Concept of hardness conversion table

Hardness states material resists hard object controls the capacity of its surface. It is one of main function index of metallic stuff. General hardness is taller, wearability is better. Commonly used hardness index has hardness of cloth family name, Rockwell hardness and diamond pyramid hardness.

Hardness of 1. cloth family name (HB) with certain load (general 3000kg) certain size (the diameter is 10mm commonly) ball of hard steel of temper by dipping in water presses material face, hold period of time, after carry, the ratio of bear and its impress area, be worth for hardness of cloth family name namely (HB) , the unit is kilogram of force / Mm2 (N/mm2) .

2. Rockwell hardness (HR) be more than when HB 450 or sample spends a hour, cannot use cloth family name to hardness experiments and convert Rockwell hardness plan. It is to use the diamond cone of 120° of a vertex angle or diameter to be 1.59, the steel ball of 3.18mm, in face of the material that be measured is pressed below certain load, beg the hardness that gives data by the deepness of impress. According to test data hardness different, divide HRA of kind of different hardness staff guage: It is to use 60kg load and diamond awl to be pressed implement gotten hardness, use at hardness extremely expensive stuff (wait like hard alloy) . HRB: It is to use 100kg load and diametical 1.58mm the steel ball with hard temper by dipping in water, gotten hardness, use at the material with inferior hardness (like anneal steel, cast-iron etc) . HRC: It is to use 150kg load and diamond awl to be pressed implement gotten hardness, use at hardness very expensive stuff (if quench steel) .

3 diamond pyramid hardness (HV) awl controls the diamond square that is 136° with the load of 120kg less than and vertex angle implement press material face, with the watch of material impress indentation the area is divided be worth with load, be worth for diamond pyramid hardness namely (HV) . According to German standard DIN50150, of hardness of family name of the rolled steel tensile strength that is commonly used limits below and diamond pyramid hardness, cloth, Rockwell hardness contrast watch. Hardness experiment is the method of goes easily the simpliest a kind of experiment in mechanical function experiment. To can replace certain machine with hardness experiment function experiments, the conversion that a more accurate hardness and strength need on production concerns. Carry out a proof, between all sorts of hardness values of metallic stuff, hardness value and intensity have similar corresponding concern between the value. Because hardness value is,be out of shape by initiative plasticity fight force and continue plasticity is out of shape of the decision that fight force, the intensity of material is higher, plasticity is out of shape fight force taller, hardness cost is higher also.
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