Entc 207 Test 3 Review

Stainless Steels: must have at least 10% chromium A. Ferritic Stainless Steels: Iron, chromium + low carbon a. Magnetic b. Lowest cost c. Non-hardenable i. Can be annealed d. BCC structure e. Low carbon ii. Less than .2% f. Chromium content iii. 16-20% g. B. Martensitic Stainless Steel: iron, chromium + higher carbon h. Magnetic i. Martensitic Structure j. Hardenable k. High Carbon iv. Up to 1.2% l. Chromium v. 12-18% m. Poor Weldability and notch sensitivity n. Used for applications with corrosion resistance and wear resistance C. Austinitic Stainless Steel: iron, chromium, nickel + low carbon o. All 3xx are austenitic and are nickel chromium alloys p. Non-Magnetic unless cold worked q. Non-Hardenable vi. Can be annealed and stress relieved r. Very low Carbon Content s. Chromium vii. 16-26% t. Nickel viii. 8-24% u. Can be hardened by cold working v. 304 is the most widely used stainless steel in industry
Physical and Mechanical Properties * Density * About the same as carbon steel * Conductivity * Poor conductors of both heat and electricity * Thermal conductivity of stainless is about half of carbon steel * Electrical resistivity of stainless steel can be as much as 6 times as much as carbon * Expansion * Austenitic (300 series): coefficient of thermal expansion is up to 50% greater than carbon steel * Modulus of elasticity * Slightly lower than carbon steel * Stainless Modulus: 28-29*10^6 psi * Carbon Steel: 30*10^6 psi * Mechanical Properties * 304 and 316: Better tensile, ductility, and toughness than mild steel * 420 and 440C: high hardness; used as tool steels * 310 or 446: best for scaling resistance