RWL34 is a sintered steel based on ATS34 steel. The ATS34 was originally developed in Japan by Kobe Steel to make ball bearings. The internationally known cutler Robert W. Loveless was the first to use Japanese steel in cutlery due to its remarkable properties. Damasteel has improved the properties of ATS34 steel through sintering thus obtaining a very high level of purity.
The sintered variant has taken on the name of the cutler Loveless (abbreviation RWL). Unhardened (soft annealed) for ease of machining. Hardenable up to 64 HRC.
Properties of steel
- Stainless
- Long lasting
- High purity - resulting in a homogeneous microstructure and good sharpenability
- High toughness - extremely insensitive to tensile, torsion and impact loads
- Easy to work with
- Easy to polish
Hot operating temperature 1050-1160 °C (1920-2120 F)
Compared to low-alloy steels, martensitic stainless steels have a higher and almost double the resistance to deformation. Hand forging can therefore only be done on relatively small sizes. Melting begins at 1220°C (2230 F), which means the material is very sensitive to overheating. Good control of the heating temperature is required. An electric or gas oven is recommended.
Long soak times above 850°C (1560 F) lead to decarburization and scale formation.
After the hot working process, slow cooling is recommended due to the risk of cracking when the material phase transforms to martensite at approximately 200 °C (390 F). The use of vermiculite or other thermal insulating material is recommended.
Thermotherapy
Because of the risk of cracking, there is no need to grind, cut or heat work until the material is cracked. The recommendation is to have the material fully annealed by transforming which means one hour at 900°C (1650F), then cool to 750°C (1380F) for one hour and finally hold at 750°C for four hours . All martensitic material supplied by Damasteel is soft annealed at 230 - 280 HV
(20 - 28 HRC).
Cold work
Martensitic stainless steel does not work cold as easily as conventional austenitic stainless steels, but it can be formed and fabricated by a full range of cold working operations. The ductility of cold working is good, and any cold working process will increase the strength and hardness of the material.
Welding
When cooling martensitic stainless steel after any hot process, transformation of the martensitic phase occurs at around 200°C and can lead to cracking. This can be avoided by preheating the part or doing a post-weld heat treatment.
Our RWL34TMM can be welded with a full range of conventional welding methods.
Machining
As with conventional austenitic stainless steels, martensitic steels have some specific machinability properties. Martensitic stainless steels are generally easier to machine than other types of stainless steel. The machining characteristics for our martensitic stainless steel RWL34
- Low tensile strength but strong work hardening
- Trends for material buildup at the tool edge
- Hard, stringy chips can be prevented by using curler tools
Grinding and polishing
The normal grinding and polishing procedures for austenitic stainless steel can also be used for martensitic stainless steel.
Recommendation of grinding wheel:
Silicon carbide, 46 grit, soft, open density, ceramic bonded. (C46J6V)
- Velocity: 35m/sec
- Power: 0.01-0.05mm/stroke
The speed of the piece can be 1/6th of the grinding speed.
Curing:
For knife applications, the following heat treatments can be recommended for a 3.2 mm thick piece.
| Curing temperature (A) |
Tempra temperature (T) |
Tempra temperature (T) |
Hardness | |
| I | 1050 °C 1920 F | 220C 430F | 2 h | 59 HRC |
| II | 1050 °C 1920 F | 175C 345F | 2 h | 62 HRC |
| III | 1080 °C 1980 F | 220C 430F | 2 h | 58HRC |
| IV | 1050 °C 1920 F | 175 °C 345 F | 2 h | 63 HRC |
| V | 1100 °C 2010 F | 175 °C 345 F | 2 h | 64 HRC |
Suggested IV and V heat treatment processes include deep freeze (DF) at -80°C (-110 F).
To ensure that the best anticorrosive properties are achieved, we recommend a low tempering temperature.< /p>
The following time-temperature curve can serve as a guide.
A - Austenitization. Residence time 8 min on a 3.2 mm thick piece. Increase or decrease that participation time with one minute per half mm of thickness.
Q - Rapid cooling to room temperature. We suggest that you quench in oil and that the piece reaches room temperature within two minutes. Apply some pressure to the piece if it cools in air so it will not bend due to uneven cooling
DF - Freezing is not necessary but completes the transformation of the martensite and increases hardness. Hold for approx. an hour and a half
T - Temper. Waiting time two hours