日前，在大连船舶重工集团有限公司船坞内，一艘17.5万立方米级液化天然气（LNG）运输船正在建造，银光闪闪的特种钢板被精准焊接。现场技术人员介绍，建造LNG运输船的钢材，既要承受船体结构的巨大载荷，又要经受零下163摄氏度的极寒考验。

Recently, in the shipyard of Dalian Shipbuilding Industry Group Co., Ltd., a 175,000 cubic meter liquefied natural gas (LNG) transport ship was under construction. The shiny special steel plates were precisely welded. The on-site technicians explained that the steel used for building the LNG transport ship has to withstand the huge load of the ship's structure and also endure the extremely cold conditions of minus 163 degrees Celsius.

目前，中国宝武太原钢铁（集团）有限公司（以下简称“太钢”）研制的MARK-Ⅲ型LNG运输船薄膜围护系统专用不锈钢，已批量应用于该船核心低温结构与围护系统，填补了国内高端船用特种钢材的技术空白，这款“低温铠甲”为国产LNG运输船提供了硬核科技支撑。

At present, the special stainless steel for the membrane enclosure system of the MARK-Ⅲ type LNG transport ship, developed by China Baowu Taiyuan Iron and Steel (Group) Co., Ltd. (hereinafter referred to as "Taigang"), has been widely applied to the core cryogenic structures and enclosure systems of this ship. This has filled the technological gap in high-end ship-specific special steel in China. This "cryogenic armor" provides strong technological support for domestic LNG transport ships.

在常压下，LNG需在零下163摄氏度至零下162摄氏度的超低温下维持液态，体积缩小约600倍后才能跨洋运输。LNG运输船液货舱长期承受极低温与近200摄氏度的舱内外温差，还要抵御航行中风浪引发的液体晃荡冲击。

At normal pressure, LNG must remain in a liquid state at extremely low temperatures ranging from -163 degrees Celsius to -162 degrees Celsius. It needs to shrink by approximately 600 times in volume before it can be transported across the ocean. The liquid cargo tanks of LNG transport ships have to endure extremely low temperatures and a temperature difference of nearly 200 degrees Celsius between the inside and outside of the tanks. They also have to withstand the shock of liquid sloshing caused by wind and waves during the voyage.

普通船用碳钢在此工况下会失去韧性，变得像玻璃一样脆，且热胀冷缩会直接撕裂焊缝。因此，LNG运输船液货舱必须使用具备优异低温韧性、抗疲劳、耐腐蚀等性能的特种钢材。

Under this working condition, ordinary marine carbon steel will lose its toughness and become as brittle as glass. Moreover, thermal expansion and contraction will directly tear the welds. Therefore, the liquid cargo tanks of LNG transport ships must be made of special steel with excellent low-temperature toughness, fatigue resistance, corrosion resistance, etc.

太钢技术中心新能源用不锈钢主任研发师李阳坦言，长期以来，LNG运输船液货舱内衬核心材料依赖进口，技术壁垒高、供货周期长、价格波动大。

Li Yang, the director of R&D at the New Energy Stainless Steel Department of Taiyuan Iron and Steel Technology Center, stated frankly that for a long time, the core material for the inner lining of LNG transport ship liquid cargo tanks has relied on imports. The technical barriers are high, the supply cycle is long, and the price fluctuates greatly.

面对这一难题，太钢集中研发力量开展技术攻坚。经过无数次试验与实船验证，太钢攻克了LNG运输船货舱内衬核心材料所用高端超低温不锈钢生产技术，成为国内首家、全球第三家掌握该核心材料量产技术的企业，填补了国内在这一方面的技术空白。

Facing this challenge, Taigang concentrated its research and development efforts on conducting technological breakthroughs. After numerous experiments and tests on actual ships, Taigang successfully overcame the production technology for the core material used for the inner lining of LNG transport ships. It became the first domestic enterprise and the third global enterprise to master the mass production technology for this core material, filling the technological gap in this field in China.

太钢研制的这款MARK-Ⅲ型LNG运输船薄膜围护系统专用不锈钢，厚度仅1.2毫米，属于特制奥氏体不锈钢，拥有独特的面心立方晶体结构，在极低温下仍能保持稳定韧性，避免低温脆断。李阳介绍，这款不锈钢中的铬元素可形成致密钝化防护膜，能抵御超低温介质与海上湿气的腐蚀，其中的镍元素能稳定钢材内部晶体组织，确保材料历经数百次冷热循环后性能不衰减。针对不锈钢热膨胀系数偏高的短板，太钢研发团队创新优化结构设计，将超薄钢板轧制成波纹褶皱造型，通过褶皱自主拉伸收缩抵消温差形变，无需增设复杂缓冲结构，提升了舱体结构的稳定性与耐久性。

The special stainless steel used by Taigang for the membrane enclosure system of this MARK-Ⅲ type LNG transport ship has a thickness of only 1.2 millimeters. It is a specially made austenitic stainless steel with a unique face-centered cubic crystal structure. It can maintain stable toughness even at extremely low temperatures, preventing brittle fracture due to low temperatures. Li Yang explained that the chromium element in this stainless steel can form a dense passivation protective film, which can resist corrosion from ultra-low temperature media and sea moisture. The nickel element in it can stabilize the internal crystal structure of the steel, ensuring that the material's performance does not deteriorate after hundreds of cold and hot cycles. In response to the shortcoming of the high thermal expansion coefficient of stainless steel, the R&D team of Taigang innovatively optimized the structural design. They rolled the ultra-thin steel plate into a wavy folded shape and used the folds to independently stretch and contract to counteract temperature-induced deformation. No complex buffering structures were added, which enhanced the stability and durability of the cabin structure.

从技术攻坚、工艺优化，到实船应用、批量供货，太钢造“低温铠甲”，正为我国高端LNG运输船产业挺起坚实的钢铁脊梁，这也是我国钢铁行业转型升级、高端制造自主自强的缩影，更是我国船舶工业从技术“跟跑”向全球“并跑”跨越的见证。

From technological breakthroughs and process optimization, to practical ship applications and mass production, Taiyuan Iron and Steel has produced "low-temperature armor", which is providing a solid steel backbone for China's high-end LNG transport ship industry. This is also a reflection of the transformation and upgrading of China's steel industry and the self-reliance and strength in high-end manufacturing. It is also a witness to China's shipbuilding industry's transition from "following the lead" in technology to "keeping pace" globally.