UNS R30783 forgings

UNS R30783 is a low-thermal-expansion, oxidation-resistant cobalt-nickel-iron superalloy strengthened by beta-NiAl and gamma prime precipitates. It contains roughly 34 % cobalt, 26 to 30 % nickel, 24 to 27 % iron, 5 to 6 % aluminium and 2.5 to 3.5 % each of chromium and niobium. It is used for gas turbine seal rings, shrouds and casing components. Jiangyin Jiangnan Metal Co., Ltd. in Jiangyin, Jiangsu, China supplies it as open-die forgings.

UNS R30783 is most often called Alloy 783. It is also written as alloy 783, Inconel alloy 783, or simply 783. All of these refer to the same low-expansion Co-Ni-Fe superalloy covered by UNS designation R30783.

UNS R30783 contains 26.0 to 30.0 % nickel, 24.0 to 27.0 % iron, 5.0 to 6.0 % aluminium, 2.5 to 3.5 % chromium, 2.5 to 3.5 % niobium, 0.10 to 0.40 % titanium and 0.003 to 0.012 % boron, with cobalt as the balance at approximately 34 %. Copper, manganese and silicon are each limited to 0.50 % maximum, carbon to 0.030 %, phosphorus to 0.015 % and sulfur to 0.005 %.

Chromium is held to 2.5 to 3.5 % in UNS R30783 because chromium is the element that raises thermal expansion in superalloys. Oxidation resistance comes instead from 5 to 6 % aluminium, which forms a beta-NiAl phase and an adherent alumina scale. That substitution gives the alloy a coefficient of 10.08 µm/m·°C at 93 °C, about 22 % below Alloy 718, while it still survives in hot air.

At room temperature in the solution-treated and double-aged condition, UNS R30783 has a tensile strength of 1194 MPa (171 ksi), a 0.2 % yield strength of 779 MPa (113 ksi), 24 % elongation at break, an elastic modulus of 177.3 GPa and a Poisson's ratio of 0.31. Its density is 7.81 g/cm³ and it melts between 1336 °C and 1407 °C.

UNS R30783 is used for gas turbine seal rings, shroud supports, turbine and compressor casings, combustor and transition-piece hardware, compressor stator parts, aero-engine static structure and steam turbine valve spindles. It is chosen when a hot component has to hold a tight running clearance, because it expands less than conventional superalloys while resisting oxidation in air.

UNS R30783 expands about 22 % less than Alloy 718 and gets its oxidation resistance from an aluminium-formed alumina scale rather than from chromium. Alloy 718 is the stronger of the two in the aged condition. Choose UNS R30783 when dimensional stability and clearance control at temperature matter more than peak strength, and Alloy 718 when strength governs. Incoloy 909 is the other low-expansion option, but its oxidation resistance in air is markedly poorer.

UNS R30783 is available as seamless rolled rings up to 3000 mm outside diameter, round bar from 20 to 800 mm diameter, flat and square bar, discs and blanks up to 1500 mm diameter, blocks and plates, hollow bars, sleeves and bushings, casings, shells, cylinders and housings, shafts, spindles and valve stems, impeller wheels and turbine discs, and turbine seal rings and shroud segments to drawing. Jiangyin Jiangnan Metal Co., Ltd. open-die forges all of these to order.

Jiangyin Jiangnan Metal Co., Ltd. supplies UNS R30783 (Alloy 783) forgings from its open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China. Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659. The company forges the grade into rings, bars, discs, sleeves, casings and turbine components, and ships worldwide with EN 10204 3.1 certification.

Every UNS R30783 forging ships with an EN 10204 3.1 mill test certificate showing heat number, full chemical analysis and mechanical test results. Standard testing covers chemistry to ASTM E1473, tensile to ASTM E8/E8M and ASTM E21, grain size to ASTM E112, ultrasonic inspection to ASTM E2375 and liquid penetrant to ASTM E1417. Third-party witness inspection by an agency such as SGS, BV or TUV can be arranged on request.

Send the drawing or the dimensions, quantity, delivery condition and any specification you need to sales@steelforgepieces.com, and Jiangyin Jiangnan Metal Co., Ltd. will come back with a quotation. Price for UNS R30783 depends on piece weight, size, quantity, machining allowance and heat-treat condition, so there is no list price. Single-piece and prototype quantities are accepted.