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Dievar-English.Pdf UDDEHOLM DIEVAR® UDDEHOLM DIEVAR Uddeholm Dievar is a specially developed steel grade by Uddeholm, which provides the best possible performance. The chemical composition and the very latest in production technique make the property profile outstanding. The combination of excellent toughness and very good hot strength gives Uddeholm Dievar a very good heat checking- and gross cracking resistance. The steel is suitable in high demand hot work applications like die casting, forging and extrusion. The property profile makes it also suitable in other applications, e.g. plastics and High Performance Steel. Uddeholm Dievar offers the potential for significant improvements in die life, thereby improving the tooling economy. 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. Classified according to EU Directive 1999/45/EC For further information see our “Material Safety Data Sheets”. Edition 9, 06.2015 The latest revised edition of this brochure is the English version, which is always published on our web site www.uddeholm.com SS-EN ISO 9001 SS-EN ISO 14001 UDDEHOLM DIEVAR General Hot work applications Uddeholm Dievar is a high performance Heat checking is one of the most common chromium-molybdenum-vanadium alloyed hot failure mechanism e.g. in die casting and now work tool steel which offers a very good days also in forging applications. Uddeholm resistance to heat checking, gross cracking, hot Dievar’s superior ductility yields the highest wear and plastic deformation. Uddeholm possible level of heat checking resistance. Dievar is characterized by: With Uddeholm Dievar’s outstanding tough- •Excellent toughness and ductility in all ness and hardenability the resistance to heat directions checking can further be improved. If gross •Good temper resistance cracking is not a factor then a higher working •Good high-temperature strength hardness can be utilized (+2 HRC). •Excellent hardenability Regardless of the dominant failure mecha- nism; e.g. heat checking, gross cracking, hot •Good dimensional stability throughout heat wear or plastic deformation. Uddeholm Dievar treatment and coating operations offers the potential for significant improve- ments in die life and then resulting in better Typical C Si Mn Cr Mo V analysis % 0.35 0.2 0.5 5.0 2.3 0.6 tooling economy. Standard Uddeholm Dievar is the material of choice specification None for the high demand die casting-, forging- and Delivery extrusion industries. condition Soft annealed to approx. 160 HB Colour code Yellow/grey To ols for die casting Aluminium, Improved tooling performance Part magnesium alloys Dies 44–50 HRC Uddeholm Dievar is a premium hot work tool steel developed by Uddeholm. It is manufac- tured utilizing the very latest in production and To ols for extrusion refining techniques. The Uddeholm Dievar Copper, Aluminium, development has yielded a die steel with the Part copper alloys magnesium alloys ultimate resistance to heat checking, gross HRC HRC cracking, hot wear and plastic deformation. Dies – 46–52 The unique properties profile for Uddeholm Liners, dummy Dievar makes it the best choice for die casting, blocks, stems 46–52 44–52 forging and extrusion. To ols for hot forging Part Steel, Aluminium Inserts 44–52 HRC 3 UDDEHOLM DIEVAR Properties TENSILE PROPERTIES AT ELEVATED TEMPERATURE Short transverse direction. The reported properties are representative Rm, Rp0,2 A5, Z of samples which have been taken from the ksi MPa % centre of a 610 x 203 mm (24" x 8") bar. 290 2000 100 Z Unless otherwise is indicated all specimens 261 1800 90 232 1600 80 have been hardened at 1025°C (1875°F), 203 1400 70 quenched in oil and tempered twice at 615°C 174 1200 Rm 60 (1140°F) for two hours; yielding a working 145 1000 50 40 hardness of 44–46 HRC. 116 800 Rp0,2 87 600 30 58 400 20 Physical properties 29 200 A5 10 100 200 300 400 500 600 700°C Data at room and elevated temperatures. 210 390 570 750 930 1110 1290 °F Temperature 20°C 400°C 600°C Testing temperature (68°F) (750°F) (1110°F) Density, kg/m3 7 800 7 700 7 600 Minimum average unnotched impact ductility is lbs/in3 0.281 0.277 0.274 300 J (220 ft lbs) in the short transverse Modulus of elasticity direction at 44–46 HRC. MPa 210 000 180 000 145 000 psi 30.5 x 106 26.1 x 106 21.0 x 106 Coefficient of thermal expansion CHARPY V-NOTCH IMPACT TOUGHNESS per °C from 20°C–12.7 x 10–6 13.3 x 10–6 per °F from 68°F– 7.0 x 10–6 7.3 x 10–6 AT ELEVATED TEMPERATURE Thermal Short transverse direction. conductivity Impact energy W/m °C – 31 32 Btu in/(ft2h°F) – 216 223 ft. lbs J 102 140 88 120 Mechanical properties 45 HRC 73 100 Tensile properties at room temperature, short transverse direction. 58 80 47 HRC 44 60 Hardness 44 HRC 48 HRC 52 HRC Tensile 30 40 strength 1480 MPa 1640 MPa 1900 MPa Rm 96 tsi 106 tsi 123 tsi 15 20 50 HRC 214 000 psi 237 000 psi 275 000 psi Yield 50 100 150 200 250 300 350 400 450°C strength 1210 MPa 1380 MPa 1560 MPa 120 210 300 390 480 570 660 750 840°F Rp0,2 78 tsi 89 tsi 101 tsi 175 000 psi 200 000 psi 226 000 psi Testing temperature Elongation A5 13 % 13 % 12,5 % Reduction of area Z 55 % 55 % 52 % 4 UDDEHOLM DIEVAR TEMPER RESISTANCE Stress relieving The specimens have been hardened and After rough machining the tool should be tempered to 45 HRC and then held at differ- heated through to 650°C (1200°F), holding ent temperatures from 1 to 100 hours. time 2 hours. Cool slowly to 500°C (930°F), then freely in air. Hardness, HRC 50 500°C Hardening (930°F) 45 Preheating temperature: 600–900°C (1110– 550°C (1020°F) 1650°F). Normally a minimum of two 40 preheats, the first in the 600–650°C (1110– 1200°F) range, and the second in the 820– 35 850 C (1510–1560 F) range. When three 600°C ° ° (1110°F) preheats are used the second is carried out 30 650°C at 820°C (1510°F) and the third at 900°C (1200°F) (1650°F). 25 Austenitizing temperature: 1000–1030 C (1830– 0,1 1 10 100 ° Time, h 1890°F). Temperature Soaking time* Hardness before Heat treatment— °C °F minutes tempering 1000 1830 30 52 ±2 HRC general recommendations 1025 1875 30 55 ±2 HRC * Soaking time = time at hardening temperature after the Soft annealing tool is fully heated through Protect the steel and heat through to 850°C Protect the tool against decarburization and (1560°F). Then cool in furnace at 10°C (20°F) oxidation during austenitizing. per hour to 600°C (1110°F), then freely in air. CCT GRAPH Austenitizing temperature 1025°C (1875°F). Holding time 30 minutes. °F °C 2000 1100 Austenitizing temperature 1025°C Holding time 30 min. 1800 1000 A c 1 f 900 = 890°C 1600 A c 1 s 800 Carbides = 820°C 1400 Pearlite 700 1200 Cooling Hard- 600 curve ness T800–500 No. HV 10 (sec) 1000 500 1 681 1,5 800 400 2 627 15 Bainite 3 620 280 Ms 600 300 4 592 1 248 5 566 3 205 400 200 6 488 5 200 Martensite M f 7 468 10 400 200 100 8 464 20 800 1 2 3 4 5 6 7 8 9 9 405 41 600 1 10 100 1 000 10 000 100 000 Seconds 1 10 100 1 000 Minutes 1 10 100 Hours Air cooling of 0.2 1.5 10 90 600 bars, Ø mm 5 UDDEHOLM DIEVAR HARDNESS, GRAIN SIZE AND Tempering RETAINED AUSTENITE AS FUNCTIONS OF AUSTENITIZING TEMPERATURE Choose the tempering temperature according to the hardness required by reference to the Grain tempering graph below. Temper minimum size ASTMHardness, HRC Retained austenite % three times for die casting dies and minimum 10 60 Grain size twice for forging and extrusion tools with intermediate cooling to room temperature. 8 58 Holding time at temperature minimum 2 hours. Hardness 6 56 Tempering in the range of 500–550°C (930– 1020 F) for the intended final hardness will result 54 4 ° in a lower toughness. Retained austenite 52 2 50 0 TEMPERING GRAPH 990 1000 1010 1020 1030 1040 1050 °C 1815 1830 1850 1870 1885 1905 1920 °F Hardness, HRC Retained austenite, % Austenitizing temperature 60 Austenitizing temperature 1025°C (1875°F) 55 Quenching 50 As a general rule, quench rates should be as 1000°C (1830°F) Temper rapid as possible. Accelerated quench rates are 45 embrittlement required to optimize tool properties specifi- cally with regards to toughness and resistance 40 6 to gross cracking. However, risk of excessive 35 4 distortion and cracking must be considered. Retained austenite 30 2 QUENCHING MEDIA The quenching media should be capable of 25 100 200 300 400 500 600 700°C creating a fully hardened microstructure. 210 390 570 750 930 1110 1290°F Different quench rates for Uddeholm Dievar Tempering temperature (2 + 2h) are defined by the CCT graph, page 5. RECOMMENDED QUENCHING MEDIA • High speed gas/circulating atmosphere EFFECT OF TEMPERING TEMPERATURE ON ROOM TEMPERATURE CHARPY V NOTCH •Vacuum (high speed gas with sufficient IMPACT ENERGY positive pressure).
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