"Striver", a deep-sea manned submersible, successfully completed a 10,000-meter sea trial and returned home on the 28th. The Titanium alloy team of the Institute of Metal Research, Chinese Academy of Sciences has built the world's largest and most manned submersible capsule capsule for striver using the self-invented Titanium alloy Ti62A new material.

Break through technical barriers

The manned capsule is the core and key component of the manned submersible in the whole sea depth. It is the hardware guarantee and safety barrier for human to enter the deep sea of ten thousand meters, marking the technical level of a country's manned submersible. Previously, the world's most advanced all-sea submersible was the "limiting factor" for the us to complete a 10,000-meter dive in May 2019, with a manned capsule capable of carrying two people.

With the special support of the Chinese Academy of Sciences as a strategic pilot, the Institute of Metals and Metals of the Chinese Academy of Sciences began to carry out research and demonstraTion and advance research on key technologies such as materials and manufacturing of manned capsules for deep-sea manned submersions in 2014. National key project research and development plan in 2016, the Chinese Academy of Sciences institute of metal lead, joint treasure Titanium co., LTD., China shipping group co., LTD. Luoyang shipping material research institute, China aviation industry manufacturing technology research institute and the deep sea science and engineering research institute, Chinese Academy of Sciences, the technical advantages of each unit, to form a whole sea deep manned space development "national team" Titanium alloy, the three-year fully completed the development work, successfully built the world's largest, capable of carrying three people full of deep sea manned tank.

The research team has solved a number of basic scientific problems of Titanium alloy and overcome a series of key technical bottlenecks of manned capsule materials, forming, welding and so on.

First of all, the new Titanium alloy Ti62A created by metal has successfully solved the problems of strength, toughness and weldability faced by the materials of the manned capsule. In the past, deep submersibles mainly used Ti64 materials, which were impossible to reach in terms of strength, toughness and other indicators according to the target size and thickness requirements of manned capsules under extreme pressure conditions at a depth of 10,000 meters. Metal for the first time put forward a new type of alloy design scheme, design and implement a new Titanium alloy microstructure, on the basis of the invention has good thermal forming and welding performance of Titanium alloy Ti62A, toughness and weldability with Ti64 alloy under the premise of greatly increased strength, has successfully solved the manned space spherical shell material problem.

Secondly, the uniformity and stability of mechanical properties of large - size ultra - thick Titanium alloy are solved. There is an inherent "size effect" in Titanium alloy material, that is, the larger the size and thickness, the more difficult it is to guarantee the uniformity and mechanical stability. This is an obstacle that must be surmounted for use in extreme high-pressure environments in the deep sea. The size effect of Titanium alloy was successfully overcome by designing the microstructure of the materials and its acquisition process, which laid a technical foundation for the realization of uniform microstructure and stable mechanical properties of the materials in the manned capsule. BaoTi co., LTD has made every effort to exert its equipment capacity to the extreme, and has prepared high-quality ingot, high-quality plate and high-precision hemisphere, which has created a number of records such as the weight of Titanium alloy ingot, plate thickness and forging section size in China.

Thirdly, it breaks through the welding technology of high strength and high toughness Titanium alloy, ensuring the toughness of weld and other related indexes meet the requirements. The manned capsule consists of two hemispheres welded together (equatorial joints) and several windows and interfaces (hole seats) must also be welded. It is a worldwide problem for welding technology to ensure that the toughness of weld position can meet the requirements. It is an insurmountable obstacle in front of the task to realize one-time welding of all-electron beam with super large size and thickness materials. Some new welding ideas have been put forward by metal institute. Luoyang Ship materials InsTitute has made innovations and made breakthroughs in a series of welding forming technologies to realize the full electron beam welding of the manned capsule, ensuring that the quality and strength of the welding seam meet the design requirements.

Work together to overcome difficulties

The research and development of the deep-sea manned capsule has a large span of technology, and the time is pressing. From the trial production of materials, engineering verification, component manufacturing to the parallel development of welding technology, the task is very heavy, and the difficulty of coordination and decision making is unprecedented. Project directors, Mr. Yang Rui as former director of Titanium alloy branch of  the Chinese Academy of Sciences metal;  Mr. Jia Shuanxiao as general manager and Mr. Wang Dingchun as deputy general manager from Baoji Titanium Industry Co. LTD; Mr. Wang Qihong and Mr. Liao Zhiqian as deputy directors of the institute of luoyang ship material work leading group, they forged a strong in the common struggle of collective leadership, have the courage to bear, the tail from wagging the dog, precision, vigorously promotes the implementation, technical bottlenecks, once severe tardiness in team lost time lead you back to mission beginner's mind, every team member deep enlightenment govinda deep solemn mission and reaching the top of the career into infinite power, It has truly fulfilled the requirement of Mr.Ding Kang, the leader of the overall expert group on "key technologies and equipment of deep sea", "only tasks, no companies". In the face of difficulties, they are full of optimism and triumphalism, shoulder the pressure, strive for psychological space for the team to tackle problems, and create a relaxed atmosphere. In a major technical obstacles analysis meeting, Mr.Sun Qing as director the 21st century agenda management center ocean said: "the difficulties and innovation path, faced with such serious situation, Mr. Yang Rui can joke at the meeting, the sun also rises, the outlook remains light, I must win confidence to conquer difficulties, full of expectation" manned space for delivery.

Mr.Lei Jiafeng, the front-line coordinator of the project and deputy director of the Titanium alloy Research Department of the InsTitute of Metal Research of the Chinese Academy of Sciences, coordinated and supervised the development of the manned capsule on the site and witnessed the whole process. He was also full of deep sea manned submersibles, deputy chief designer, should carry through the mission requirements, the implementation of the process, and to contact the overall unit, supervision unit and the panel, I concentrate on the flapping in the project task, don't pass every link, do not ignore any details, once fought north and south, creating the record of more than a month to go home. He is good-natured, patient and meticulous in work, and is praised as "the toughness is as good as the high-strength and high-toughness Titanium alloy invented by metal". Project backbone, Chinese Academy of Sciences metal institute Mr.Ma Yingjie, in the face of technical problems spirit, regardless of day and night to fight in the scientific research post, put forward to ensure the toughness of the composite sheet layer of microscopic organization design scheme. When the impact toughness data tested by the four units were inconsistent, he lived in the laboratory for three consecutive days, worked overtime to analyze the similarities and differences of samples, carried out performance tests twice as often, came up with correct conclusions in the shortest time, and unified testing methods, which ensured the progress of the project.

Ms. Wang Yongmei, technical coordinator of Baoji Titanium Industry Co. LTD, is technically strict and insists on taking data. As for the batch difference of welding wire, she sacrificed the weekend reunion time with her family and worked overtime to analyze. Finally, she traced the "prime culprit" of the problem caused by excessive hydrogen content and solved it in a timely way, thus resolving the major technical risk. Because the plate specification has reached the limit of heating furnace and rolling mill, in order to ensure the success, BaoTi shares self-raised funds to upgrade the equipment, strict maintenance, fully reflects the old state-owned enterprise's spirit of ownership.

At the beginning of the welding test project a major setback, luoyang insTitute of ship material reimbursing, team members to give up the Spring FesTival break, "three shifts" continuous operation, the new director Liu Yanjiang quickly informed, battalions, strives for perfection, don't pass a spark, dedicates to mobilize support, with great courage and bear decision clappers, ensure the back wall. Hu Weimin, director of the eighth research office, repeatedly deliberated the technical plan, carefully organized and implemented, and finally conquered the difficulties and completed the scientific research task with both quality and quantity guaranteed. Lu Yifan, the technical backbone, has the courage to innovate in the case that several rounds of tests are needed to obtain the necessary data for pre-heating welding, and the test materials cannot be timely put in place. He proposed the test block mosaic method, which ensures the development progress and saves a lot of test materials.

Mr. Mao Zhiyong, deputy chief engineer of Avic Manufacturing Technology Research Institute, persisted in his work despite of illness and made outstanding efforts for the implementation of the plan as planned. Zhang Hailong and Jiang Lei, from the Institute of Deep Sea Science and Engineering under the Chinese Academy of Sciences, worked hard to keep the pressure test unit in the best condition during the entire suppression test. They all made unique contributions to the development of the manned capsule.

Drive industrial upgrading

The development of deep-sea manned capsule has greatly promoted the improvement of Titanium alloy industrial capacity and equipment manufacturing technology in China. High strength and high toughness Titanium alloy ingot size, plate width and thickness, Titanium alloy hemispheric thickness, forging section and single weight, Titanium alloy electron beam weld thickness and other technical indicators have broken the original domestic record, close to the limit capacity of the equipment. The technology of electron beam welding and heat treatment of super-thick and high-strength Titanium alloys has achieved technological leap-forward. The transformation and promotion of these manufacturing capabilities will significantly improve the application level of Titanium alloys in the fields of naval ships, marine engineering and petrochemical industry in China. These new technologies can be promoted and applied to other Titanium alloys, promoting the industrial application of Titanium alloys on a larger scale, creating new economic and social benefits for enterprises, and speeding up the pace of the industry towards the high-end of the industrial chain. From 2018 to 2019, the sales amount of BaoTi Co., Ltd. in extra-thick plates, large-section single-heavy forgings and pressure-resistant structural equipment exceeded 150 million yuan.

The success of the development of the whole sea deep manned capsule fully reflects China's institutional advantages of concentrating its efforts to accomplish great things, and it has written a brilliant song of success for the "national team" of Titanium alloy scientific research and production in the new era, making concerted efforts, striving for strength, pioneering in no man's land, and occupying the commanding heights of deep-sea technology. The manned capsule development team with the courage to climb to the top of the innovative achievements show the new era strivers good image.