《The hardness and thickness test method after nitriding (nitrogen).doc》由会员分享，可在线阅读，更多相关《The hardness and thickness test method after nitriding (nitrogen).doc（14页珍藏版）》请在三一文库上搜索。
1、The hardness and thickness test method after nitriding (nitrogen)The hardness and thickness test method after nitriding (nitrogen)Release time: 11-08-03Source:Click: 1528Field choice: large medium smallThe hardness and thickness test method of nitriding of steel parts:With the development of industr
2、y, the treatment of nitride is more applied in all walks of life, and the detection requirements for nitrous treatment are also increasing. The hardness and thickness of the steel parts for nitride treatment are briefly explained by the Beijing times peak technology co., LTD.Nitriding (gas nitriding
3、, ion nitriding, carbonitriding, glow ion nitriding) parts is the main technical requirements of the effective depth of nitriding layer, surface hardness and hardness. In order to complete the above requirements, it is required to measure the hardness of the nitride layer.The nitride layer is divide
4、d from the gold phase, including from the outer layer of the layer (the white light layer) to the deep layer of the diffusion layer and the visible division of the matrix. Microdimensional hardness testing, based on the surface of the workpiece, the vertical distance of the hardness value is clearly
5、 defined.The nitride depth is indicated by the letter DN.Depth hardness testing method:Sample preparationA and test samples should be cut from the nitride parts, such as the workpiece can not be damaged, and can be tested after the small samples of the same materials and the same processing techniqu
6、es.B, taking note, when sample should be vertical nitriding layer surface of the sample (see the metallographic specimen sampling method), sampling necessary after the polishing processing, cooling should be paid attention to in the polishing process, cannot make workpiece overheating, dont appear c
7、hamfering edge, etc.C, check for the brittleness of the nitride layer, the surface roughness requires Ra0.25-0.63 um, but not allow the surface compound to be ground down.2, testA, according to gb regulation, generally choose micro hardness tester, testing force usually choose 0.3-1 kg, from the sam
8、ple surface measurement to higher than matrix vickers hardness value 50 hv vertical distance as the nitriding layer thickness. (usually a ladder hardness test, which starts at the surface of the sample, and at a certain distance per interval.)B, matrix hardness take and determination, usually in abo
9、ut three times the depth of nitriding layer distance measured hardness value (at least 3 points, average) as the matrix hardness value.C, for nitriding layer hardness change very flat steel, such as carbon steel, low carbon alloy steel parts, the depth of nitriding layer can be measured from the sam
10、ple surface along the vertical direction to 30 hv is higher than matrix vickers hardness.D, when the nitride depth is particularly shallow, and some are deeper, the detection force can be selected within 0.2 KG (and noted, such as HV0.2).E, the results indicate that the depth of the nitride is in th
11、e letter DN, the depth is in millimeters, and the decimal point is two. (for example: 0.35 dn300hv0.3, the thickness of the nitride layer is 0.35 mm, the threshold hardness value is 300HV, and the test force is 0.3 KG.Minimum effective nitride depth (DN) and upper deviation table recommended by gene
12、ral partsUnit/mmEffective nitriding depth DNThe deviationEffective nitriding depth DNThe deviation0.050.020.350.150.10.050.40.20.150.050.50.250.20.10.60.30.250.10.650.30.30.10.750.3The total depth of nitrideRefers to the total nitrogen infiltration depth, generally refers to the measured from the su
13、rface to the substrate hardness or organization have obvious differences in vertical distance, the unit is mm, include all of the compound layer and diffusion layer. Special instructions should be given when the parts are substituted for the DN requirements in the compound layer thickness. The thick
14、ness requirement varies with the service condition of the part4, the thickness of the compoundThe compound layer is mainly composed of Fe3N and a small number of Fe4N and Fe3C, and the compound is of high hardness, which improves the wear resistance and corrosion resistance of the parts.The thicknes
15、s of the compound and the tolerance table (unit/mm) recommended by general parts.Compound thicknessThe deviationCompound thicknessThe deviation0.0050.0030.0120.0060.0080.0040.0150.0080.0100.0050.0240.012The brittleness test of nitride layerThe level of brittleness of the nitride layer was divided in
16、to five levels according to vickers hardness indentationlevelThe nitride layer brittleness level specificationoneThe indentation edge is intact2The indentation, or the tip of the scratch3Crushed by two or two corners4The triangulation of the indentation or triangulation of the triangle5The margin of
17、 the indentation is broken by four sides or four cornersB, nitriding layer brittleness test generally USES the vickers hardness tester, testing force 10 kilograms, the test force load must be slow (finish) in 5-9 s, after the completion of the loading test force must stay 5-10 s, and then unloading
18、test, special circumstances can also be 5 kg or 30 kg test force.C and vickers hardness indentation are examined by 100 times micromagnification, at least 3 points per piece, at the same level at least two points. Otherwise, it will be re-examined.D, nitriding layer brittleness parts should work in
19、part or on the surface of the sample testing with furnace, general parts for qualified for grade 1 to grade 3, important parts for qualified grade 1-2, for parts after nitriding with grinding crack, can also be used in grinding to the determination on the surface after machining allowanceE, after ga
20、s nitride parts, must be tested.The depth of depth (thickness) of the steel case carburizing/carbon nitrification.Hardened depth (cement-hardened layer) : the vertical distance from the part surface to the vickers hardness value of 550HV1.Scope of application:This method is suitable for cementation
21、of carburizing and carbonitriding. After heat treatment, the hardness value is less than 450HV. For three times the distance from the surface of the quench hardening layer depth of steel hardness value is higher than 450 hv, the determination method is also applicable, premise condition is to choose
22、 the hardness value is greater than 550 hv (level 1) on a 25 hv a particular value as the limit of hardness.Said method:The hardened depth is expressed in CHD, the unit is mm. Such as the CHD = 0.5 mm.The strength of the test was 9.807 N (1kgf). The special case can be chosen from 4.903 N - 9.807 N,
23、 which is the value of the hardness limit that can be applied to other values other than 550HV1.Depth measurement:Sample preparation: the sample is usually sampled vertically after the final heat treatment, and the necessary grinding and polishing (please refer to the production of gold samples). Te
24、st the cross section of the sample. Special circumstances may be adopted with the furnace test specimen.Measurement method: in width (W) for 1.5 mm range (i.e. width of test area),It is used to measure vickers hardness on one or more parallel lines perpendicular to the part surface. The distance (S)
25、 of each of the two adjacent indentation centers should not be less than 2.5 times of the diagonal of the indentation, and the test will be suppressed in a straight line. The distance difference between the center of the successive indentation center to the surface of the parts (a2 - a1) should not
26、exceed 0.1 mm. The distance accuracy of the measuring center to the part surface should be within the range of plus or minus 0.25 um, and the measuring accuracy of the diagonal shall be less than 0.5 um. The test force is usually HV0.1 - HV1 gets the vickers hardness indentation, and USES a magnific
27、ation of over 400X.3, depth to determine: according to the test of two (or more) indentation line, determine each of the 550 hv indentation hardness value to get the line to the distance on the surface of the parts, if two lines of numerical differential is equal to or less than 0.1 mm, then take th
28、eir average value as the depth of hardening layer. If the difference is greater than 0.1 mm, the test should be retested.Hardened depth check:In the case of depth, it can be applied to the inner interpolation method (the gradient approximation of the hardness gradient in the transition zone near the
29、 hardened depth base hardness). In parts of vertical section, from the position of the part surface d1 and d2 in the 5 (suggest point into a line parallel to the workpiece surface), and d1 and d2 respectively is less than and greater than determine the depth of hardening layer (i.e. to determine dep
30、th of hardening layer for the baseline, d1 close to the direction of the surface hardened layer, d2 near parts matrix direction) (d2 - d1) values should not be more than 0.3 mm.Depth CHD = d1 + (d2 - d1) X (H1 - H3)/(H1 - H2)D1: less than hardened depth (unit mm)D2: greater than hardened depth (unit
31、 mm)H3: specified hardness valueH1: the average hardness value of d1H2: average hardness value at d2Note: when using interpolation method, it is better to check under the close to the surface area of hardness, if too much retained austenite on the surface of The Times, the hardness of the area to be
32、 less than the limit of 550 hv hardness value.The hardness and quenching thickness (depth) test method for the hardened and hardened steel parts:Effective hardening depth (DS) : the distance between the surface of the part and the hardness of the limit.Extreme hardness (HVHL) : refers to the minimum
33、 required parts surface hardness (HVMS) multiplied by the coefficient of HV1 test force coefficient can usually choose 0.8, also can choose 0.9 or greater (such as the surface hardness is 320 hv, so extreme hardness = 320 x0. 8 = 256 hv).Selection of experimental forcesIt is usually chosen to use th
34、e microvickers hardness tester, which is usually chosen as HV1 (9.807 N) and can be used in a 4.9 to 49N range.2, testThe tests shall be conducted within one or more areas of the prescribed sample surface, and indicated on the drawing.B, test specimen preparation:The test specimen should be cut in t
35、he vertical hardening surface, and the surface is cut off as a test surface. The inspection surface should be ground and cast, so that it can be polished as mirror. In the process of cutting and grinding, avoid overheating, deformation and Angle of reverse. See the preparation process of gold phase
36、sample preparation in the technical articles section.C, hardness detection:Hardness indentation should play in the perpendicular to the surface of one or more parallel lines, and the width of 1.5 mm area, on the surface of the indentation on the surface of the closest to the center and the distance
37、of 0.15 mm, the distance from the surface to the center of each successive indentation should be increased by 0.1 mm at a time. When the surface hardening layer depth is big, the indentation of center distance can be larger, but near the extreme hardness area nearby, should still maintain the distan
38、ce between the center of indentation is 0.1 mm.D, measurement results:The depth of the effective hardening layer is determined by the hardness of the cross section of the vertical surface. Determined by drawing the hardness change curve, from the part surface to the hardness value is equal to the di
39、stance limit hardness, this distance is effective after induction hardening or flame hardening depth of hardening layer.Remark:In a region with multiple hardness curves, it is necessary to take the depth of the hardened layer of the curve, as an effective hardening depth. The effective hardening depth is indicated by the letter DS, the depth unit is mm, such as the depth of the hardened layer 0.5 mm can be written as DS0.5