The mechanical properties of stainless steel most commonly used hardness test trials, static tensile test and impact test. According to the different types of stainless steel, heat treatment, often used in a Brinell hardness test, Rockwell hardness test, Vickers hardness testing.
Brinell hardness testis the diameter of carbide ball a certain value (in the past they used ball) the imposition of test beat into the surface of the sample, the required hold time, the drop test force, and then measure the sample surface indentation diameter. According to the trial force, pressure the ball diameter, indentation diameter to determine the Brinell hardness value.
HB = 0.012
Where: F for the test force (N); D to pressure the ball diameter (mm); d is the indentation diameter (mm), [d = d1 + d2] / 2]; HB is the hardness value. Carbide ball is denoted by HBW, when the ball is denoted by HBS.
In the actual test, according to the test material type, sample size, hardness and other factors, the pressure of the ball using different diameter (diameter of the ball used 10mm, 5mm, 2.5mm, 1mm), and according to the degree of hardness components, can be used F/D2 different ratios, can have 30,10,5,2.5,1. Therefore, the minimum test force is 9.807N, up to 29420N. Load hold time is generally 10 ~ 15s, 20s or longer there.
In the actual test, according to a direct look-up table to determine the indentation diameter of Brinell hardness. Balls of different diameters in the corresponding pressure load, according to the Brinell hardness indentation diameter to determine the value.
Brinell hardness test the submission of the report, unless otherwise indicated hardness value, the material should be marked with the ball, the ball diameter, test power and test power under the hold time.
[Example 1] 285HBW10/3000, said that the carbide ball with a diameter of 10mm, to impose 29420N (3000kgf) test force, under the conditions of 10 ~ 15s to maintain the measured value of 285 Brinell hardness.
[Example 2] 269HBS5/125/20, said steel ball with a diameter of 5mm to impose 1226N (125kgf) test force, under 20s to maintain the measured value of 269 Brinell hardness.
The Brinell hardness test, the sample surface should be smooth, flat, clean surface, surface roughness, generally not more than Ra1.6μm. Specimen thickness should be greater than the indentation depth of more than 8 times. Test center distance of indentation from the edge of the sample should be greater than 2.5 times the indentation diameter, the two center distance between adjacent indentations is at least 3 times the diameter of the indentation.
Measured indentation should be in the same vertical indentation were measured, taking the average of the two measured values for the indentation diameter.
National standards GB/T231.1 "Brinell hardness test Part 1: Test methods", the provisions of the test equipment, sample requirements, test methods and some precautions.
In the heat production site, for large parts can not be Brinell hardness test, which can be portable or Hammer hardness. Brinell hardness of such simple measurement errors.
Brinell hardness test for melting stainless steel, duplex stainless steel solid dissolved, martensitic stainless steel annealing and quenching and precipitation hardening stainless steel, solid solution, aging treatment, the hardness test.
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