SUS 420J1 Stainless Steel: Excellent Hardness and Wear Resistance

SUS 420J1 stainless steel is highly regarded in industrial applications for its exceptional hardness and superior wear resistance, properties that are fundamentally achieved through precise heat treatment. Unlike austenitic stainless steels, whose properties are primarily derived from their chemical composition, the key mechanical characteristics of this martensitic grade are unlocked through a controlled process of hardening and tempering.

The journey to peak hardness begins with austenitizing, where the material is heated to approximately 980-1050°C, allowing carbon to dissolve into the austenitic matrix. Subsequent rapid quenching, typically in oil or air, transforms this structure into hard, metastable martensite. In this as-quenched state, the material is very hard but also brittle. The critical final step is tempering, where the steel is reheated to a specific temperature. To maximize hardness and wear resistance, tempering is conducted at relatively low temperatures, often between 150-300°C. This process relieves internal stresses without causing a significant drop in hardness, enabling SUS 420J1 to reliably achieve a remarkable hardness range of HRC 50-55.

This high hardness directly translates into outstanding resistance to abrasive wear, plastic deformation, and surface gouging. This makes SUS 420J1 stainless steel an ideal and cost-effective choice for a wide array of demanding components. Its performance is proven in applications such as cutting blades, surgical instruments, bearing surfaces, and mechanical seals, where maintaining a sharp edge and dimensional stability under frictional stress is paramount. Ultimately, the combination of achievable high hardness and resultant wear resistance defines SUS 420J1 stainless steel core value proposition for precision wear components.