Damasteel Martensitic Damascus Steel

PRODUCT INFORMATON Hardenable Stainless Damascene Steel, 93x.x

MARTENSITIC STAINLESS DAMASCENE STEEL Damasteels martensitic stainless Damascene Steel is a mix of two stainless steels RWL 34 and PMC27 both of which are variations of 420 martensitic stainless steel family with a minimum 13 percent chromium content. These alloys may be considered for a wide variety of applications where one or more of the following properties are important:

High hardness after hardening and tempering Resistance to corrosion Easy of grinding and polishing

Each alloy represents a good combination of corrosion resistance and hardenability. This combination of properties is the reason for its use in the cutlery industry. Some examples of their uses are in knifes, flatware cutlery, jewellery, and other applications where corrosion resistance and hardness are important. For more information please see reference 1.

Chemical composition of Damasteel 93x,x (weight-%) of the two different alloy used.

Grade Etch Colour

C Si Mn Cr Mo V

I. RWL 34 Bright 1.05 0.50 0.50 14 4 0.2

II. PMC27 Dark 0.60 0.50 0.50 18 - -

Mechanical Properties Annealed Material (bar and plate), minimum values at 20C of 93x,x in the soft annealed condition

Steel Grade Proof Strength Rp0.2 MPa

Tensile Strength Rm

MPa

Elongation A5 %

Impact Value Kv

J

93x,X 270 Max 700 45 60

Damasteel AB www.damasteel.com Stallgatan 9 [email protected] 815 76 Sderfors +46 293 306 00

PRODUCT INFORMATON Hardenable Stainless Damascene Steel, 93x.x Physical Properties

The physical properties for RWL-34 and PMC27 are nearly the same. However, there is a minor difference in the density between the two grades. Date according to EN 10088.

Density Kg/dm3 7.7 to 7.8 Modulus of elasticity GPa 200 Poissons 0.3 Thermal conductivity W/mC 15 Heat capacity J/kgC 460 Electrical resistivity m 0.73

Corrosion Resistance The martensitic stainless steels have a moderate to good corrosion resistance and are therefore suitable for a wide range of applications. The inclusion of molybdenum in RWL-34 as one of the grades makes a damascene steel with a higher corrosion resistance. For a more detailed description of their corrosion resistance properties please refer to Sandvik Steel Corrosion Handbook, see ref 1.

Fabrication

Hot working

The hot working temperature range is between 1,150 to 1,160C (1,920 2,120F) when compared to normal low alloy carbon steels, stainless steel has higher, almost doubled deformation stresses. Hand forging must therefore be performed on relatively small dimensions. Melting starts at 1,220C which means that the material is sensitive to overheating. A good control of the heating temperature is needed. An electric or gas fired furnace is recommended.

Long soaking times at temperatures above 850C (1580F) leads to scale formation. Slow cooling after the hot working prevents crack formation at the martensitic formation temperature of 200C (400F). Slow cooling using vermiculite or other heat insulating materials is recommended.


PRODUCT INFORMATON Hardenable Stainless Damascene Steel, 93x.x Heat treatment Because of the risk of cracking, no grinding, cutting or machining should be done after hot working until the material is annealed. The material should be annealed for 5 hours at 750 - 780 C (1380 - 1440F). All martensitic material supplied from Damasteel is soft annealed to 250 300HV.

Hardening For knife applications the following heat treatments can be recommended:

Hardening Temperature

(A)

Tempering Temperature

(T)

Tempering Time

Hardness RWL-34

(HRC) PMC27

1 1,050C (1,920F) 220C (430F) 2 h 59 53 2 1,050C (1,920F) 175C (345F) 2 h 62 54 3 1,080C (1,980F) 220C (430F) 2 h 58 56 4 1,050C (1,920F) 175C (345F) 2 h 63 58 5 1,100C (2,010F) 175C (345F) 2 h 64 60 The recommended heat treatment processes 4 and 5 include deep freezing (DF) at -80C (-140F). To ensure that best corrosion properties are achieved we recommend a low temperature tempering. The following time temperature curve can act as a guide, see figure 1.

Figure1: Piece Hardening of Damasteel Damascene Stainless Steel 3.2 mm Thick


PRODUCT INFORMATON Hardenable Stainless Damascene Steel, 93x.x Cold Working Martensitic stainless steel does not cold work as well as the conventional austenitic stainless steels but can be formed and fabricated by a full range of cold working operation. The cold working ductility is good and any cold working operations will increase the strength and the hardness of the material. Blanking and punching can be done but other cold working operation should be avoided.

Welding Martensitic stainless steel has the possibility of metallurgical change during cooling, which can lead to cracking. This can be avoided either by preheating or post-weld heat treatment. The grade can be welded by a full range of conventional welding methods. For best result use welding filler metals and several different companies that can supply them from stock.

Machining As with the conventional austenitic stainless steels, the martensitic steels have some specific machinability properties, but are generally easier to machine

Low tensile strength but a strong work hardening Tendencies for buildup of material on the tool edge Tough and stringy chips can be prevented by using chip curler tools

Heavier feeds and slower speeds are used for machining the austenitic materials than are used for carbon steels. This reduces the work hardening and the tool edge build-up.

For general guideline, see ref 2.

Grinding and Polishing Normal grinding and polishing procedures for austenitic stainless can be used also for the martensitic stainless steel.

Grinding wheel recommendation: Silicon Carbide, 46 grit, soft, open density, ceramic bonded. (C46J6V)

Speed: 35 m/sec Feed: 0.01-0.05 mm/stroke

Speed of the work piece may be 1/60 of the grinding speed. Damasteel AB www.damasteel.com Stallgatan 9 [email protected] 815 76 Sderfors +46 293 306 00

PRODUCT INFORMATON Hardenable Stainless Damascene Steel, 93x.x Abrasive Belt Grinding

Application Belt type Grit Speed (m/s) Lubrication Plate, Strip, Bar or Wire Rough grinding Al2O3 60-80 20-27 Grease Fine grinding 80-100 19-22 Polishing 100-320 20-27 Cutlery Fine grinding 80 28 Polishing 150-220 28

Etching Etching is done to develop the patterns on the finished piece. The best conditions for etching are good polished surfaces carefully degreased. The work piece is preferably dipped into the etching acid. After etching the piece must be carefully cleaned in water. A final cleaning with brush and soap eliminates the risk for acid dwell.

Method

Etching Acid1 Approx. time (min)

Etching RWL34

Colour PMC27

1. Water 70% H2SO4 30% Soap

5 Bright Grey

2. Water 63% H2SO4 30% HClO4 7%

5 Bright Black

3. Water 63% HCl 37%

5 Bright Black

The second method gives a heavier attack and a deeper relief, but unhealthy gases are formed. Acids must be handled with care and ensure that the work place is well ventilated. If the surfaces still have oxides from the heat treatment, pitting corrosion may occur.

1 H2SO4 Sulfuric acid HClO4 Perchloric acid HCl Hydrochloric acid Fe(III)Cl Iron(III) chloride, also called ferric chloride CU(II)Cl Copper(II) chloride Damasteel AB www.damasteel.com Stallgatan 9 [email protected] 815 76 Sderfors +46 293 306 00

PRODUCT INFORMATON Hardenable Stainless Damascene Steel, 93x.x Products Damasteel has a standard product program and the latest information can be found at www.damasteel.com. The following products can be supplied.

Hot rolled plate, sheet and strip Bar Rod Billet

Reference

1. Design guidelines for the selection and use of stainless steel, NiDi, 2002 2. Sandvik Steel Corrosion Handbook Stainless Steel, 1999 ISBN: 91-630-2124-2 3. Sandvik Coromant, Knowledge base, http://www.sandvik.coromant.com

Information given in this datasheet may be subject to alterations without notice. Care has been taken to ensure that the contents of this publication are accurate but Damasteel and its affiliated companies to not accept responsibility for errors or for information which is found to be misleading. Suggestions for or descriptions of the end use or application of products or methods of working are for information only and Damasteel and its affiliated companies accept no liability in respect thereof. Before using products supplied or manufactured by the company the customer should satisfy themselves of their suitability.


MARTENSITIC STAINLESS DAMASCENE STEELCorrosion ResistanceFabricationHot working

Heat treatmentHardeningCold WorkingWeldingMachiningGrinding and PolishingEtchingProducts

Documents

Damasteel Martensitic Damascus Steel