If you work in the aerospace, marine, chemical, or oil and gas industries, you've likely encountered Inconel 625, a nickel-chromium-molybdenum alloy known for its exceptional corrosion resistance, high-temperature stability, and mechanical strength. One question we frequently receive from customers is: "What is the hardness of Inconel 625?"
In this guide, we will detail the hardness values of Inconel 625, the factors that influence its hardness, how to accurately test its hardness, and why this characteristic is crucial for your specific application.
Why Hardness Matters for Your Project?
Machinability: Harder material can increase tool wear and machining cost. Understanding the hardness helps select the right cutting tools and parameters.
Wear Resistance: Components subjected to friction or impact benefit from higher hardness.
Structural Integrity: Ensures that components maintain mechanical strength under high stress, high temperature, or corrosive environments.
Inconel 625 Hardness
Inconel 625 is a nickel-chromium-molybdenum alloy strengthened primarily by solid solution rather than precipitation hardening. Its hardness varies slightly depending on the form (plate, sheet, bar, or pipe) and heat treatment, but typical values are as follows:
| Form / Condition | Hardness (HRB / HRC / HV) |
|---|---|
| Annealed / As-Fabricated | 95–100 HRB (~20 HRC, 200–220 HV) |
| Cold Worked / Work Hardened | 25–35 HRC (~250–350 HV) |
| Solution Treated | 22–28 HRC (~230–280 HV) |
What is the minimum hardness of Inconel 625?
The minimum hardness for annealed Inconel 625 is typically 190 HBW (200 HV or 85 HRB), per ASTM B446 standards.
What is the density of Inconel 625?
The density of Inconel 625 is typically listed as 8.44 g/cm³ (grams per cubic centimeter) or 0.305 lb/in³ (pounds per cubic inch), which is a key physical property of this high-performance nickel-chromium alloy.
Factors That Affect Inconel 625's Hardness
Understanding what impacts Inconel 625's hardness helps you select the right material condition and avoid performance issues. Here are the top 3 factors:
Inconel 625 Heat Treatment Process
Inconel 625 is typically supplied in the annealed condition (heated to 1100–1150°C, then cooled rapidly), which optimizes ductility and corrosion resistance while maintaining moderate hardness. For applications requiring higher hardness (e.g., wear-resistant components), precipitation hardening (aging at 700–800°C for 2–8 hours) increases hardness by forming intermetallic phases (γ" and γ'), without sacrificing too much corrosion resistance.
Inconel 625 Cold Working
Cold working (such as rolling, drawing, and bending) increases the hardness of Inconel 625 alloy by introducing dislocations into the metal structure. For example, cold-worked Inconel 625 tubing can achieve a hardness of 250-280 HV, making it ideal for high-pressure applications.
Impurity Content
Inconel 625's chemical composition is tightly controlled (Ni: 58% min, Cr: 20–23%, Mo: 8–10%, Nb+Ta: 3.15–4.15%). Trace impurities (e.g., carbon, sulfur) can slightly alter hardness-for instance, higher carbon content may increase hardness but reduce weldability. Always choose suppliers that adhere to ASTM or ASME standards for composition control.
Can Inconel 625 be hardened further?
Yes,heat treatment (precipitation hardening) or cold working can increase its hardness. However, excessive hardening may reduce ductility and corrosion resistance.
Inconel 625 harder than 316 stainless steel?
Yes. Annealed Inconel 625 (190–220 HBW) is harder than annealed 316 stainless steel (150–180 HBW), thanks to its higher nickel, molybdenum, and niobium content.
If you have project requirements for Inconel 625 stainless steel bars, we welcome your order. GNEE has a large inventory of popular products for you to choose from. It can be processed into various practical product forms, including plates, coils, tubes, bars, and wires. For detailed chemical composition information and free samples, please contact our factory immediately. We offer competitive prices and excellent service.
