Overview
Invar round bar is a specialized nickel-iron alloy containing approximately 36% nickel. Developed in 1896 by Swiss scientist Charles Édouard Guillaume (who won the Nobel Prize for this discovery), Invar exhibits an exceptionally low coefficient of thermal expansion (CTE) at room temperature, typically around 1.2×10⁻⁶/°C between 0-100°C. This unique property makes Invar round bars invaluable in applications where dimensional stability is critical despite temperature fluctuations. The material's name derives from 'invariable,' reflecting its resistance to expansion and contraction. While primarily available as round bars, Invar can also be found in other forms like sheets and wires for different industrial needs.
Physical and Chemical Properties
Invar round bars combine several important physical properties. Their density of 8.1 g/cm³ is slightly lower than pure iron, while maintaining good mechanical strength with tensile strength ranging from 450-550 MPa. The alloy's thermal conductivity is relatively low at about 10 W/(m·K), contributing to its thermal stability. Chemically, Invar demonstrates good corrosion resistance comparable to stainless steels, though prolonged exposure to harsh environments may require protective coatings. The material is non-magnetic at room temperature due to its nickel content, which also enhances its resistance to oxidation. Machinability is fair but requires appropriate tools and cutting speeds to prevent work hardening.
Main Applications
The primary use of Invar round bars is in precision engineering applications where dimensional stability is paramount. They are extensively used in aerospace components such as satellite structures and precision mounts, where temperature variations in space would otherwise cause significant dimensional changes. Other key applications include optical measurement devices, laser components, and scientific instruments like precision pendulums and seismographs. In the energy sector, Invar round bars find use in LNG tank construction due to their stability at cryogenic temperatures. The watchmaking industry also utilizes small diameter Invar rods for precision timekeeping mechanisms.
Safety and Storage
While Invar round bars are generally safe to handle, proper precautions should be taken during machining operations. The generation of metal dust requires adequate ventilation or respiratory protection. The material itself is non-flammable and non-reactive under normal conditions. For storage, Invar round bars should be kept in a dry environment to prevent surface oxidation. While the alloy is corrosion-resistant, prolonged exposure to humid or salty air may lead to surface tarnishing. Stacking should be avoided to prevent surface damage, and protective end caps are recommended for precision-ground bars to maintain dimensional accuracy.
B2B Procurement Guide
When procuring Invar round bars commercially, several factors require attention. First, verify the actual nickel content (should be 35-36%) through material certificates, as this directly affects the thermal expansion properties. Dimensional tolerances are crucial - precision-ground bars typically offer tolerances of ±0.02mm. Lead times can be significant for specialty sizes, so plan procurement accordingly. Reputable suppliers should provide mill test reports and may offer additional services like precision cutting or machining. Consider ordering samples for critical applications to verify material properties before large-scale procurement. For reference, standard diameters range from 5mm to 150mm, with custom sizes available from some manufacturers.
Related Manufacturers
- 主营：高温合金、哈氏合金、蒙耐尔合金、Inconel 718、Hastelloy C276、Monel400、Inconel X750、Inconel625、Incoloy 825、Haynes188、Haynes 25、GH3030、GH5188、GH3625、GH3536、GH2132、GH3044、GH4145、GH3600、GH3039、Alloy 20、Alloy28、GH4169圆钢、精密合金
- 主营：Q355C钢板、Q355D钢板、Q355ND钢板、Q355NE钢板、Q460C高强板、Q550D高强板、Q690D高强板、Q245R容器板、Q345R容器板、Q345qD桥梁板、NM400耐磨板、NM500耐磨板、耐候钢板、耐酸钢板、Q355CH型钢、Q355DH型钢、Q235CH型钢、Q355C槽钢、Q355D槽钢、Q355C角钢、Q355D角钢、Q355C工字钢、Q355D工字钢、Q355C圆钢、Q355D圆钢
- 主营：高弹性合金、弹性合金板材
- 主营：精密带、输送带、镀镍带、缠绕垫、合金线、合金带、镜面板、抛光带、平垫圈、弹簧带、输送机、不锈钢板、环形钢带、复合垫片、合金钢管、不锈钢垫、拉丝钻孔、电池镍带、钢带定制、五金垫片、法兰垫片、线材钢带、石墨垫片、不锈钢带、开口垫片
- 主营：航空专用合金、高温合金、钴基合金、马氏体时效钢、GH5188、GH3625、GH4169、L605、1J22钴基合金、GH4099、叶片钢、4J29可伐合金、PH13-8Mo、Aermet100、GH5605、1J22、18Ni300、18Ni350、Monel400、MP159、MP35N、3J21、GH2747、18Ni250
- 主营：钨合金、钼合金、高温合金、高比重合金、钨镍铁、钨镍铜、TC4钛合金、ta2纯钛棒、AZ31镁合金、镁合金az91d、镍钛合金、银钨合金、钨铜合金、司太立、钴铬钼、金属镓、镓铟锡合金、镍基合金、TZM钼合金、巴氏合金、稀有金属、可伐合金、铝中间合金、低熔点合金、钨铼丝
- 主营：镍基合金、哈氏合金、膨胀合金、高温合金、英科洛伊、软磁合金、精密合金、马氏体时效钢、纯镍合金、不锈钢材料
- 主营：殷钢4j36多少钱一公斤、高温合金
- 主营：高温合金、哈氏合金、蒙乃尔合金、钛合金、钴基合金、马氏体时效钢、双相不锈钢、沉淀硬化钢、尼莫尼克合金、司太立合金、软磁合金
- 主营：高温镍基合金、哈市合金、蒙乃尔合金
- 主营：4J36圆棒、高温镍基合金
- 主营：马氏体时效钢、哈氏合金、纯镍合金、329圆棒、圆棒材、光圆棒、400圆棒、718圆棒、钛合金、不锈钢丝、黑皮板、轧板材、718锻板、合金丝、研磨棒、光亮棒、电渣料、无缝管、718圆钢、双相钢、合金板、630棒材、318圆钢、440锻棒
- 主营：模具钢、合金钢、高速钢、优特钢、锰钢、镁合金、钛材、铜材、不锈钢、铝合金、高速粉末钢、透气钢
- 主营：钛合金板、钛板、钛棒、纯钛板、TC4钛合金、4j36、4j32、4j29、镍基合金、钛合金、高温合金、钛管、钛丝、钛线、TA1、TA2、TC4、TC4钛板、可伐合金、软磁合金、铁镍合金、GH4169、N6纯镍、N4纯镍、哈氏合金
- 主营：不锈钢、合金钢管、镍基合金、高温合金、合金钢板
- 主营：马氏体时效钢、高温镍基合金、哈氏合金、4J36圆棒、精密合金、水电钢、钛合金、双电渣、耐蚀板、钛光板、镜面板、锻圆钢、车光棒、255合金、冷轧板、合金棒、抗拉棒、剥皮棒、磁合金、镍合金、416圆钢、时效板、18Ni300、18Ni250、拉光棒
- 主营：模具钢、高速钢、粉末高速钢、4j36圆棒、优特钢、锰钢、镁合金、钛材、铜材、铝合金、不锈钢、透气钢