What is a scraper blade made of?
Tungsten carbide is a compound made of 50% tungsten and 50% carbon. There are several methods used to form the compound, the most common is by reacting tungsten metal with carbon at a temperature between 1400-2000 degrees Celsius.
High Speed Steel
High speed steel (HSS) is an alloy that combines steel (iron and carbon) with other elements such as chromium, molybdenum, tungsten, vanadium or cobalt. Elements other than steel can account for as much as 20% of the make up of HSS, but always exceed 7%.
The addition of these elements to steel alone does not create HSS, the material has to heat treated and tempered as well.
High Speed Steel (HSS) is capable of cutting material quicker than high carbon steel, hence the "high-speed". This is due to its greater hardness and abrasion-resistance when compared to high carbon and other tool steels.
Why are HSS and carbide used to make scraper blades?
A scraper blade needs to be made of a harder material than the object it is scraping for it to be effective. The additional alloying elements and manufacturing processes such as heat treating that HSS undergoes give it the hardness required for scraping.
Carbide scraper blades are harder than HSS. This allows them to be used on an even greater range of materials.
Non replaceable scraper blades
Non-replaceable scraper blades are nearly always made of HSS, as the cost of making the entire blade and shaft from carbide would be too great.
Whilst non-replaceable scraper blades are made of HSS, only a small section at the end of the scraper will have been heat treated and tempered. The section that has been heat treated and tempered is often a different colour to the rest of the shaft.
What materials can scraper blades be used on?
HSS blades cost less than carbide ones, but will require sharpening more often.
Carbide blades can last ten times as long as HSS before they need sharpening, but when they do, they require a diamond disc grinding wheel to sharpen them, unlike HSS. This makes HSS more popular for scraping jobs away from the workshop, where you may not have access to a diamond grinding wheel.