1. Scope
This national standard specifies designation and its chemical constitution of stainless steel and heat resisting steel (see Table 1 ~ table 5). physical parameter of some designations, overseas standards designation or approximate designation parallel table, stainless steel and heat resisting steel designation criterion of acceptability are stipulated in the Informative Annex.
Chemical constitution liminal value and its designation time stipulated in this standard is applicable to formulate and its revise product standard for stainless steel and its refractory steel (including steel ingot and its half-finished product).
2. Terminology and definition
The following terminology and definition are is applicable to this standard.
2.1
Stainless steel
Stainless steel does not rust and corrosion-resistant. Chromium content is at least 10.5%; carbon content is at maximum 1.2%.
2.1.1
Austenitic grade stainless steel
Base is with face-centered cubic crystal austenite structure (gamma phase), antimagnetic. This kind of stainless steel is intensified (may cause magnetism) through cold-working.
2.1.2
Austenitic-ferritic (duplex) grade stainless steel
Base is with austenite and ferrite (one with less phrase is more than 15%). the stainless steel is with magnetic property and can be intensified through cold-working.
2.1.3
Ferritic grade stainless steel
Base is with space centered cubic lattice iron chain tissue (alpha phase) and with magnetic property. It cannot be hardened through heat treatment, but cold-working can lightly intensify it.
2.1.4
Martensitie grade stainless steel
The base is the magnetic martensitic structure. Through heat treatment, mechanical property can be adjusted.
GB/T 20878-2007 The following standards are cited：
