Company name: wuxi tianfeng metal products co. LTD
Address: no. 39, zhenze road, huazhuang street, economic development zone, wuxi city, jiangsu province (old factory area)
Address: no.210-2, chengnan road, wangzhuang industrial supporting area (new), new district, wuxi city, jiangsu province
Contact person: +86-1377 1199 895
What are the requirements for quality inspection of induction hardening forgings and ring forgings?
(1) appearance inspection of quenching surface
Check the forging surface for cracks, rust, electric damage and partial melting, and check whether the quenching area distribution is appropriate and whether there are scars and other defects affecting the use. Crack mainly refers to quenching crack and material crack. Because the cracks are relatively small, magnetic particle inspection is usually used for inspection.
(2) surface erosion test
After sand paper is used to remove the oxide film or oxide coating on the surface of hardened forgings, 10%? 25% nitric acid alcohol solvent as etchant, directly on the forging surface, wait for 10? After 20s, the forging surface can clearly show whether there are cracks, soft spots and hardened area forms.
(3) macro inspection of hardening layer
1) fracture inspection diameter less than 25? For shaft forgings with induction hardening of 300mm, grind a gap on the grinder, and then break it with hammer or press to observe the fracture directly. The hardened layer in the fracture presents fine gray-white stubble (surface layer) while the hardened part in the middle presents rough stubble.
2) section corrosion in the induction hardening area of forgings, one or more sections are selected for section, section samples are taken out, and samples are prepared. After corrosion treatment, macroscopic observation can be carried out to obtain the distribution of hardening layer and relatively accurate depth of hardening layer.
Corrosive: copper gasification ammonium gasification reagent; A solution of alcohol nitrate. A solution of nitric acid alcohol with a concentration of about 10%. The corroded specimens showed that the hardened layer was bright white, bright gray or bright black, while the original tissue part was light gray.
(4) surface hardness test
1) hardness tester test of surface hardness
When the hardened layer of the induction hardening forgings is > 0.8mm, the C scale (HRC) of the rockwell hardness tester is often used for inspection. For forgings with hardened layer < 0.8mm, surface rockwell hardness tester and vickers hardness tester can be used. The surface of rough parts must be polished with a file and sandpaper. If the forgings under test are normalizing or tempering in the pre-heat treatment, the scale and decarbonization layers must be polished, but the depth of grinding shall not exceed the machining allowance. The number of inspection points for each item should not be less than 3. The surface hardness fluctuation range of the induction hardening parts can refer to the relevant provisions of ZBJ 36005. The surface hardness test shall be performed in accordance with the relevant provisions of JB/T 9201 "induction quenching and tempering treatment of steel parts".
2) file examination of surface hardness
Refer to GB/T 13321 steel hardness file test method.
(5) depth measurement of hardened layer and metallographic examination of hardened layer
1) hardness test of hardened layer depth of forgings
Method GB/T 5617 "determination of effective hardening depth of steel after induction quenching or flame quenching" was performed, and the effective hardening depth was expressed by.
2) metallographic examination of hardened layer of forging
The induction quenching metallographic inspection standard for steel parts ZBJ 36009 shall be implemented. The ideal microstructure for induction quenching is 4/6 grade microstructure. If the lower limit of the surface hardness specified in the product drawing is higher than or equal to 55HRC, the 3/7 grade is qualified; When the lower limit is less than 55HRC, level 9 is considered barely qualified. After grinding, the metallographic specimens are etched with a solution of 2%-5% nitric acid alcohol containing a volume fraction. In addition to the observation and inspection of the metallographic structure of the hardened layer, the original structure of the unhardened zone should also be inspected to see whether there are problems such as coarse grain, bulk ferrite or banded structure, etc., especially when the hardness of the hardening forging is not enough, the depth of the hardened layer is not enough or not even.