SUM22 is a free cutting structural steel, free cutting steel is easy to be (turning, milling, pulling, planing, drilling, etc.) cutting steel, also called automatic machine tool processing steel, short for automatic steel.
It is to adapt to the automation of mechanical processing and flow line production. This kind of steel can use high cutting speed and deep turning machining, and since joining the free-cutting steel elements make cutting resistance decreases and the join of the element itself characteristics and formation of the compound ACTS as lubricate cutter blade, make the chip easy broken, reduce the wear and tear, thus improve the roughness and precision of the processed parts, improves the knives’ service life and production efficiency.
Precipitation, which plays a role of lubrication to improve the cutting performance of steel, make the steel chips finely, reduce tool wear, and ultimately extend tool life. Compared with lead-free steel, the cutting performance of lead-containing steel can be increased by 20-50%, while the mechanical properties and heat treatment performance remain basically unchanged, and it has no effect on cold and hot workability and weldability. Lead free-cutting steel has been widely used as important parts for the manufacture of precision instrument parts, auto parts, and various types of machinery.
However, lead free-cutting steel has low contact fatigue, so it is not suitable for parts such as gears and bearings that bear large fatigue stress loads. SUM22 has a tendency to be replaced by it. Its cutting performance is also very good. It is suitable for more strict occasions where SUM22 cannot be used.
SUM22 is an S-P composite high-sulfur, low-silicon free-cutting steel. The machinability is significantly higher than that of Y12Pb , and the production efficiency is 30-50% higher than that of Y12Pb steel. Especially when tapping, the tap life is more than twice that of Y12Pb. SUM22 is often used in the manufacture of unimportant standard parts, such as bolts, nuts, and pipes. Connectors, spring seats, etc.
SUM22 is produced to adapt to mechanical processing automation and assembly line production. This type of steel can be cut with a higher cutting speed and a deeper amount of cutting, and the cutting resistance is reduced due to the addition of free-cutting elements in the steel, and the characteristics of the added elements and the compounds formed to lubricate the cutting edge The function of the part makes the chips easy to break and reduces wear.
SUM22 Chemical Composition:
C: 0.13 max
SUM22 Mechanical Properties:
1. Tensile strength σb (MPa):
(Hot rolled) 390～540;
(Cold drawn) Steel thickness or diameter:
- 8～20: 530～755;
- >20～30: 510～735;
2. Elongation δ5 (%): (hot rolled)≥22; (cold rolled)≥7.0
3. Reduction of area ψ (%): (hot rolled) ≥ 36
4. Hardness: (hot rolled)≤170HB; (cold drawn)152～217HB
The machinability of SUM22 is significantly higher than that of Y12, and the production efficiency is 30-50% higher than that of Y12 steel. Especially when tapping, the tap life is more than twice that of Y12. SUM22 is often used in the manufacture of unimportant standard parts, such as bolts and nuts. , Pipe joints, spring seats, etc.