Stainless steel powder metallurgy is prone to porosity when it is manufactured, which will affect its use, make its mechanical properties, corrosion resistance and abrasion resistance decline, limiting the application of stainless steel powder metallurgy. And these properties of stainless steel powder metallurgy with the increase in density and improve, so, improve the density of stainless steel powder metallurgy is from the necessary, then how to improve the density of stainless steel powder metallurgy?
First, super solid phase line sintering:
1, the traditional stainless steel sintering generally use solid phase sintering, however, solid phase sintering stainless steel will remain inside a large number of pores, so that its density and performance reduction. The super-solid phase line liquid phase sintering, so that the stainless steel pre-alloyed powder in the sintering of the liquid phase, the liquid phase through the flow to fill the pores and thus improve the density and performance of the sintered body.
2, different from ordinary liquid phase sintering, super solid phase line liquid phase sintering is the sintering of pre-alloyed powder, and in the sintering process is always a single phase, the sintering temperature is located in the solid phase line and liquid phase line between the temperature of the pre-alloyed particles of grains, grain boundaries and particles on the surface of the formation of the liquid phase, particles in the liquid phase under the action of the capillary force to realize the rearrangement of the curvature of its surface changes in the larger places will be preferred to dissolve, through liquid phase Through the liquid phase flow mass transfer, in the large particles in the depression or pore precipitation, to achieve the purpose of rapid transfer of substances, so that the sintered body to achieve dense.
3, in 1400 ℃ super solid-phase line liquid phase sintering of 316L stainless steel, its density, hardness, wear resistance and corrosion resistance are higher than 1200 ℃ under the solid-phase sintered products. However, because the sintering temperature is too high, the grain will grow too much, resulting in overcooking, should be avoided.
Second, the use of appropriate additives:
1, add some low melting point alloying elements in the powder, through its liquid phase formed during sintering can greatly reduce its porosity, so that stainless steel to meet the higher performance requirements. For example, in 304 stainless steel powder add 2% to 8% of copper-based alloys, due to the low melting point of copper, in 960 ℃ when the liquid phase began to form, to 1000 ℃ when all the formation of the liquid phase, when the temperature is higher than the melting point of copper, the flow of the liquid phase makes the surface pores continue to ballooning and narrowing; due to copper on the stainless steel matrix has a good wettability, can be uniformly distributed in the stainless steel substrate, so that the sintered body of the pore Significantly reduced, microhardness is also significantly improved. In the addition of 8%, 1350 ℃ sintered density increased to 7.05g/cm3.
2, through the addition of suitable reinforcing phase can also improve the performance of powder metallurgy stainless steel, especially mechanical properties. For example, in 316L stainless steel add 1.5% ~ 3% (volume fraction) SiC, due to the interaction between SiC and stainless steel matrix, the formation of a low melting point of Fe-SiC phase, improve the densification of the sintered body, so that its hardness and wear resistance are improved.
The above is about how to improve the density of stainless steel powder metallurgy explained, compared with the traditional melting process production of stainless steel, stainless steel powder metallurgy has the advantages of the parts produced close to the net molding, high dimensional accuracy, high material utilization, uniform organizational structure, etc., and has been widely used in machinery, chemical industry, shipbuilding, automotive, instrumentation and other industries.
How much is stainless steel powder metallurgy processing?
In recent years, with the continuous development of the powder metallurgy industry, stainless steel powder metallurgy is also more and more popular in the market, especially in the automobile, motorcycle accounted for the proportion of the increasing, which is widely used is powder metallurgy gear. Powder metallurgy gears in automobiles, motorcycles accounted for the proportion of stainless steel powder metallurgy parts in other areas are far greater. Compared with the traditional smelting process production of stainless steel, stainless steel powder metallurgy has the advantages of parts shape close to the net shape, high dimensional accuracy, high data utilization, uniform arrangement structure. So how much is stainless steel powder metallurgy?
The following is an introduction to the composition of stainless steel powder metallurgy price:
First: raw materials
Commonly used stainless steel powder metallurgy grade 304, 316, 420, which, according to the price from the beginning of the cheap arrangement, it should be 420-304-316, of course, each grade and imported powder as well as domestic powder points, the price of domestic powder varies, commonly used raw materials for stainless steel powder metallurgy from large enterprises, in line with the U.S. MPIF standards as well as the national standard, so the relative cost is higher! Of course, this is also to ensure stable quality.
Second: structure
Many stainless steel powder metallurgy products can’t be molded at one time, and may also need to involve post-processing, such as drilling and tapping, finishing, turning, etc. These are evaluated according to the processes that require post-processing. Of course, Zhengrang Precision will discuss with customers whether certain processing can be eliminated to achieve the purpose of cost reduction when evaluating quotations.
III: Purchasing Volume
Powder metallurgy process is suitable for mass production with high fixed cost, therefore, the larger the procurement volume of a single batch, the lower the cost.
About stainless steel powder metallurgy price is here, we are choosing stainless steel powder metallurgy products, should not focus on the price, if the quality can not be guaranteed, there is a problem, the loss of the mold fee is still a small matter of delay in production to bear the loss should be greater.
