The 904L stainless steel number is 00cr20ni25m02.5cu, which is a highly alloyed super-austenitic stainless steel with low carbon content. In dilute sulphuric acid, there is a good corrosion resistance, and the addition of copper makes it very resistant to acid, designed for harsh conditions. So this kind of stainless steel is used mainly for the manufacture of corrosion resistant pressure vessels. The elements of 904L are mainly composed of elements such as Cr and Ni, which are difficult to process, and the machining is poor, and the main reasons are as follows.
1) 904L stainless steel is more powerful than other kinds of stainless steel. Because 904 l although not high hardness (70 ~ 90 HRB), but has good plasticity and elongation of 40% or higher, a reduction of 50% or more, the tensile strength at б b p 490 mpa, yield strength at 0.2 or greater б 216 mpa, and large plastic deformation in the process of cutting, the cutting force increases.
2) the thermal conductivity is low. Thermal conductivity of 904 l stainless steel (20 ℃) is 12.9 W/(m K), low thermal conductivity, only a quarter of the 45 steel (45 steel thermal conductivity is 47.5 W/(m K)). Thermal conductivity is one of the main factors influencing the cutting heat conduction, the lower the thermal conductivity of the material processed, heat was taken away by the chip and workpiece is less, while the accumulation of heat on the cutting tool, the tool wear easily.
3) it is easy to be a cross product. Due to the 904 l stainless steel toughness is big, so in the process of cutting and cutting tool materials, strong affinity, when cutting tool rake face and chip of the underlying strong friction in metal, under the action of high temperature and high pressure will produce adhesion phenomenon, generate the devolop tumor, is not easy to obtain high surface roughness requirements of machining surface.
4) shavings are not easy to bend and break. 904L stainless steel has a high elongation rate, so it is not easy to bend and break in the cutting process. If appropriate measures are not taken, it will affect the normal process of the cutting process and can easily scratch the surface and even cause the cutter to collapse and damage.
Due to the above characteristics of 904 l stainless steel, with conventional cutting tools and the traditional method of cutting, even select a very small cutting parameter, cutting tool is still easy to wear and tear, low machining efficiency, and it is difficult to achieve pattern required by the surface roughness of workpiece and machining accuracy.
Source: China 904L Flanges Manufacturer - Yaang Pipe Industry Co., Limited (www.yaang.com)