SUS440B: Avoiding 440-Series Substitutions

SUS440B is a separate martensitic stainless grade within the 440 series. Material reference.

Avoiding 440-Series Substitutions

If a replacement bearing or cutting component is specified as 440B, confirm availability before accepting a quote based on 440A or 440C. An apparently similar hardness target does not itself establish interchangeability of the materials and their final properties.

Manufacturing and acceptance checks

Require the complete material designation and certificate. Define hardness, dimensional stabilization and surface finishing in the process plan. For the first article, inspect the actual contact surfaces and test the component against the original wear or running requirement before approving a substitute grade.

Compare related options

• SUS440A
• SUS440C

Reference and scope

Daido: JIS stainless grade identities and chemistry provides material or specification background. The checks above are purchasing guidance; final acceptance values must come from the agreed grade, product specification and condition.

Send a drawing and material requirements for review. Include quantity, critical dimensions and the inspection evidence required with delivery.