically somewhere above its recrystallization temperature but below its melting temperature.
What is the purpose of quenching?
This powerful, data-rich test method that can ensure that a part is made to specification. The Jominy end quench test [1] [2] (ASTM A255 [3]) is an extremely simple and useful test that is applicable to many materials besides steel [4] [5].
What is The Jominy end-quench test for hardenability?
Introduction to Jominy End-Quench Test for Hardenability of Steels: The Grossman method provides a quantitative measure of the hardenability in terms of ideal diameter. From the practical stand-point, however, this method of quenching a series of rounds is laborious, difficult and expensive.
What is the hardness of Jominy test?
Jominy-end quench test is now widely used for hardenabilities in the range of D I = 1 – 6 inches. For shallow-hardening steels (D I < 1 inch), as the quenched end of Jominy piece is not hardened fully, Grange proposed a hot-brine (H – B) test.
What is Jominy hardenability curve?
The resulting curve is called ‘Jominy hardenability curve’ and the distance from the quenched-end is known as Jominy distance-J. (1/16″ = one Jominy distance = J 1 ). Fig. 4.18 illustrates typical Jominy curves of some low alloy steels.