Import Big Section Steel 4140 Alloy Steel Flat Bar — Buy in wholesale FOB from Supplier in China

The 4140 Alloy Steel Flat Bar from Dongguan Songshun Mould Steel Co., Ltd. is a chromium-molybdenum alloy steel product supplied in big section dimensions for heavy-duty engineering applications. The material conforms to AISI/SAE 4140 with a carbon range of 0.38 to 0.45 percent, chromium 0.90 to 1.20 percent, and molybdenum 0.15 to 0.25 percent, offering greater strength and hardenability than 4130-grade equivalents. This grade is widely specified for components subjected to cyclic stress and moderate impact in machinery and automotive assemblies.

The higher carbon content relative to 4130 improves tensile strength and heat treatment response, while the chromium and molybdenum additions enhance toughness and resistance to temper brittleness. Standard supply formats include hot-rolled or forged flat bar in big section sizes, though exact dimensions (thickness, width, length) and tolerance classes (e.g. EN 10058 or ASTM A29) must be confirmed with the supplier. Typical surface conditions range as-rolled or peeled/turned, depending on subsequent machining requirements. The material exhibits good weldability with preheat and post-weld heat treatment protocols, and machines readily in the annealed condition.

Primary applications include connection rods, conveyor pins, gears, stem assemblies, pump shafts, and tool holders where a combination of strength, toughness, and fatigue resistance is required. The big section format suits heavy machinery frames, press platens, and large die sets where sectional mass carries structural load. Buyers should verify dimensional stock availability, mill test certificate provision, and whether the material is supplied in the normalised, annealed, or quenched-and-tempered condition. Heat treatment capability at destination, or supplier-provided heat treatment, should be discussed for critical applications.

Dongguan Songshun Mould Steel Co., Ltd. is located at No.4 Dongda Street, Sha Tou, Dongguan City, Guangdong Province, a manufacturing hub in China's Pearl River Delta with established metal processing and mould steel distribution networks. The supplier carries an imported tier and harbor trust tier on this platform. The response rate is recorded at 0.00 percent with zero average response hours, so direct outreach is essential to establish communication channels and assess technical competency in alloy steel specifications.

The company profile does not disclose mill relationships, stockholding capacity, heat treatment facilities, or third-party certification status (ISO 9001, ISO 14001, or mill accreditation). No stated headcount, revenue, or client list appears in the source data. Dongguan is a major centre for mould and die manufacturing, suggesting local market demand for 4140-grade material, but buyers should independently verify whether Songshun operates as a stockist-distributor or direct mill agent. Request mill test certificates, traceability documentation, and inspection reports for the specific heat or lot number under quotation.