Ten years ago, our company has researched and developed high-chromium iron Ω101A, which is similar to Germany No.043 and really has boomed in plastic modification market, it almost has become a standard configuration product for the twin screw extruder barrel in China these tears. With higher proportion of strengthening agent and filler to be added to the plastic raw materials, wear contradiction has become more and more prominent, the wear resistance of high-chromium iron Ω101A manifestations of powerless,to develop a higher wear resistance alloy as the new internal oval liner has become a top priority, that was when our researchers thought of element "vanadium" and "tungsten".
It is well known in the material industry, if steel is a "tiger", then the vanadium is wings, steel with vanadium, like a tiger which has got wings. Only a few percent of vanadium into the steel, Its flexibility, its hardness and its strength will be increased, wear resistance and burst resistance will be excellent, it will result in good hot temperature and bitterly cold resistance. Thanks to this feature of element vanadium, the military is willing to make the armor-piercing shell with vanadium steel, because it can even shoot through 40cm thick steel plate. We know that the vanadium is a strong carbide forming elements, and the adhesion strength with the carbon is extremely strong, it will result in forming a stable vanadium carbide “VC”. VC is one kind of typical high melting point, high hardness, and high dispersity carbide, therefore it is the element to improve the material wear characteristics massively. Regardless of separating out in the process of tempering, or VC particles formed at other stages, are all tiny dispersion state, the VC carbide particle dispersion is the main cause of the secondary hardening of metal material. Not only the fine hard phase vanadium carbide has excellent wear resistance, but also it should be mentioned that it has a better corrosion resistance, it has ability against alkaline erosion of freshwater and seawater (Its ability against the gas-salt-water corrosion resistance are better than most of the stainless steel), also be able to against all kinds of inoxidized acid except hydrofluoric acid, such as the hydrochloric acid and dilute sulphuric acid, therefore its very suitable for some certain working condition of twin screw extruders.
Thus, we boldly researched and developed superhard high wear resistance of high-vanadium iron material to apply into the manufacture of oval liner, that we now have one more material Ω102A which is hot welcomed in the market.
Why we didn’t chose the element ‘tungsten”? Because it will significantly reduce the thermal conductivity of steel, we all know that this is a taboo for an extrusion machine.Below table shows the major chemical and hardness of our R&D superhard high-vanadium iron Ω102A:
Comparing the features of material Ω102A with same as the high-vanadium alloy material No.099.3 of German W&P which specially for the oval liner, the result is the same. Because a quite expensive vanadium occupies a high proportion in material Ω102, which bring up the superhard and high wear resistance. Under the same “friction pair” and the same gravity of small sample, Shanghai Material Research Institute(SMRI) made a wear resistance test of comparing with high-vanadium material Ω102A and D2, M2, Ω 101..., we found out its “wear losses” are at least three times less than the HSS M2 (Chinese brand W6Mo5Cr4V2) , twice less than the high-chromium iron Ω101, that means the theoretical service life of Ω102A is three times longer than M2 and twice longer than Ω101A.
From the table we can see that the chemical elements containing are extremely close, the difference is that the WR5 material oval liner of Metro are adopted powder metallurgy Hot Isostatic Pressing (HIP) technology, hence the Metro company has pretty high quantity demanding of the twin hole shape with specific size in one order, such as one ton at least, as well as the delivery time of 60 days, thus the cost are quite expensive. while our Ω102A oval liner of common specification is made by a precision casting, it has no quantity demand for one order, with short delivery time and rather lower cost. What we need to point out is we certainly have the ability to use the same PM-HIP technology to make the Ω102A oval liner, and also we can provide the Ω102A oval liner which is with densifying threatment in the HIP furnace, but with the same limitations in delivery and quantity as above WR5 material from Metro Company.
We know that the service life of any mechanical parts, in addition to depends on the material elements of the composition and its heat treatment method, also depends on the material compactness, namely its density. There is no doubt that after HIP process, workpiece density is much higher than the general precision casting, its service life is much longer. But if we make a comparison between its cost, we will found oval liners with the same specifications, powder tool steel WR5 manufacturing cost is round 8 times higher than the high precision casting High-vanadium iron Ω102A. So compared with the cost-performance and the delivery, our oval liners made from Ω102A precision casting materials has an excellent advantages, no any doubt.
Because of the content of chromium in Ω101A is far higher than Ω102 A, so the corrosion resistance of high-vanadium iron Ω102A is worse than high-chromium cast iron Ω101A.