420 M Stainless [PDF]

Citation preview

Mold Die Steel DATA SHEET



A. Finkl & Sons Co. ¨



TYPE 420M STAINLESS STEEL Cleanest...Toughest...Most Machinable Available by Patented* Vacuum Arc Degassing (VAD) Process and Balanced Deoxidation Techniques



Typical Composition 420M (AISI 420 Mod) Carbon 0.35 Chromium 13.0 Manganese 0.50 Molybdenum 0.50 Silicon 0.35 Phosphorus 0.040 Max Micro-alloy Additions Sulphur 0.006 Max Finkl 420M is a martensitic stainless steel for plastic molds where high wear resistance and polishability are required in addition to corrosion resistance.



Finkl 420M is ALWAYS forged with a minimum of 5 to 1 reduction. It is sold in the annealed condition, with a hardness of approximately 200 on the Brinell scale, but may also be pre-hardened. Finkl 420M stainless steel is forged utilizing wide die techniques which assure consolidated centers and fine grain structure, resulting in improved properties throughout. Finkl 420M of Premium Quality is produced by the patented Double Vacuum Process, which consists of Vacuum Arc Degassing followed by Vacuum Arc Remelting. This process offers extraordinary cleanliness and a more unform distribution of alloys (see 420M Premium Quality Data Sheet).



Finkl 420M is 100% ultrasonically tested according to the most rigorous standerds. It is fully warranted for a molds and dies. The chemical composition of standerd 420 stainless has been modified in order to enhance corrosion performance. Molybdenum is added for carbide forming for improved strength, and improved corrosion resistance stabilizing element. The overall package is the best 420 type stainless steel availible. Applications Finkl 420M is recommended for plastics, glass, and other materials requiring molds exhibiting exellent polishability. The addition of the molybdenum improves the corrosion resistance of 420M versus AISI 420. This may reduce or eliminate the need to chrome plate molds in order to avoid corrosion. Premium quality 420M is especially recommended for plastic lense or other high quality optical applications. (See 420M Premium Quality Data Sheet). Finkl 420M heattreated to high hardness (40+ HRC) is also recommended for molding abrasive, filled plastics.



Recommended Heat Treatment Practice Process



Cooling (Quenching)



Temperature



Slow cool in furnace Slow cool to [875 °F] (470 °C), then in air



1425-1500 °F (775-815 °C) 50-100 °F (30-55 °C) below final tempering temperature



Annealing Stress Relieving



700-1225 °F (370-660 °C)



Preheating Hardening



Preheat in two stages



1850-1950 °F (1010-1065 °C) soaking 30 min.



Tempering



Oil or salt bath [650-850 °F] (340-450 °C) Air



CVN Absorbed Energy(ft.lbs.)



Rockwell C Hardness



See figure 1.; hold 1hr. per inch (25 min. per cm) of thickness



TemperingTemperature(°F)



420M



AISI 420



Testing Temperature(°F)



(°C)



(°C)



Finkl 420M exhibits improved toughness over AISI 420 stainless steel. The DBTT curve illustrates 420M's increased impact toughness at all test temptures. Double Vacuum Processing of 420M Premium Quality increases the toughness even further--resulting in molds and dies with greater resistance to cracking and catastrophic failure.



Thermal Properties of 420M Hardened and Tempered to 50 Rockwell C 70 °F (21 °C) 400 °F (204 °C) 750 °F (399 °C) Temperature Coefficient of thermal expansion 6.4(11.52) 6.1(10.98) [x10°/°F] (x10 /K) Thermal conductivity [Btu.in/ft -hr. °F] (W/m-k) 2



Specific Heat [Btu/lb. °F] (J/kg.K)



CHICAGO Phone: (773)975-2510 Toll Free: (800)621-1460 Fax: (773)348-5347



LOS ANGELES Phone: (562)861-2266 Toll Free: (800)248-0551 Fax: (562)923-6922



CLEVELAND Phone: (330)630-9601 Toll Free: (800)461-3436 Fax: (330)630-9693



MINNEAPOLIS Phone: (612)724-8967 Toll Free: (888)724-8967 Fax: (612)724-8968



DETROIT Phone: (810)756-3777 Toll Free: (800)367-4720 Fax: (810)757-3048



ST. LOUIS Phone: (612)724-8967 Toll Free: (888)521-1414 Fax: (314)521-1245



163(23.5)



170(24.5)



176(25.4)



0.11(460.5)



A Finkl & Sons Co



WWW.FINKL.COM



One Finkl Plaza (2011 N Southport Ave.) Chicago, IL 60614-4079 Phone: 773/975-2510 FAX 773/348-5347 Toll free phone: 1-800-DIE-BLOCK



PRODUCT WARRANTY The material herein merely constitutes instructions furnished gratuitously for your consideration. These instructions are intended as suggestions only and do not purport to be complete or to replace or to constitute normal shop practices. A. Finkl & Sons Co. makes no representation or warranty of any kind, express or implied with respect to the matters covered herein, whether as to merchantability, fitness for a particular purpose, reproducibility of properties and results set out herein, or any other matter. EXCLUSION OF WARRANTIES-THE IMPLIED WARRANTIES OF MERCHANTABILITYAND FITNESS FOR ANY PURPOSE ARE EXCLUDED.