Production and Application
Stainless chromium steel 90H18MF smelted in an open electric arc or induction furnaces. Production is regulated by GOST 5632−72 and 5949−75, and TU: 14−1-1848−75 and 14−1-4628−89. Band-pass and high-grade steels are manufactured by forging or rolling. Hot deformation is carried out at 1130−950 ° C, followed by holding at 750 ° C and cooling. In the hardened state of such steel is used in the production of fibers, multi-threaded gear pumps for dosed feeding preparative media, and also in the manufacture of (GOST 328.1−92 50) of the cutting tool in the medical and food industries, corrosion resistant sanitized.
The percentage of
Physical properties at 20 ° C
Density 7.67 g / cm3 and resistivity of 0.68 micro ohms • mm2 / m.
Temperature coefficient of linear expansion and
|steel grade||From 20 to 100||From 20 to 200||From 20 to 300||From 20 to 400||From 20 to 500||From 20 to 800|
Steel 90H18MF extremely corrosion-resistant. During the test, among the production of polyester filament yarn (pH 4.3−4.8), it does not change, while the martensitic steels such as the 40X11MZF, 50H14MF and 95X18 undergo pitting corrosion.
Steel 90H18MF refers to the martensitic class. Its microstructure by quenching from 900−1250 ° C forms martensite, austenite, carbides. After annealing the structure ledeburite steel with excessive carbides which differ morphologically. Primary separated from the liquid phase, are extended along bigger rolling or forging. Secondary — small, stand over the boundaries during cooling, as well as within the austenite grains. With increasing heating temperature for quenching the proportion of retained austenite increases and the change hardness. The minimum value of 26 HRC hardness obtained by quenching from 1250 ° C, while the maximum value of 57−58 HRC by quenching from 1050 ° C.
Effect of quenching on the properties tº 90H18MF (numerator) and 95X18 (the denominator)
|tzak||The residual austenite γ,%||Austenitic grain diameter in microns||Hardness HRC||The content of chromium (Cr) in solid solution,%|
|900 ° C||<1||18||47||9.5|
|1000 ° C||-||16||55/55||-|
|1050 ° C||26/17||40||57/58||eleven|
|1100 ° C||-||-||54/55||12.2|
|1150 ° C||76||35||40||-|
|1200 ° C||-||42||33||-|
|1250 ° C||93||63||26||16.4|
Influence tº holiday on properties 90H18MF (numerator) and 95X18 (denominator) (the process of quenching from 1040 ° C)
|totp, ° C||Hardness HRC||The residual austenite γ,%||totp, ° C||Hardness HRC||The residual austenite γ,%|
|140||57/56||17/15||670||33 / -||0 / -|
|300||52/51||12/12||750||27 / -||15/-|
|500||55 / -||-||900||60 / -||0 / -|
|600||40 / -||-||-||-||-|
After quenching the steel 90H18MF in oil with 1040 ° C (30 minutes delay), the critical points are: Ac1 = 840 ° C, Ac3 = 925 ° C; Mn = 260 ° C; MC = 135 ° C. Due to the stability of the austenite after hardening from 1250 ° C no phase transformations. tempering temperature from 900 to 1250 ° C dependent on the chromium content. After quenching from 900 ° C primary carbides have grain 1,6−7,6 mm, secondary — 0.4−0.8 microns. With increasing temperature, quenching to 1150 ° C the size of primary carbides is almost unchanged. Recommended quenching tº 1050 ° C, and tempering 140 ° C. To mitigate complete (~ 220 HB) is carried out annealing at 880−920 ° C with minimal cooling rate (25 ° C / h). To improve the machinability in turning using annealing at 730−760 ° C. Not recommended tempering at 450 to 600 ° C and t ° quenching above 1065 ° C, which causes grain growth and decrease toughness.
In stock «Electrovek-steel» company offers a wide range of brand rolled 90H18MF any parameters. The technical documentation includes data on the chemical composition, limiting the percentage of impurities; mechanical properties of products. We can buy in bulk, any semi-finished products for large-scale productions. We also offer optimal conditions for retail customers. High level of service and efficiency of service are the face of our company.
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