ASTM B777 Class 2 Tungsten Heavy Alloy
Elmet Technologies ASTM B777 Class 2 Tungsten Heavy Alloy (WHA) specification overview. This guide will help you understand the properties, benefits, materials, and the common sizes of WHA Class 2 Elmet manufactures. Here at Elmet Technologies, we want to provide our clients with in-depth specifications of ASTM B777 Class 2 WHA.
Overview
What is ASTM B777 Class 2 tungsten heavy alloy? Is all tungsten metal the same? These are questions we often hear from customers researching tungsten metals for industrial applications. Pure Tungsten, also known as Wolfram, is an element that was first discovered in 1781. Tungsten is represented on the periodic table with symbol W and atomic number 74. Pure tungsten (W) is not the same thing as what is commonly referred to as tungsten alloys, tungsten heavy alloys or WHA. According to ASTM B777, there are four (4) classes of tungsten heavy alloy, namely class 1, class 2, class 3, and class 4. In this section, we’ll discuss ASTM B777, Class 2.
ASTM B777 Class 2 Properties
Class 2 WHA material contains nominally, 92.5 weight percent (wt.%) Tungsten (W). Elmet’s Class 2 products are designated as ET92.5 and ET92.5NM. ASTM B777 WHA, Class 2 provides a nice balance between density, strength and machinability so it is often used in medical shielding applications and KEP defense applications. Class 2 material starts out as a blended metal powder (Pure W mixed with a binder of Ni and Iron). Then, it is pressed and sintered. In some cases, it is machined into high quality tungsten heavy alloy (WHA) blocks, rods, and shaped parts. Class 2 has a lower density when compared to Pure Tungsten or Class 3, & 4. However, it still offers over twice the density of steels and most nickel-based super alloys.
Elmet: Class 2 WHA Capabilities
Elmet can also further “work” Class 2 WHA material through our unique processes such as high temperature rod swaging or hot plate rolling. Consequently, this enables us to make longer pieces and further increase yield strength. Class 2 elongation can be further improved (additional fraction resistance) by specialized post-sintering heat treatment.
All of Elmet’s Class 2 ET92.5 material is made in the USA at our fully integrated facility in Lewiston, Maine.
ASTM B777 CLASS 2: SPECIFICATIONS & TECHNICAL DATA
The below table highlights the properties of the Class 2 tungsten alloys (for both low mag and non mag). This includes mechanical properties. The ASTM B777, AMS 7725, and legacy AMS and MIL-T-21014 Class 2 nominal compositions and properties are as follows:
GRADE | ET92.5 | ET92.5NM |
ASTM B-777 | Class 2 | Class 2 |
AMS 7725E | Class 2 Type 2 | Class 2 Type 1 |
MIL-T-21014D | Class 2 | Class 2 |
W content, wt.% | 92.5 | 92.5 |
Ni content, wt.% | 5.3 | 6.7 |
Fe content, wt.% | 2.2 | 0.8 |
Density, g/cm3 | 17.5 | 17.5 |
UTS, ksi | ≥ 110 | ≥ 110 |
UTS, MPa | ≥ 758 | ≥ 758 |
YS, ksi | ≥ 75 | ≥ 75 |
YS, MPa | ≥ 648 | ≥ 648 |
Elongation, % | ≥ 5 | ≥ 5 |
Hardness, HRC | ≤ 33 | ≤ 33 |
| Mag. perm. | > 1.05 | ≤ 1.05 |
Sizes of WHA Class 2 Material
Elmet stocks a large quantity of its Class 2 blended powder in order to provide rapid turn around for pressing and sintering the specific size a customer needs. Elmet has a large and growing inventory of standard mold sizes which further help with shorter lead-times (or special tooling can be made for matching the exact size needed for a project). All sizes can be sold “rough as sintered” or machined to provide tighter tolerances. As mentioned above, sintered WHA blanks can also be further rolled or swaged by Elmet to produce larger plates, sheets, and rods. Elmet also precision machines WHA parts for use as ballast weights, radiation shields, boring bars, ordnance components, and other components that require high density and good ductility.
Benefits of WHA Material
Class 2 WHA (ET92.5) is the balanced generalist alloy of the 4 classes – with a wide appeal given its blend of density, stiffness, and toughness. ASTM B777 Class 2 WHA provides excellent damage resistance with strong radiation attenuation so it is often used for downhole applications where shielding components from disruption from Earth’s magnetic fields is critical. Also, Class 2 tungsten heavy alloy is often used for kinetic energy penetrators, fragmentation spheres and cubes, aerospace balance weights, medical shielding and other applications that require high density material.
The benefits and advantages of WHA material include:
- Environmental and density advantages over lead for radiation shielding
- Unique capabilities for vibration dampening and balance weight applications
- Ideal for applications requiring very high density
- Often leveraged in defense applications for its unique combination of YS, elongation and density
- Excellent ability to absorb gamma rays and x-rays
- Comparatively, it has improved machinability as compared to Class 3, 4 and pure tungsten
Elmet Technologies: Your Edge in Performance Metals
Elmet brings innovation, engineering, technical support, logistics, and production resources to our customers. We are committed to meeting our customer’s needs, and because of our long history in the industry, we have the knowledge and experience to do so. Our refractory metals expertise covers a wide array of pure metals (W and Mo) and alloys (TZM, MoLa, MoTa, WHA, WK, HCT) and serves a wide range of industries. The defense, lighting, electronics, semiconductor, thin-film, automotive, aircraft, and medical industries all use refractory metal products from Elmet Technologies.
To discuss your ASTM B777 Class 2 Tungsten Heavy Alloy (WHA) requirements, or to inquire about our product capabilities, please contact us at [email protected]