B93 (В93) Aluminium Alloy: GOST Composition, Tempers & Supply

What is B93 aluminium alloy?

B93 is a heat-treatable, high-strength aluminium alloy registered in GOST 4784, the interstate standard that lists the grades and chemical compositions of wrought aluminium and aluminium alloys used in Russia and the CIS. The high-purity version, В93пч (the suffix "пч" means povyshennoy chistoty, "increased purity"), is the grade that appears in the current composition tables and is what most drawings now call up.

Like 7075, B93 is strengthened by zinc and magnesium, which form fine MgZn₂-type precipitates during artificial ageing, with copper added to raise strength and improve resistance to stress-corrosion cracking. Unlike most Western 7xxx alloys, it contains no chromium or zirconium as a grain-structure control, and its specification sets a minimum iron content rather than only a maximum. These differences give B93 a character of its own: it was developed as a forging alloy that can be quenched with less severe cooling than 7075 while still reaching high strength, which helps limit distortion and residual stress in thick, complex forged parts.

In practice, B93 is specified on Soviet- and Russian-heritage aircraft, helicopter, rocket and heavy-equipment drawings for frames, fittings, brackets and other parts that carry high static and fatigue loads. Buyers outside the CIS usually meet it when they maintain, repair or re-manufacture such equipment, or when a design originates from a Russian or Ukrainian engineering office.

B93 (В93пч) chemical composition, wt %

The limits below are the GOST 4784 values for В93пч. Older documents for plain В93 allow a little more silicon (up to about 0.2 %), so always check which grade and standard edition your drawing quotes. Single values are maximums.

Composition per GOST 4784-97, table for Al-Zn-Mg alloys. A newer edition, GOST 4784-2019, is in force in Russia; confirm the edition named on the purchase order. Density given in the standard: 2.84 g/cm³.

Two things stand out when you compare this analysis with Western alloys. First, the copper level (0.8 – 1.2 %) is lower than in 7075 (1.2 – 2.0 %) and well below 7050 (2.0 – 2.6 %). Second, the absence of chromium and zirconium means grain structure is controlled through processing rather than by dispersoid-forming additions. Both points affect quench sensitivity, toughness and corrosion behaviour, which is why a simple "use 7075 instead" decision is not safe without engineering review.

Heat treatment, tempers and mechanical behaviour

B93 is supplied solution heat-treated, quenched and aged. Its strength in the peak-aged condition is in the same high-strength class as other Al-Zn-Mg-Cu forging alloys, and over-aged tempers trade some of that strength for better resistance to stress-corrosion cracking and exfoliation. Guaranteed values depend on the forging standard, section thickness and test direction (longitudinal, long-transverse or short-transverse), so design values must come from the governing GOST/OST document or the customer specification, and acceptance values from the lot certificate.

The Western tempers are given only to explain intent. They are not formal equivalents, and a Т2 forging cannot be certified as T76 without testing to the Western specification.

GOST and OST documents that cover B93

Russian aluminium standards are split between grade standards, which define chemistry, and product standards, which define dimensions, tempers and guaranteed properties for each form. Aviation parts are often governed by OST 1 industry standards or by the design bureau's own technical conditions (TU). The documents most often seen with B93 are:

If your drawing names only "В93" without a product standard, ask the design authority which document applies before ordering. A certificate that shows only the chemistry against GOST 4784 does not prove that the forging meets the mechanical requirements of the part.

B93 product forms and sizes

Because B93 is a specialised grade, there is no global stock market for it the way there is for 7075 plate. Sizes are agreed for each order. For plate and blanks, weight can be estimated from the GOST density of 2.84 g/cm³: 2.84 kg per square metre per millimetre of thickness.

B93 compared with В95, 7075 and 7050

No widely recognised one-to-one Western equivalent of B93 exists. The nearest alloys by family are 7075, 7050 and the Russian В95; the table compares their registered composition ranges (wt %).

What this means in practice:

7075 is the usual reference when converting a drawing, because its zinc and magnesium levels are close and it is available everywhere. However, 7075 is more quench-sensitive because of its chromium, and its thick forgings in T6 are prone to stress corrosion, so T73 or T7352 is normally specified for forged fittings. 7050 has much better through-thickness properties in heavy sections and is the standard Western choice for thick forgings in T74; it is a sensible candidate where B93 is used for large parts. В95 is the Russian analogue of 7075 and is more common in plate and extrusions than in heavy forgings.

Any substitution on a flight-critical or pressure-bearing part must be approved by the design authority, usually with a review of static strength, fatigue, fracture toughness and stress-corrosion data for the proposed alloy and temper.

Where B93 aluminium is used

• Aircraft structures: frames, fittings, brackets, beams and attachment lugs that carry concentrated loads
• Helicopters: forged hub, gearbox-support and airframe fittings on Russian-heritage designs
• Rocket and space hardware: forged rings, frames and support structures
• Heavy transport: highly stressed forged components where weight saving justifies a 7xxx-type alloy
• Machinery: load-bearing levers, housings and connecting elements re-manufactured to original drawings
• Spares and MRO: replacement parts for equipment designed to GOST material standards

For new designs outside the CIS, engineers usually choose 7050, 7075 or 7175 forgings because the qualification data, supply chain and inspection standards are more accessible. B93 remains important wherever an existing drawing, type certificate or customer contract names it.

Key points for producing and machining B93 forgings

1. Ingot qualityUse homogenised direct-chill cast ingot or billet with controlled hydrogen and inclusion levels; the high-purity В93пч grade limits silicon for better toughness.
2. Forging temperatureForge within the producer's qualified hot-working window and avoid overheating, which can cause incipient melting of zinc- and copper-rich phases.
3. Solution treatment and quenchHeat to the specified solution temperature, then quench promptly. The alloy's lower quench sensitivity allows milder quench media for thick sections, reducing distortion.
4. AgeingAge to Т1 for maximum strength, or to Т2/Т3 where stress-corrosion resistance matters more than peak strength.
5. InspectionCheck grain flow, macro-etch, ultrasonic soundness and mechanical properties in the directions the standard requires.
6. Machining and protectionMachine with sharp carbide tools, allow for stress release in thin walls, and protect finished parts by anodising and priming.

How to order B93 from Metline

1. Share the drawingGrade (В93 or В93пч), product form, temper, the GOST/OST or TU document, sizes, quantity and any test or inspection requirements.
2. Technical reviewWe confirm whether the grade can be supplied to that document or propose a Western alternative (for example 7050-T74 forgings) for your design authority to assess.
3. QuotationPrice, certification and delivery terms (EXW, FOB, CIF or DAP) for your destination.
4. DocumentsMill test certificate to EN 10204 3.1 with chemistry and mechanical results, and third-party inspection on request.
5. Packing and shipmentForgings and blanks are protected against corrosion and packed in seaworthy wooden cases for sea or air freight.

Other GOST alloys and 7xxx forging grades

Related Russian-standard alloys:

Western high-strength alternatives and forging guides:

B93 aluminium (aluminum) alloy: frequently asked questions