Materials used
Below is an overview of materials used in anchoring elements. They differ in resistance to temperature, corrosion, sulphuric environment and other properties. We use these alloys to manufacture our anchoring systems and we also sell them as raw material.
We will be happy to assist you in selecting the suitable alloy for your application. We can also supply other types of materials.
Quick material selection: AISI 304 ¦ AISI 309 ¦ AISI 310S ¦ AISI 310 ¦ AISI 330 ¦ DS ¦ 253 MA ¦ Inconel 601
AISI 304 (1.4301)
AISI304 is the most common alloy used in stainless steel anchors. It is a general purpose alloy suited for a variety of corrosion resistant applications. It offers excellent high temperature resistance, up to 750 °C. In temperatures over this limit, oxidation and corrosion resistance is drastically reduced. It is susceptible to several hardening/embrittlement phenomena, including 'Sigma' and heavy carbide precipitation in the grain boundaries when exposed to temperatures around 650 °C for a long period of time. We recommend AISI 304 for use in applications involving constant temperatures of up to 750 °C (significant thermal cycling may cause embrittlement).
AISI 309 (1.4828)
The AISI 309 alloy has a characteristically low nickel content and a relatively high chrome content. The low nickel content means that this alloy can still be used effectively in environments where sulphur is present. It has good stability and is suitable for use in temperatures of up to 1,000 °C. Its composition makes it susceptible to embrittlement as a result of Sigma phase development, which makes it unsuitable for applications involving thermal cycling. We recommend AISI 309 for applications involving constant high temperatures.
AISI 310S (1.4845)
This is a very popular alloy type in our industry, with good strength and oxidation resistance. Even though it is susceptible to Sigma precipitation, it is resistant to thermal cycling and oxide spalling damage, especially in environments with high gas velocity. The higher the application temperature the lower the oxidised layer's resistance, with 1,100 °C being the critical temperature. This alloy has a moderate sulphur resistance, owing primarily to its higher nickel content. Other factors influencing its resistance include carburisation or a possible carbon build-up. With CUPLOCK, anchors made of this alloy may be used in temperatures of up to 1,200 °C and are especially suitable for gas kilns.
AISI 310 (1.4841)
This alloy has the same properties and specifications as AISI 310S, but a higher carbon content (max. 0.25). This alloy steel is frequently used as a standard anchor material for applications involving high temperatures. It offers good thermal and anti-corrosive properties and may be used in temperatures of up to 1,150 °C. Similarly to AISI 309, AISI 310 is also very susceptible to sigma phase embrittlement and should therefore be used primarily for constant temperature applications.
AISI 330 (1.4864)
This alloy is able to withstand temperatures up to 1,250 °C in oxidising environments. It has good oxide adhesion, resistance to spalling, and is totally immune to SIGMA formation. It is especially suitable for metal annealing furnaces, where thermal cycling occurs. It has good strength and thermal shock resistance. This alloy is not suitable for applications where sulphur is present as a result of its high nickel content. It is however well suited for oxygen depleted environments. It has good carbon and nitrogen absorption resistance and is a good alternative to Inconel 601, especially for heavy refractory anchors. With lock washer applications this alloy is equal to or superior to Inconel 601 due to its higher melting point (1400 C).
DS (1.4862)
The DS is similar to AISI 330 and is suitable for anchoring systems that are to be used at high temperatures, especially under strongly carburised or nitrating conditions. With good stability values, this alloy is completely immune against formation of sigma phases as a result of its composition, so it can also be used in systems that are operated in cycles. The DS alloy is often used as a replacement for AISI 330, because it is readily available on the market.
253 MA (1.4835, 1.4893)
This steel is based on the 309 alloy, with small additions of rare earth elements, which give it excellent oxidation resistance in temperatures of up to 1,150 C°. Due to the low nickel content in the alloy, there is a good resistance against SO2 and SO3. An oxygen depleted atmospheres will corrode this alloy severely by rapid removal of the oxide scale. H2S in very small quantities will attack the oxide scale. It offers great strength in high temperatures as a result of solid solution particles formed by the rare earth element additions. It is however slightly susceptible to Sigma formation and is therefore not suitable for use in severe thermal cycling applications, as cycling may cause the anchors to break after having been in use for long periods of time. This alloy is ideally suited for continuous high temperature applications demanding slightly better performance than type 310 AISI.
Inconel 601
This alloy excels in high temperatures and is especially suited for applications above 1,100 °C. It may be used in up to 1,250 °C, although its melting point is close to 1,300 °C. This alloy offers superior strength right up to the melting point. It is immune to SIGMA formation and great for thermal cycling and thermal shock applications. It has excellent oxide scale adhesion to the base metal due to the addition of aluminium. It is however not suited for environments with gasses containing traces of sulphur or vanadium oxides, due to its high nickel content. It tends to undergo eutectic transformation at approximately 650 °C, which weakens the base metal structure significantly. For ceramic fibre refractory, it should be used in combination with 330 AISI lock washers or ceramic cuplocks. Inconel 601 has superior strength compared to other alloys and should therefore be used for heavier refractory in temperatures above 1,150 °C. Inconel 601 may be prone to internal oxidation when the stresses on the anchor exceed 5 - 10% of creep rate within 10.000 hrs. In such cases, more anchors per square meter should be applied.