# Investigation of Impact Behavior of STS304L Steel Plate Under Cryogenic Temperature
## 1 Introduction  
With the accelerating global transition to clean energy, interest in liquefied natural gas (LNG) continues to grow. LNG, primarily composed of methane, is stored and transported in liquid form at an extremely low temperature of approximately \(-163\)\({}^{\circ}\)C to maximize efficiency and minimize its volume. However, maintaining LNG in its liquid state under such extreme cryogenic conditions requires advanced insulation and containment technologies to ensure safe and reliable transportation [1]. LNG carriers are equipped with specialized insulation systems designed to withstand the harsh conditions of maritime transport. These systems must endure loading stresses from wave-induced motions and environmental factors such as temperature fluctuations. Therefore, insulation systems play a crucial role in minimizing heat ingress, preserving the structural integrity of containment systems, and preventing LNG leakage [2, 3]. Among the most widely used LNG containment technologies is the Mark III system, which ensures both thermal integrity and structural stability. This insulation system typically incorporates materials such as STS304L stainless steel, plywood, and reinforced polyurethane foam [4, 5]. Each material plays a distinct role in maintaining the system's thermal insulation performance, mechanical strength, and overall durability [6]. A key component of this insulation system is the primary barrier, which is in direct contact with the LNG cargo. Typically made of STS304L stainless steel, the primary barrier serves as the first line of defense against potential leaks while also ensuring the structural integrity of the containment system under various loading conditions [7]. Given its exposure to cryogenic temperatures, impact forces, and cyclic loadings, the primary barrier must exhibit a high mechanical reliability to withstand these challenges. Despite its advantages, the structural integrity of STS304L can be compromised under repeated or sudden impact loadings. LNG carriers are subjected to sloshing loads, where the movement of the LNG inside the cargo tanks generates transient impact forces on the containment system. Over time, localized deformation, fracture initiation, and progressive damage accumulation can occur, weakening the primary barrier and potentially affecting long-term performance [8]. Owing to these concerns, extensive research has been conducted on the mechanical behavior and impact resistance of STS304L. [PERSON] et al. investigated the impact toughness of AISI 304L stainless steel at cryogenic temperatures, focusing on the effects of stacking fault energy and strain-induced martensitic transformation on fracture behavior [9]. Their study found that the impact energy of 304L stainless steel gradually decreased as the temperature dropped. [PERSON] et al. investigated the failure mechanisms of STS304L primary barriers under cyclic impact loads, identifying localized necking, ductile failure, and shear failure as key damage modes [10]. [PERSON] et al. examined the impact response of STS304L corrugated sheets in LNG cargo containment systems [11]. They demonstrated that the accumulated damage due to repeated impacts compromised structural integrity over time. [PERSON] et al. investigated the stress and strain distributions in membrane-type LNG cargo tanks under high-sea conditions, highlighting the structural vulnerabilities of STS304L under repeated loading and defective conditions [12]. [PERSON] and [PERSON] evaluated the low-temperature impact behavior of AISI 304L stainless steel and compared its impact resistance at different temperatures [13]. The results showed that the impact energy decreased as the temperature dropped, with the lowest impact energy observed at \(-80\)\({}^{\circ}\)C.  
Although extensive research exists, studies on the drop-weight impact testing of STS304L under extreme cryogenic conditions remain limited.