As Musk fully shifted to using 300 series (mainly Type 301) stainless steel as the main structural material for Starship and Super Heavy boosters from the end of 2018 to the beginning of 2019, the plan to build rockets with stainless steel began to be hotly discussed. The first thing Musk talked about was switching to 301 stainless steel because 301 stainless steel is very corrosion-resistant and cheaper than the carbon fiber used in other rocket manufacturing. Then on March 14, 2020, Musk responded to others on Twitter that 304L stainless steel would be used for some parts because it has higher toughness at low temperatures. To date, the starship has flown nine times, and some domestic companies have begun to try to use stainless steel materials to develop rockets. Let\u2019s talk about some things about stainless steel rockets.<\/p>\n
1. The reason why Musk chose to use stainless steel to build rockets<\/p>\n
The reasons given by Musk are as follows: First, the most intuitive reason is that it is cheap, and using stainless steel can significantly reduce costs. Compared with commonly used carbon fiber composite materials and aluminum alloy materials, stainless steel is obviously much cheaper. According to Musk, without considering the processing technology and only considering the material cost, if carbon fiber composite materials are used to build a rocket, the cost per kilogram will exceed US$135. If 35% loss is added, the cost per kilogram will reach US$200. The same rocket made of 301 stainless steel sheets costs about US$3 per kilogram.<\/p>\n
In addition to cost, there are also performance considerations. When the “Starship” re-entered the atmosphere, 20% of the surface was exposed to a high temperature of about 1470\u00b0C, and the highest temperature of the remaining 20% \u200b\u200bof the surface was about 1300\u00b0C. The melting point of stainless steel is 1398-1454\u00b0C, which is more resistant to high temperatures than other current mainstream rocket materials. Although carbon fiber will not melt, the resin will be destroyed at a certain temperature. In comparison, carbon fiber is still not good at resisting high temperatures. In addition, the strength of stainless steel will increase by 50% at low temperatures, even higher than that of aluminum-lithium alloys. Stainless steel added with chromium and nickel will also increase ductility by 12-18%, making it stronger than carbon fiber.<\/p>\n
2. Which domestic companies are trying to use stainless steel to build rockets?<\/p>\n
1.Beijing Jianyuan Technology Co., Ltd.<\/p>\n
Jianyuan Technology was established in 2019 and is the first private rocket company in China to adopt the “stainless steel rocket body + liquid oxygen methane power” solution. The core product of Jianyuan Technology is Yuanxingzhe 1, with a rocket body diameter of 4.2 meters. In January 2023, Arrowyuan Technology successfully conducted three full-scale stainless steel rocket XZH-1 first-stage static ignition tests at the Bengbu test base in Anhui Province, marking a major breakthrough in the application of stainless steel materials in rocket engineering.<\/p>\n
2. Blue Arrow Aerospace Technology Co., Ltd.<\/p>\n
Blue Arrow Aerospace was established in 2015. On December 9, 2023, Blue Arrow Aerospace announced its own stainless steel rocket plan. The specific model is Zhuque 3. The diameter of the rocket body is 4.5 meters. The rocket tank is made of S301 series stainless steel.<\/p>\n
3.Beijing Yushi Space Aerospace Technology Co., Ltd.<\/p>\n
Founded in 2024, Yushi Space is a newly entered private rocket company. It is also the only private rocket company in China that claims to adopt the “stainless steel rocket body + chopstick capture arm recovery” solution. Yushi Space’s core product is the AS-1 rocket, with a rocket body diameter of 4.2 meters.<\/p>\n
4.Lightyear Exploration (Jiangsu) Space Technology Co., Ltd.<\/p>\n
Lightyear Exploration was founded in 2022. The founder Wang Lipeng used to work in the First Department of Aerospace Science and Technology. It uses stainless steel bulging tank technology and cold work hardening process to tensile and strengthen ordinary stainless steel (such as 230 MPa) to 712.5 MPa to achieve a high-strength thin-walled structure (wall thickness as low as 1.5 mm). In 2024, Lightyear Exploration successfully developed a stainless steel storage tank with a diameter of 3.8 meters. The total length of the storage box is 14.6 meters, the volume is 158m\u00b3, the minimum wall thickness is 1.52mm, the design load at the bottom of the box is 0.75MPa, and the whole box mass is 3400kg. In 2025, Lightyear Exploration successfully completed the manufacturing of a stainless steel bulging ellipsoid box bottom with a diameter of 3.35 meters, marking that the stainless steel bulging tank technology independently developed by Lightyear Exploration has officially completed engineering verification and entered the mass production stage.<\/p>\n
5. Universal Aerospace (Qingdao)<\/p>\n
In 2024, Universal Aerospace (Qingdao) established a core team composed of experts in materials science, sheet metal, riveting, spinning, welding and other fields, and successfully overcame key technical problems such as sheet metal forming technology of stainless steel materials for complex parts (cold work hardened high-strength stainless steel), high-precision assembly and welding technology, and orthopedic stress relief treatment of welds. In February 2025, Universal Aerospace successfully completed the development of the first 4.2-meter-diameter thin-walled stainless steel rocket storage tank.<\/p>\n
3. Disadvantages of making rockets out of stainless steel<\/p>\n
The density of stainless steel (approximately 7.8 g\/cm\u00b3) is much higher than that of carbon fiber (approximately 1.6 g\/cm\u00b3) and aluminum-lithium alloy (approximately 2.6 g\/cm\u00b3), which directly increases the dry weight of the rocket body. If the rocket body is too heavy, it will compress the payload and carry less fuel and cargo. Therefore, to use stainless steel to build rockets, the engine must be excellent enough. Musk uses stainless steel to build rockets, including Musk’s choice to return to the site for recycling. The main reason is that the starship is equipped with a Raptor engine. The thrust of Raptor 2 at sea level reaches 230 tons, which is about three times that of the Merlin 1D engine used on Falcon 9. The high thrust and high specific impulse of the Raptor engine can effectively make up for the weight loss caused by stainless steel.<\/p>\n
4. Analysis of various types of stainless steel<\/p>\n
(1) 301<\/p>\n
301 stainless steel is a metastable austenitic stainless steel that has a complete austenitic structure under sufficient solid solution conditions. Among stainless steels, 301 is the steel type that is most easily strengthened by cold deformation. The strength and hardness of the steel can be improved through cold deformation processing. It has good rust resistance under atmospheric conditions, but has poor corrosion resistance in chemical media. 301 stainless steel contains slightly lower chromium and nickel than 304 stainless steel, but it can obtain a tensile strength of up to 1500MPa through cold work hardening. In addition, 301 stainless steel has excellent elasticity and wear resistance in the cold-rolled hardened state, and is especially suitable for scenarios that require high strength and certain corrosion resistance.<\/p>\n
(2) 304\/304L<\/p>\n
304 series stainless steel is the most versatile and widely used of all stainless steels. 304\/304L stainless steel accounts for more than 50% of the total domestic stainless steel consumption. Its excellent comprehensive performance and relatively low cost make it the material of choice in the civil and industrial fields. 304 stainless steel (0Cr18Ni9) is a general-purpose stainless steel with a carbon content of \u22640.08%; 304L (00Cr19Ni10) is a low-carbon version with a carbon content of \u22640.03%. The low carbon content makes 304L better resistant to intergranular corrosion in welding and corrosion-sensitive environments, and is especially suitable for occasions requiring welding processing.<\/p>\n
(3) 316L<\/p>\n
316 series stainless steel is an improved version of 304 stainless steel. It is an upgraded steel type formed by adding 2-3% molybdenum (Mo) to 304. The addition of molybdenum significantly improves the material’s resistance to pitting and crevice corrosion in chloride environments, but the addition of molybdenum also significantly increases the material cost, which is one of the reasons why the cost of 316L stainless steel is relatively high. 316 series stainless steel has higher strength and better creep resistance at high temperatures than 304 system stainless steel. Series 316 stainless steel also offers excellent mechanical and corrosion properties at sub-zero temperatures. As a representative of high-end austenitic stainless steel, 316L stainless steel has an irreplaceable status in harsh environments due to its excellent corrosion resistance and good high-temperature strength.<\/p>\n
5. Analysis of domestic stainless steel suppliers<\/p>\n
my country’s stainless steel material suppliers present a multi-level and diversified competitive landscape. They include large-scale state-owned steel groups that dominate the domestic stainless steel market relying on strong financial strength, complete industrial chains and national policy support; professional stainless steel manufacturers that focus on stainless steel market segments and have formed competitive advantages in specific fields with their flexible operating mechanisms and professional market positioning; and regional leading enterprises that have deeply cultivated regional markets and won customers with fast supply responses and complete after-sales services.<\/p>\n
(1) Large state-owned steel groups<\/p>\n
1. China Baowu Steel Group<\/p>\n
Baowu Group has an annual production capacity of 800,000 tons of cold-rolled stainless steel. Its products cover 200, 300, and 400 series, and its surface processing accuracy includes 2D, 2B, NO.1, NO.2, HL, BA, 8K and other types. Its Baosteel Co., Ltd. Stainless Steel Division and Guangdong Donghong Stainless Steel Materials Co., Ltd. focus on the production of high-end stainless steel plates, especially in the field of 316L nuclear power grade stainless steel, which has technological leadership. In addition, Baowu Group (including Taigang and Baoxin) is also a major supplier of 304\/304L stainless steel plates, with an annual production capacity of one million tons.<\/p>\n
2. Taiyuan Iron and Steel<\/p>\n
TISCO is my country’s earliest professional stainless steel manufacturer and has traditional advantages in the field of military and aerospace grade stainless steel. The 301 stainless steel products developed by TISCO have a high share in the fields of rail transit and aerospace structural parts. The products comply with various standards such as Chinese GB, American ASTM, Japanese JIS, and German DIN. Some people used to complain that our country could not even produce ballpoint pen refills. In September 2016, Taiyuan Iron & Steel Co., Ltd. installed Chinese refills on its ballpoint pens.<\/p>\n
3. Ansteel Lianzhong (Guangzhou) Stainless Steel Co., Ltd.<\/p>\n
Ansteel Lianzhong (Guangzhou) Stainless Steel Co., Ltd. focuses on the production of high-end stainless steel, especially in the fields of 304L and 316L ultra-low carbon stainless steel, with technical advantages. The company’s products are widely used in fields such as chemical containers, food processing equipment, and medical equipment that require extremely high purity of materials.<\/p>\n
(2) Professional stainless steel manufacturer<\/p>\n
1. Qingshan Holding Group<\/p>\n
Tsingshan Holding Group is one of the world’s largest stainless steel manufacturers, achieving cost leadership through its entire industry chain layout and technological innovation. On the one hand, Tsingshan Group adopts self-developed short-process technology in the field of 316L stainless steel. On the other hand, by using recycled scrap steel and its own ferronickel resources, Tsingshan Group has significant advantages in cost control. It occupies the mid-range market with high cost performance and gradually expands to high-end fields.<\/p>\n
2. Zhangjiagang Pohang Stainless Steel Co., Ltd.<\/p>\n
Zhangjiagang Pohang Stainless Steel Co., Ltd. is a joint venture established by South Korea’s POSCO (82.5%) and Jiangsu Shagang Group (17.5%). It has introduced core equipment such as a 20-roll Sendzimir rolling mill (DMS, France) and a continuous annealing and pickling line (Germany\/Netherlands) to achieve intelligent control of the entire process. The surface accuracy of cold-rolled sheets reaches BA and 8K mirror levels. The company has an annual production capacity of 400,000 tons of cold-rolled stainless steel and 600,000 tons of hot-rolled stainless steel. It focuses on high-end 300 series stainless steel, including 316L (resistant to chloride ion corrosion), 304L (low carbon welding type) and the patented product 301TK (high elongation steel for water tanks).<\/p>\n
(3) Regional leading enterprises<\/p>\n
1. Shenzhen Boxheng Metal Materials Co., Ltd.<\/p>\n
Shenzhen Boxheng was established in 2005 and is a leading stainless steel supplier in Guangdong Province. It has passed ISO9001 and ISO14001 system certification. The company maintains a large amount of spot inventory, including 316L stainless steel rods, 301 stainless steel strips, etc., to provide rapid supply services to customers in the Pearl River Delta region. With its inventory advantage and rapid response capabilities, Shenzhen Boxeng has become an important stainless steel material service provider in South China.<\/p>\n
2. Shenzhen Great Wall Stainless Steel Materials Co., Ltd.<\/p>\n
Shenzhen Great Wall Stainless Steel Materials Co., Ltd. was established in 1998. It specializes in stainless steel products made of various materials such as 301, 304\/304L, 316\/316L, etc. It has passed the American Elvi ISO9001:2000 international quality management system certification.<\/p>\n
6. Processing technology of stainless steel plates<\/p>\n
(1) Steel plate rolling<\/p>\n
There are two production methods of steel plates: cold rolling and hot rolling. The difference lies in whether the plate is heated during the rolling process. Cold rolling has obvious cold hardening phenomenon and is usually used for the production of thin-walled plates; hot rolling processing technology is more complicated and is often used for the processing of medium-thick plates. Generally, the performance of cold-rolled austenitic stainless steel plates meets the national standard requirements, that is, it meets GB\/T 3280-2015 stainless steel cold-rolled steel plates and steel strips. Hot-rolled plates must be strictly inspected and controlled to contain martensite, because martensite has a great effect on the low-temperature properties of austenitic stainless steel materials.<\/p>\n
(2) Welding<\/p>\n
The welding processes of austenitic stainless steel mainly include gas tungsten arc welding (TIG), metal arc welding (MIG), manual arc welding\/(SWAM), submerged arc welding (SAW), and flux-cored arc welding (FCAW). When welding austenitic stainless steel, because of its low melting point, small thermal conductivity, and large resistance coefficient, the base metal and welding materials are easily heated and melted during welding, so the welding current used is relatively small, only about 80% of that of ordinary carbon steel. At the same time, narrow welds and narrow weld beads should be used to reduce high temperature residence time, prevent carbide precipitation from affecting corrosion resistance, reduce weld shrinkage stress, and reduce hot crack sensitivity.<\/p>\n","protected":false},"excerpt":{"rendered":"
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