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Quality begins with quality material
Classic scissors are made of carbon steel. Modern manufacturing techniques include stainless steel. Some stainless steel alloys are good for cutlery. They can be hardened to acceptable levels and maintain toughness. Stainless Steel performs best when they are forged.
However, cold-forged scissors are of very poor quality and include the cheap scissors sold on the market in large quantities. They are made of steel wire which has been cut to length and placed under high pressure without heating, and are mostly only held together with a simple rivet.
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We neither manufacture nor offer scissors of this type. More than 90% of our scissors are fabricated from sheets or strips of non-corrosive material cut out with a fine blanking technique and properly hardened. The some of our special scissors, such as those made for cutting Kevlar material are made from high carbon alloy steel. In some cases, special alloys with a higher proportion of molybdenum or vanadium used. Molybdenum adds toughness and increased corrosion resistance to withstand industrial chemicals and solvents and inhibits pitting caused by chlorides. Vanadium adds toughness and fatigue resistance.
The stainless material used is of SUS 420J2. This alloy is rustproof, nickel-free, and can be well hardened (hardness 52-54 Rockwell). Nusharp is mainly offering these rustproof scissors with plastic handles that are ergonomically designed.
Nusharp uses only the finest material in our own scissors. We import material only from Japanese and German companies, e.g. Hitachi, Aichi, Nisshin, and Bohler. To fulfill different application and market requirement, we also use DIN 1.4034, 440A, 440C, AUS8, DIN 1.4528.
Stainless Steel
When you add a certain amount of Chromium to the steel, the steel becomes corrosion resistant. Steel alloys to which a minimum of 11.5% Chromium has been added do not usually form red rusts and so are called "stainless". The Chromium, when in contact with air, forms a non-reactive Chromium Oxide film. This passive film protects the surface iron from reacting with oxygen and forming rust. If the surface is scratched, the newly exposed chromium again reacts with the oxygen to form a new film barrier!
The passive chromium oxide film, which may be as thin as a molecule in thickness, can lose its protectiveness in reducing environments such as hydrochloric acids, etc. Increasing the Chromium content of the stainless steel increases its protective qualities. Adding Molybdenum also greatly expands the range of environments which are sufficiently oxidizing to maintain a passive film. This means that Molybdenum helps certain environments react easier with the Chromium to oxidize.
The only detriment of Chromium is that it does not harden the iron. Unfortunately, the Chromium must be added in great quantities, because the main hardening agent in steel, Carbon, can react with up to 17 times its own weight of Chromium to form Carbides. Carbides do not resist corrosion. So one needs at least an 18 to 1 ratio of Chromium to Carbon to have enough free Chromium left over after the reaction, to give the steel its stainless properties! Martensitic stainless steels are limited to 12-18% chromium. Only at this range can a fully Austenitic structure be obtained in the heat treating process. As with Carbon and alloy steels, 100% Austenite is required prior to quenching, if full-hardening response is to be obtained.
SUS 420J2 it's Carbon content is 0.26 ~ 0.40%. After hardening, its hardness is around 52 ~ 55 HRC. Because of its properties such as machinability or ease of forming and buffing, it is good for mass production of shearing and cutting tool. DIN 1.4034 is with 0.43 ~ 0.50% Carbon to increase hardness; DIN 1.4116 is with 0.42 ~ 0.48% Carbon, 13.8 ~ 15.0% Chrome, 0.45 ~0.60% Molybdenum, 0.10~0.15% Vanadium to add toughness, fatigue resistance and density. SUS 440 series with suffix A, B, C, F after hardening, the hardness of 440A is 54HRC, 440B is 56HRC, and 440C is 58HRC. 440C is, with 16 ~ 18% Chrome, first used on surgery tool and marine vessel. 440C, with its excellent properties of corrosion resistance, durability and toughness, is widely used on high quality knife.
AUS8 it's developed by Aichi, Japan. For its excellent properties such as corrosion resistance, durability, and toughness, AUS8 is widely used on high end cutting tool. AUS8 is 0.049%Ni, 13~14.5% Cr, 0.1~0.3%Mo,0.1~0.25%V, hardness HRC 60~61 after hardening.
ATS-34 it's developed by Hitachi, equivalent to 154CM, but less expensive than 154CM. HRC is 60~61 after hardening. Its toughness and sharpness is excellent.
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