PM High Speed Steel Grades and Their Chemical Composition
Powder metallurgy high speed steel is made by atomising the melt into powder and consolidating it, so the carbides it carries are fine and evenly spread instead of coarse and banded. The table below lists the PM grades that turn up most often in tool room and purchasing documents and the chemical composition each one is made to.
What the powder route changes
A conventional high speed steel is cast into an ingot, and the carbides that form as the ingot solidifies are coarse and sit in bands. Powder metallurgy takes a different route. The melt is atomised into powder and the powder is consolidated, so an alloy of the same analysis ends up with carbides only a few micrometres across, spread evenly through the matrix instead of gathered in bands. The practical results are better grindability and better toughness at the same hardness, and a narrower spread in tool life from one batch of steel to the next.
That is why the compositions below look familiar. CPM M2 and CPM M42 carry the analysis of the conventional M2 and M42 high speed steels, and the difference the buyer pays for is the carbide size rather than a different alloy. The ABM grades sold under the ASP name and the HAP grades follow the same logic, with higher carbon and vanadium in the grades meant for the hardest cutting work.
Grades and chemical composition
The table gathers the PM grades that appear most often in tool room drawings and in purchasing documents, grouped by the country whose mills developed them. A dash marks a cell the source leaves empty.
Chemical composition of PM high speed steel grades, mass percent
| Grade | Country | C | Cr | Mo | W | Co | V | Nb |
|---|---|---|---|---|---|---|---|---|
| ASP2017 | France | 0.8 | 4.2 | 3 | 3 | 8 | 1 | 1 |
| ASP2023 | France | 1.28 | 4.2 | 5 | 6.4 | — | 3.1 | 1 |
| ASP2030 | France | 1.28 | 4.2 | 5 | 6.4 | 8.5 | 3.1 | 1 |
| ASP2053 | France | 2.45 | 4.2 | 3.1 | 4.2 | — | 8 | 1 |
| ASP2060 | France | 2.3 | 4.2 | 7 | 6.5 | 10.5 | 6.5 | 1 |
| CPM M2 | United States | 0.9 | 4.2 | 5 | 6.4 | — | 2 | — |
| CPM M42 | United States | 1.1 | 3.8 | 9.5 | 1.5 | 8 | 1.2 | — |
| HAP10 | Japan | 1.3 | 4 | 6 | 3 | — | 4 | — |
| HAP20 | Japan | 1.5 | 4 | 7 | 2 | 5 | 4 | — |
| HAP40 | Japan | 1.3 | 4 | 5 | 6.5 | 8 | 3 | — |
| HAP50 | Japan | 1.5 | 4 | 6 | 8 | 8 | 4.5 | — |
| HAP70 | Japan | 1.9 | 4 | 10 | 12 | 12 | 4.5 | — |
| HAP72 | Japan | 1.9 | 4 | 8 | 10 | 10 | 5 | — |
| FT15 | China | 1.5 | 4 | <1 | 12 | 5 | 5 | — |
| FR71 | China | 1.2 | 4 | 5 | 10 | 12 | 2 | — |
| GF1 | China | 0.85 | 4 | — | 18 | — | 1 | — |
| GF2 | China | 1.1 | 4 | 5 | 6 | — | 2 | — |
| GF3 | China | 1.5 | 4 | 5 | 10 | 9 | 3 | — |
Source, 刀具材料速查手册, Table 2-21, Domestic and foreign PM high speed steel grades and their chemical composition, printed page 33. All values are mass percent. Every figure was read from a rendered image of the printed page and checked row by row. This is a reference summary of published practice and not an Aobo Steel specification.
Table notes. The grades are grouped by the country whose mills developed them, in the order the source prints them, and the niobium figure is printed once for each group. A dash is a cell the source leaves empty, which in the cobalt column marks a cobalt free grade. The chromium figure for ASP2017 is printed as 4.2 in the source and as 4.0 in the maker’s own data sheet; both readings are of the same nominal analysis. Nominal analyses vary by maker and by revision, so confirm the cast analysis on the mill certificate before a grade is written into a purchase specification.
Reading the composition columns
Carbon sits between 0.8 and 2.45 percent across the table and it is the first number to read, because it sets the volume of carbide the steel can form and therefore the ceiling on hardness. The cobalt free grades are the ones in the middle of that range, and the grades taken above 2 percent carbon are the ones sold for the most abrasive cutting work.
Vanadium is the column that separates a general purpose PM grade from a wear grade. It runs from 1 percent in ASP2017 to 8 percent in ASP2053, and the higher it goes the harder the steel becomes to grind, which is the trade the powder route was invented to soften. Tungsten and molybdenum both form the hard carbides and are read together, since a grade that is high in one is usually low in the other.
Cobalt raises hot hardness, which is why it appears at 8 to 12 percent in the grades used on high speed cutting of tough materials and is empty in the grades sold for cold work and for plastic moulds. Niobium appears once in the table, at 1 percent in the ASP group, where it is added to control grain growth during consolidation.
Related reference data
CPM M2 and CPM M42 hold the analysis of the conventional grades supplied as M2 tool steel and M42 tool steel. The composition ranges of the conventional grades these PM steels are measured against are listed on the tool steel composition chart, and the microstructural difference between the two routes is set out in PM versus conventional tool steel.
Compiled from 刀具材料速查手册, Table 2-21 on printed page 33. Every figure was read from a rendered image of the printed page and checked row by row. The table is a reference summary of published practice rather than an Aobo Steel specification, so confirm the cast analysis on the mill certificate before the data is written into a process sheet.