2. Hardness refers to the ability of metal materials to resist surface deformation (refers to the ability of the surface to resist the invasion of foreign objects).
3. Many important products, due to the use of low alloy, not only greatly save steel, improve hardness and wear resistance, but also greatly improve product quality and service life. (right)
4. Before welding, the welder should carry out safety inspection on the mask, mainly including corrosion resistance, heat insulation, light reflection and anti-virus performance. (x) It should protect eyes from ultraviolet rays.
5. Thorium is an ideal electrode material for TIG welding, and it has no radioactivity (right).
6. Tungsten electrodes include pure tungsten electrodes and thorium tungsten electrodes. Cerium tungsten electrode, zirconium tungsten electrode. At present, the latter three (X) are commonly used.
7. During butt-joint assembly of plates, the assembly gap should be determined according to specifications and welder skills, and the gap between the final welding end and the initial welding end should be the same. (x) The final welding end gap should be larger.
8. There are three kinds of submerged arc welding power sources: DC power source, AC power source and rectangular wave AC power source (right).
9. There is no waterway system in manual TIG welding equipment (right).
10: semi-automatic CO2 gas shielded welding machine consists of power supply, wire feeding structure, conductive system, welding torch and water cooling system. )
1 1: The height of flux accumulation in submerged arc automatic welding is generally 2.5-3.5mm(X).
12: TIG welding of aluminum, magnesium and their alloys should adopt DC reverse connection (reverse connection).
13: seam welding is mainly used for thin-walled containers requiring air tightness, and the wall thickness is generally less than 4mm( X).
14: The distance between spot welds is the specified value (x) that meets the structural strength requirements.
15: the control box of plasma arc cutting equipment mainly includes program control device. High frequency oscillator. Electromagnetic valve and water pressure switch, etc. (right)
16: Hydrogen in the weld metal of steel will not cause hot cracks (right)
17: The welding material is the factor that affects the performance of welded joints. Welding process method. Welding process parameters. Fusion rate. Welding operation method and post-weld heat treatment (right)
18: both shrinkage deformation and thermal deformation are welding deformation (x)
19: the rigid fixing method is very effective in preventing the deformation of the thin plate, especially in preventing the wave deformation caused by the longitudinal contraction of the weld (x)
20: The calculation formula of carbon equivalent recommended by International Welding Society is applicable to carbon steel and diamond (X).
2 1: When welding low-alloy structural steel with yield point above 295MPa, preheating is generally required. (right)
22: The local preheating of pearlite heat-resistant steel before welding must ensure the preheating width, which is more than 4 times the thickness of the welding wall on both sides of the weld, and at least not less than 250mm (right).
23: W707 is pearlite heat-resistant steel covered electrode (opposite).
24: When welding austenitic stainless steel, arc (X) can be struck on the working face.
25: Ar+5- 10%O2 rich mixture is generally used for argon arc welding of austenitic stainless steel. )
26: Using small line energy is one of the measures to prevent blowholes (right).
27. The main reasons for incomplete penetration are: the bevel angle is too small, the blunt edge is not enough, the assembly gap is too small, the welding current is too small, the welding speed is too fast, the welding angle is not suitable, and the arc is blown off (right).
28: The purpose of bending test is to determine the toughness of welded joint (right)
The purpose of impact test is to determine the toughness (X) of welded joint and weld metal.
Excuse me, call? I don't know the size.