Where H90 Brass Sits in the Ordinary Brass Family
H90 is a high-copper ordinary brass, nominally 90 percent copper with zinc as the balance. Its behaviour is close to H96, but its slightly lower copper content gives it noticeably higher strength, which makes it a practical compromise where a near-copper material is wanted but a little extra load-carrying capacity is required. Its distinguishing strengths are good mechanical properties, excellent pressure working response and outstanding surface treatment behaviour: H90 accepts electroplating and vitreous enamel readily, which is unusual among the higher-zinc brasses. Typical uses follow directly from that combination, and include decorative and functional parts that must be bright plated after forming.
Chemical Composition Under GB/T 5231
The composition window is tight, as it must be for an alloy whose colour and conductivity depend on copper content.
| Element | Content |
|---|---|
| Copper (Cu), % | 88.0 to 91.0 |
| Zinc (Zn), % | Balance |
| Iron (Fe), % max | 0.10 |
| Lead (Pb), % max | 0.05 |
| Nickel (Ni), % | Up to about 0.5 |
| Total impurities, % max | 0.3 |
Iron and lead are held very low deliberately. Iron raises hardness but damages conductivity and formability, and lead is restricted because H90 is used in potable water and food-adjacent duty and in markets with restricted substance rules. Where the application requires free machining rather than conductivity and surface finish, a leaded free-cutting brass is the appropriate grade instead.
Mechanical Properties by Product Form and Temper
H90 shows a general tensile strength of 390 MPa or more with elongation of at least 3 percent in the hardest common condition, but the delivered values vary widely with form and temper. The following figures describe the usual commercial ranges.
| Product form | Delivery state | Tensile strength | Elongation |
|---|---|---|---|
| Rod, 3 to 40 mm diameter | Y, hard | 330 MPa or more | Low, temper dependent |
| Plate and strip, 0.2 mm and above | M, Y2, Y | 245 to 390 MPa | 3 to 35% |
| Tube | M, M2, Y2, Y | 220 to 360 MPa | 18 to 42% |
| General reference | As supplied | 390 MPa or more | 3% or more |
Hardness follows the same pattern. Tube in the hard condition is normally supplied in the range of about 45 to 105 HV, equivalent to roughly 40 to 100 HB, while annealed material sits at the bottom of those ranges. Because two tempers of the same grade can differ by more than 150 MPa in tensile strength, the delivery condition must always be written on the purchase order.
Product Forms and Size Ranges
Plate and sheet: thickness from about 1 mm to 150 mm.
Rod and bar: diameter from about 4 mm to 350 mm.
Strip: thickness from about 0.1 mm to 3.0 mm, supplied in coil or cut length.
Tube: outer diameter from about 10 mm to 300 mm, with capillary tube available from about 1 mm to 6.1 mm outer diameter.
Wire: diameter from about 0.1 mm to 12.7 mm, in coils or straight lengths.
Forgings: produced to drawing for fittings and valve bodies.
Density is approximately 8.8 g/cm³, which is high among the ordinary brasses and reflects the high copper content. Weight calculation for plate and strip should use the value agreed with the supplier, since a one percent error in assumed density translates directly into a one percent error in invoice weight on a large order.
Applications and Processing Notes
Plating and enamelling: H90 takes nickel, chrome and tin plating, and vitreous enamel, better than most ordinary brasses, which makes it a standard choice for decorative hardware and enamelled badges.
Cartridge case stock: the combination of strength and ductility in the soft and half-hard tempers suits deep drawing of cylindrical shells.
Water supply and drainage: tube and fittings for plumbing lines, with the caveat that long-term wetted service is better served by an inhibited alloy if chlorides are present.
Bimetallic strip and instrument parts: stable thermal expansion combined with good conductivity suits thermostatic and electrical components.
Medals, badges and artworks: colour, polishability and plating response are the governing requirements.
Radiator and heat exchange parts: thermal conductivity and formability in strip form.
Processing practice: anneal in the 520 to 650 degrees Celsius range to restore ductility between cold forming stages, and hot work in the broad range typical of high-copper brasses. Solder and braze with standard fluxes; welding is generally avoided on thin strip because of distortion and heat-affected softening.
FAQ
Q: How does H90 brass differ from H96 brass?
H90 contains 88 to 91 percent copper and H96 contains 95 to 97 percent. H90 is therefore stronger and cheaper, while H96 is closer to pure copper in conductivity, colour and softness.
Q: What is the tensile strength of H90 brass?
Generally 390 MPa or more in the harder common conditions. Rod in the hard state is typically 330 MPa or more, plate and strip range from about 245 to 390 MPa, and tube from about 220 to 360 MPa, depending on temper.
Q: Why is H90 brass chosen for plated and enamelled parts?
Because its high copper content gives excellent surface treatment response. It accepts electroplating and vitreous enamel with good adhesion and a uniform appearance, which lower-copper brasses achieve less reliably.
Q: Is H90 brass suitable for potable water contact?
It is used in water supply and drainage components, but lead content and dezincification risk should be assessed for the specific water chemistry, and an inhibited or lead-free alloy is safer for permanent wetted parts.
Q: What is the density of H90 brass?
Approximately 8.8 g/cm³, high among ordinary brasses because of the roughly 90 percent copper content.
Q: Which delivery states are available?
Soft, half-hard and hard conditions are standard, and the mechanical properties quoted for a grade are only valid for the temper actually supplied.
