Datasheet VP420IM

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<p>PLASTIC MOULD STEEL VP420IM</p><p>BB iiee DDeesscc iipp iioonn rr ff rr tt</p><p>ii</p><p>VP420IM is a martensitic stainless steel indicated</p><p>for manufacturing of plastic moulds. It is produced</p><p>with special procedures, including vacuum degassing</p><p>and also refining by ESR (“Electro-Slag-Remelting”),</p><p>leading to high homogeneity of properties. When</p><p>applied in plastic moulds, VP420IM presents the</p><p>following properties:</p><p>- High corrosion resistance</p><p>- Excellent polishability.</p><p>- Good wear resistance.</p><p>- Good machinability.</p><p>- High mechanical strength, leading to hardness</p><p>up to 52 HRC.</p><p>CChheemmiiccaall CCoommppooss ttiioonn</p><p>CC SSii MMnn CCrr VV</p><p>0.40 0.80 Max.</p><p>1.00 13.50 0.25</p><p>SSttaannddaarrdd SSppeecc iiccaatt oonnss iiff ii</p><p>rr ii</p><p>VP420IM corresponds to DIN X 42 Cr 13, WNr.</p><p>1.2083, and is a modified AISI 420 grade.</p><p>PPhhyyssiiccaall PPrrooppee tt eess</p><p>Density at 20 ºC: 7.7 kg/dm3.</p><p>Thermal conductivity at 100 ºC: 23.0 W/m.K.</p><p>DDeelliivveerryy CCoonnddiittiioonnss</p><p>Standard Identification colors:</p><p>blue – brown.</p><p>Forms and hardness: annealed with 200 HB max.</p><p>VP420IM is available in the following sizes:</p><p>Round: max. 560 mm.</p><p>Square: max. 500 mm.</p><p>Flat: maximum area of 3100 cm2.</p><p>Other dimensions under consultation.</p><p>iiTTyyppiiccaall AApppplliiccaatt oonnss</p><p>VP420IM is applied in moulds which work in</p><p>corrosion conditions or need to be stainless for other</p><p>reasons. Typical applications are:</p><p>Moulds for Injection or extrusion of chlorinated</p><p>thermoplastic polymers, such as PVC.</p><p>Moulds that work or are storage in corrosion</p><p>environments or wet conditions.</p><p>Moulds for glass industry.</p><p>Other applications were high mechanical</p><p>strength and high corrosion resistance are</p><p>necessary.</p><p>PPrroocceessssiinngg ooppeerraattiioonnss</p><p>The following processes can be applied for</p><p>producing moulds with VP420IM:</p><p>- Machining: turning, milling or grinding. The</p><p>parameters should be adequate for machining</p><p>of martensitic stainless steels. Note that</p><p>VP420IM is magnetic, either in annealed or in</p><p>hardened condition.</p><p>- Electrical discharge machining: the white layer</p><p>should be mechanically removed, by grinding or</p><p>sanding. It is also important to re-temper the</p><p>moulds in a temperature 50 ºC lower than that</p><p>of the previous tempering.</p><p>- Polishing: VP420IM can be polished in the usual</p><p>techniques, presenting excellent polishability</p><p>due to its high microstructural cleanness. For</p><p>improving polishing, a proper heat treatment</p><p>must be applied, being important the absence of</p><p>carburization or decarburization.</p><p>PLASTIC MOULD STEEL VP420IM</p><p>H tt ttHeeaatt rreeaattmmeenn</p><p>Annealing: soft annealing should be carried out by</p><p>slow heating (100 ºC/h) to 780/840 ºC for 1 hour</p><p>(after soaking), followed by slow cooling at 30 ºC per</p><p>hour to 600 ºC and, then, by air cooling.</p><p>Stress relieving: Intense material removal during</p><p>machining of moulds can induce considerable stress.</p><p>A stress reliving treatment is important to remove of</p><p>such stresses, in order to avoid distortions, being</p><p>applied after machining and before heat treatment.</p><p>The indicated procedure is slow heating (100 ºC/h) to</p><p>~ 650 ºC, holding until complete homogenisation</p><p>(normally 30 min for 25 mm of the larger section, with</p><p>minimum of 2 hours), and slow furnace cooling at</p><p>least down to 100 ºC.</p><p>Hardening and Tempering: the recommended</p><p>hardening and tempering temperatures are:</p><p>Pre-heating Hardening Tempering*</p><p>400 - 450 ºC 1000 - 1040 ºC</p><p>(usually 1025)</p><p>175 – 550 ºC</p><p>(see diagram)</p><p>* For providing maximum corrosion resistance, tempering</p><p>temperatures should be between 200-300 ºC (see diagram on</p><p>the right), for hardness between 48-54 HRC.</p><p>After preheating, moulds must be slow heated</p><p>(300 ºC/h max.) to hardening temperature, holding 30</p><p>min after soaking (i. e. after mould is fully heated</p><p>throughout). Surface decarburization cause decrease</p><p>in hardness and may cause polishing problems</p><p>named “overpolishing”. Therefore, the use of</p><p>protective atmosphere (or vacuum) is important</p><p>during heating to hardening.</p><p>Quenching may be done in oil, holding until</p><p>reaching 80 ºC. Then, it is recommended that moulds</p><p>are carried to another furnace at 100/150 ºC in order</p><p>to equalise temperature (in this step 1h for each 100</p><p>mm is required). Immediately after this treatment,</p><p>heating to tempering should start.</p><p>Tempering temperatures should be suitable to the</p><p>required hardness (see diagram). Double tempering</p><p>is required and after each one moulds must cool</p><p>down to room temperature. For each tempering</p><p>treatments, the holding time of at least 2 h (after</p><p>soaking) is necessary. As discussed before,</p><p>tempering between 200 - 300 ºC is recommended to</p><p>improve corrosion resistance.</p><p>Case hardening and nitriding: these treatments</p><p>impair corrosion resistance and are not normally</p><p>applied.</p><p>tt rr ff</p><p>iill rr tt ii</p><p>RReellaa iivvee CCoommppaa iissoonn oo</p><p>VV llaa eess MMee aallss PPllaasstt cc MMoouulldd SStteeeellss</p><p>VP20 ISO</p><p>VP20 ISO-F</p><p>VP20 ISO-FS</p><p>VP20 IM</p><p>VP50 IM</p><p>VH13 IM</p><p>VP80</p><p>VP420 IM</p><p>VP440 IM</p><p>VTM IM</p><p>SINTER 23</p><p>Machinability Polishability</p><p>Wear</p><p>resistance</p><p>Dimentional</p><p>Stability</p><p>Corrosion</p><p>Resistance</p><p>M</p><p>as</p><p>s l</p><p>os</p><p>s (</p><p>m</p><p>g/</p><p>cm</p><p>2 )</p><p>Tempering Temperature</p><p>(Corrosion test in nitric acid)</p><p>Corrosion Resistance</p><p>Hardening Temp. = 1025 ºC</p><p>Oil Quenching</p><p>H</p><p>ar</p><p>dn</p><p>es</p><p>s (</p><p>H</p><p>R</p><p>C</p><p>)</p><p>Tempering Temperature (ºC)</p><p>Results for small samples with 20 x 20 x 20 mm 3</p><p>Note: All information presented are intended to provide guidelines of material use. They do not have relation to warranty of specific properties or contractual</p><p>obligations</p><p>Brief Description</p><p>Chemical Composition</p><p>C</p><p>Standard Specifications</p><p>Delivery Conditions</p><p>Typical Applications</p><p>Heat treatment</p><p>Relative Comparison of �Villares Metals Plastic Mould Steels</p>