VANADIS 10 SuperClean High performance powder metallurgical cold work tool steel

Transcription

1 SuperClean High performance powder metallurgical cold work tool steel

2 Critical tool steel properties for GOOD TOOL PERFORMANCE Correct hardness for the application Very high wear resistance Sufficient toughness to prevent premature failure due to chipping/crack formation. High wear resistance is often associated with low toughness and vice-versa. However, for optimal tool performance both high wear resistance and toughness are essential in many cases. VANADIS 1 is a powder metallurgical cold work tool steel offering a combination of extremely high wear resistance and good toughness. TOOLMAKING Machinability Heat treatment Dimensional stability in heat treatment Surface treatment. Toolmaking with highly alloyed steels means that machining and heat treatment are often more of a problem than with the lower alloyed grades. This can, of course, raise the cost of toolmaking. Due to the very carefully balanced alloying and the powder metallurgical manufacturing route, VANADIS 1 has a similar heat treatment procedure to the steel D2. One very big advantage with VANADIS 1 is that the dimensional stability after hardening and tempering is much better than for the conventionally produced high performance cold work steels. This also means that VANADIS 1 is a tool steel which is very suitable for CVD coating. Examples: Blanking and forming Fine blanking Blanking of electrical sheet Gasket stamping Deep drawing Cold forging Slitting knives (paper and foil) Powder pressing Granulator knives Extruder screws etc. General VANADIS 1 is a chromium-molybdenum-vanadium alloyed steel which is characterized by: Extremely high abrasive wear resistance High compressive strength Very good through-hardening properties Good toughness Very good stability in hardening Good resistance to tempering back. Typical C Si Mn Cr Mo V analysis % 2,9,, 8, 1, 9,8 Delivery condition Colour code Properties Soft annealed to approx HB Green/violet PHYSICAL DATA Hardened and tempered to 62 HRC. Applications VANADIS 1 is especially suitable for very long run tooling where abrasive wear is the dominating problem. Its very good combination of extremely high wear resistance and good toughness also make VANADIS 1 an interesting alternative in applications where tooling made of such materials as cemented carbide tends to chip or crack. Temperature 2 C C C (68 F) (39 F) (7 F) Density kg/m 3 7 lbs/in 3,268 Modulus of elasticity N/mm psi 31,9 x 1 6 3,4 x , x 1 6 Coefficient of thermal expansion per C from 2 C 1,7 x ,4 x 1-6 F from 68 F 6, x 1-6 6,3 x 1-6 Thermal conductivity W/m C 2 22 Btu in/(ft 2 h F) Specific heat J/kg C 4 Btu/lb F,11 2

3 IMPACT STRENGTH Approximate room temperature impact strength at different tempering temperatures. Specimen size: 7 x 1 x mm (,27" x,4" x 2,2") unnochted. Hardened at 12 C (187 F). Quenched in air. Tempered twice. Heat treatment SOFT ANNEALING Protect the steel and heat through to 9 C (16 F). Cool in the furnace at 1 C (2 F) per hour to 7 C (138 F), then freely in air. Impact energy (J) Hardness Hardness (HRC) 6 STRESS RELIEVING After rough machining the tool should be heated through to 6 C (1 F), holding time 2 hours. Cool slowly to C (93 F), then freely in air WEAR RESISTANCE Weight loss (mg/min) VANADIS 1 Impact energy 3 C F Tempering temperature (2h + 2h) D2 Pin on disc test. Disc material: SiC. VANADIS 1 = 62 HRC, D2 = 62 HRC. 4 HARDENING Pre-heating temperature: 7 C ( F) Austenitizing temperature: C ( F) Holding time: 3 mins. N.B. Holding time = time at hardening temperature after the tool is fully heated through. A holding time of less than 3 minutes will result in loss of hardness. The tool should be protected against decarburization and oxidation during hardening. QUENCHING MEDIA Forced air/gas Vacuum furnace (gas overpressure 2 bar) Martempering bath or fluidized bed at C (93 12 F) Martempering bath or fluidized bed at 3 C (39 6 F) whereby 3 C (6 F) is preferred. Note 1: Temper the tool as soon as its temperature reaches 7 C (12 1 F). Note 2: In order to obtain the optimum properties for the tool, the cooling rate should be as fast as is concomitant with acceptable distortion. Note 3: Tools with sections > mm (2") should be quenched in forced air. Quenching in still air will result in loss of hardness. Typical application area for VANADIS 1: high volume production of electrical components. 3

4 TTT-graph Austenitizing temperature 12 C (187 F). Holding time 3 minutes. Temperature F C M s Bainite Pearlite Austenitizing temperature: 12 C Holding time: 3 min. Ac 1f Ac 1s 1 M f Seconds Minutes Hours Iso- Hardness thermal Time HV1 temp. C hours (approx.) 4, , , , CCT-graph Austenitizing temperature 12 1 C ( F). Holding time 3 minutes. Temperature F C C M s M f Martensite Carbides Austenitizing temperature 12 C (187 F) Holding time 3 min. Pearlite Bainite Seconds Minutes Hours Air cooling of,2 1, 1 9 bars, Ø mm,79,9,394 3,4 23,6 inch AAc c1f 1f Ac c 1s 1s Cooling curve Hardness T No. HV 1 (sec) ,

5 Hardness and retained austenite as functions of austenitizing temperature. Holding time 3 min. Air-cooling. Hardness HRC Hardness Retained austenite Retained austenite % C F Temperature 1 1 DIMENSIONAL CHANGES AFTER HARDENING AND TEMPERING Specimen size: 6 x 6 x 6 mm (2," x 2," x 2,") Dimensional change, %,1,8,6,4,2, Hardening temperature 98 C 12 C 1 C 178 F 187 F 194 F As hardened C (39 F) C (12 F) Tempering temperature TEMPERING Choose the tempering temperature according to the hardness required by reference to the tempering graph. Temper twice with intermediate cooling to room temperature. Lowest tempering temperature 18 C (3 F). Holding time at temperature minimum 2 hours. At a hardening temperature of 11 C (21 F) or higher VANADIS 1 should be tempered at minimum 2 C (98 F) in order to reduce the amount of retained austenite Specimen size: 12 x 12 x 2 mm (" x " x 1") Dimensional change, %,1,8,6,4,2, As hardened C (39 F) C (12 F) Tempering temperature Tempering graph Hardness, HRC Retained austenite % Austenitizing temperature 1 C (194 F) 12 C (187 F) 11 C (21 F) Retained austenite 1 C (194 F) 1 Typical application for VANADIS 1. Tool for blanking and forming eletcrical strip. 3 C F Tempering temperature

6 SUB-ZERO TREATMENT Pieces requiring maximum dimensional stability can be sub-zero treated as follows: Immediately after quenching the piece should be sub-zero treated to between 7 and 8 C ( 9 to 11 F), soaking time 1 3 hours, followed by tempering. Sub-zero treatment will give a hardness increase of ~1 HRC. Avoid intricate shapes as there will be risk of cracking. NITRIDING Nitriding produces a hard surface layer that increases wear resistance and reduces the tendency towards galling. If high temperature tempered VANADIS 1 is normally tempered at 2 C (98 F). This means that the nitriding temperature used should not exceed 2 C (93 98 F). Ion nitriding at a temperature below the tempering temperature used is preferred. The surface hardness after nitriding is approximately 12 HV,2 kg. The thickness of the layer should be chosen to suit the application in question. Machining recommendations The cutting data below are to be considered as guiding values which must be adapted to existing local conditions. TURNING Turning with carbide Turning Cutting data Rough Fine with high parameters turning turning speed steel Cutting speed (v c ) m/min f.p.m Feed (f) mm/r,3,6,3,3 i.p.r.,1,24,1,1 Depth of cut (a p ) mm inch,8,24,8,8 Carbide designation ISO K1* K1* * Use a wear resistant Al 2 3 -coated carbide grade, e.g. Sandvik Coromant GC 31 or SECO TP. DRILLING High speed steel twist drill Drill diameter Cutting speed,v c Feed (f) mm inch m/min f.p.m. mm/r i.p.r. 3/16 8* 26*,8,2,3,8 1 3/16 3/8 8* 26*,2,3,8, /8 /8 8* 26*,3,3,12, /8 3/4 8* 26*,3,4,14,16 * For coated HSS drill v c 1 m/min. (3 f.p.m.). Carbide drill Type of drill Carbide Cutting data Indexable Solid tipped parameters insert carbide coolant-fed 1) Cutting speed (v c ) m/min f.p.m Feed (f) mm/r,,2 2),1,2 2),1,2 2) i.p.r.,2,1,4,1,6,1 1) Drill with internal cooling channels and brazed carbide tip. 2) Depending on drill diameter. MILLING Face and square shoulder milling Milling with carbide Milling with Cutting data Rough Fine high speed parameters milling milling steel Cutting speed (v c ) m/min f.p.m Feed (f z ) mm/tooth,2,4,1,2,1 in/tooth,8,16,4,8,4 Depth of cut (a p ) mm inch,8,2,8,8 Carbide designation ISO K1* K1* * Use a wear resistant Al 2 3 coated carbide grade, e.g. Sandvik Coromant GC 31 or SECO T1M. End milling Type of end mill Cutting data Solid Carbide index- High speed parameters carbide able insert steel Cutting speed (v c ) m/min ) f.p.m ) Feed (f z ) mm/tooth,3,2 2),8,2 2),,3 2) in/tooth,1,8 2),3,8 2),2,14 2) Carbide designation ISO K 2 K 1 3) 1) For coated HSS end mill v c 1 m/min (33 f.p.m.). 2) Depending on radial depth of cut and cutter diameter. 3) Use a wear resistant Al 2 O 3 -coated carbide grade. 6

7 GRINDING A general grinding wheel recommendation is given below. More information can be found in the Uddeholm publication Grinding of tool steel. Wheel recommendation Annealed Hardened Type of grinding condition condition Face grinding A 46 HV B17 R7 B3 1) straight wheel 3SG 46 GVS 2) C 46 GV Face grinding A 24 GV 3SG 46 FVSPF 2) segments A 46 FV Cylindrical grinding A JV B126 R7 B3 1) SG 7 IVS 2) C IV Internal grinding A 46 JV B17 R7 B3 1) 3SG JVS 2) C HV Profile grinding A 1 LV B17 R1 V 1) SG 8 JVS 2) C 12 HV 1) If possible, use CBN-wheels for this application. 2) Grinding wheel from Norton Co. Electrical-discharge machining EDM If EDM is performed in the hardened and tempered condition, finish with fine-sparking, i.e. low current, high frequency. For optimal performance the EDM d surface should then be ground/polished and the tool retempered at approx. 2 C ( F) lower than the original tempering temperature. When EDM ing larger sizes or complicated shapes VANADIS 1 should be tempered at high temperatures, above C (93 F). Relative comparison of Uddeholm cold work tool steel MATERIAL PROPERTIES AND RESISTANCE TO FAILURE MECHANISMS Grade Hardness/ Resistance to plastic deformation Grindability Machinability Dimensional stability Abrasive wear Resistance to Adhesive wear Ductility/ chipping Toughness/ gross cracking Uddeholm: CALMAX SVERKER VANADIS 4 VANADIS 6 VANADIS 1 VANADIS 23 VANADIS 3 VANADIS AISI: AISI M2 M2 This information is based on our present state of knowledge and is intended to provide general notes on our products and their uses. It should not therefore be construed as a warranty of specific properties of the products described or a warranty for fitness for a particular purpose. 7