High pressure advocate program of repair of steam control valve

1. Dish of 1 a powerful person directs 2 aircrew are mechanism of protruding shoulder job the factory makes Oriental turbine (N300 - 16. 537 ／ of 7 ／ 537 - 3 model) turbine, its high pressure advocate steam control valve is by 1 advocate steam valve and composition of 2 control valve, high-pressured control valve is to be used at adjusting the quantity taking steam of high-pressured crock. When aircrew moves, servomotor serves as mechanical takeup, make dish of a powerful person directs protruding shoulder edge directs groove moves up and down, control control valve dish leave degree. When aircrew moves, the high temperature vapour of control valve is 16. 7MPa, 537 ℃ , oriented protruding shoulder basically bears thermal stress and certain Zhou Xiang cut stress action. The dish of a powerful person of control valve of a high pressure and valve base cooperate a diameter to be 170mm, the structure of dish of its a powerful person is shown 1 times like the graph, dimension of oriented protruding shoulder is 10mm of × of 55mm × 30mm (tall × wide × is thick) . Material of dish of a powerful person uses 20Cr3MoWVA alloy steel, be able to bear or endure to raise dish of a powerful person the function of cavitation, its surface has undertaken high temperature nitriding is handled.

1. 2 v material and solder the choice according to control valve job of equipment condition, dish of a powerful person directs protruding shoulder wants to assure to have strength of enough high temperature already, want to satisfy certain wearability again. In view of aircrew rush to repair, cannot purchase optimal match material, consult the chooses principle and mechanical to each v material property analysis of v material, the TIG that chooses as qualitative as ability of mother capable person close - R34 (12Cr2MoWVTIB, Φ 2. 5mm) welding wire. Solder equipment uses LincolnV300 - the 1 arc that reach argon solders tool of form a complete set; Temperature monitoring uses American MX2 infrared ray to measure Wen Yi.

2 weldability can be analysed

Calculate according to carbolic equivalent formula, the main characteristic of material 20Cr3MoWVA is to contain carbon and alloying element more, the welding line when soldering and heat treatment area appear easily strong organization of temper by dipping in water, reach contact when weldment tigidity when stress is greater, produce cold crack easily. Through the dish of a powerful person that nitriding handles, its surface hardness is as high as HV900, when soldering crackle of extremely easy generation.

3 v craft

3. The burnish before solder of 1 craft course is cleaned - warm-up - v - the heat treatment after solder - the turning after solder.

The preparation before 3.2 solder uses horn to clear thoroughly to emery wheel burnish above all the nitriding layer inside limits of 20mm of purify v place, burnish deepness should is more than 0. 4mm, measure the hardness value of burnish place, make sure the area that apply solder achieves HB185 ～ the requirement of 321. Press JB4730 - 94 check mark is accurate, the quality of surface of oriented protruding shoulder after checking burnish must not have the drawback such as crackle, slag inclusion, achieve Ⅰ grade level to be qualification. Clean dish of a powerful person to solder with acetone next place and all round its inside 50mm limits, assure anhydrous, oil to wait; Keep clear of with sand paper of surface of argon arc welding wire smeary wait for dirty content with rusty spot.
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