Welder theory examination reference question bank and answer

A joint with an Angle between the surfaces of two welds greater than or equal to 135° and less than or equal to 180° is called (A). A. butt joint B. t-joint C. lap joint D. Angle joint (302) Electric shock accidents can be divided into direct shock and (B). A. Indirect shock B. indirect shock C. Interval shock D. accidental shock (303) Each live part of the welder and its shell to the ground must meet the requirements of the insulation standard, and its resistance value is not less than (C). A. 2 M Ω b. 1.5 M Ω c. Ω d. 1 M 3.5 M Ω The length of welding cable is generally (A) m. A.2 ~ 3 B.2 ~ 5 C.1 ~ 3 D.2 ~ 4 (305) The explosion limit range varies with temperature and (B). A. expansion B. pressure C. volume D. concentration (306) The mechanical properties of metal materials subjected to external load from the initial stress until the material is destroyed are referred to as (D). A. strength B. casting properties C. welding properties D. mechanical properties (307) A continuous and intense discharge in the airflow medium between the workpiece and the electrode is called (A). A. electric arc B. electric current C. electronic pulse D. gas cutting (308) In the field of mixed operation, when it is impossible to ensure a safe distance of 10m cylinders in the workshop, it can be used (A) Gas cylinders should be properly placed outside the workshop. A. through the wall B. away C. through the passage D. by car (309) The Work Safety Law provides that other production and business entities are encouraged to employ (D) for work safety management. A. Senior Engineer B. Economist C. Safety Engineer D. Registered Safety Engineer When the pressure is 0.15MPa and the temperature exceeds (B), acetylene can be made to explode by itself. 580 ℃ 480 ℃ a. b. c. 630 ℃ d. 280 ℃ In order to minimize the surface damage of the weldment, arc initiation should be scratched at the welding groove, and the scratched length should be (C). A.20 ~ 30mm b. 50 ~ 60mm c. 20 ~ 25mm d. 40 ~ 50mm (312) Welder’s insulating gloves shall not be shorter than (D) mm. A.50 B.80 C.100 D.300 (313) A metal formed by the combination of two or more elements, at least one of which is a metallic element, is called (C). A. solid solution B. mechanical mixture C. alloy D. compound The lower the explosion limit, the more dangerous (A). A. large B. small C. low D. controllable When the welder is grounded, the total resistance of the grounding line shall not exceed (B) ω. A.2 B.4 C.5 D.10 (316) The width of the footboard shall not be less than (D) m during the ascending operation. A. 1 B. 2.5 C. 1.5 D. 1.2 (317) The ground electrode of the welder shall not be less than (B) m in depth. A. b. 1.2 1 C. 3 D. 0.5 The minimum distance from the toe of one right-angle plane to the surface of the other right-angle plane is called (B). A. welding seam B. welding foot C. thickness of welding seam D. penetration (319) All other work by fire shall be prohibited within (D) m of the ignition point. A.100 B.5 C.20 D.10 (320) The flame temperature of gas welding and cutting can be as high as (D). A.300 ~ 850℃ B.400 ~ 900℃ C.300 ~ 2500℃ D.3200℃ (321) The key safety measures of pressure non-displacement welding are (B). A. Properly adjust welding parameters b. positive pressure operation C. low combustible gas concentration D. high technical level of operator (322) Maintaining (C) pressure at all times is one of the key safety measures to ensure that there is no displacement of ignition with pressure. A. low B. high C. positive D. negative (323) The method of carbon arc gouging is to reduce the dust pollution of carbon arc gouging by spraying the compressed air with a large amount of water mist. Water carbon arc gouging can reduce ambient dust by (B) or so. A.70% B.40% ~ 60% C.20% ~ 40% D.80% The load persistence rate of submerged arc welder is (A). A.100% B.90% C.80% D.50% (325) The essentials of first aid for electrocution are (A). A. Timely treatment and correct method B. correct treatment and simple method C. timely reporting and correct method D. Timely treatment and correct planning The safe voltage for underwater operation is (B). B. a. 3.5 V to 2.5 V C. 2.0 V d. 2.8 V (327) No (B) safety belt shall be used in welding and cutting operations. A. canvas seat belt B. nylon seat belt C. leather seat belt D. Standard seat belt (328) Electric welding holder shall be easy to operate and the weight of the holder shall not exceed (C). A.500g B.1200g C.600g D.850g (329) Steel is tempered at high temperature after quenching, and this composite heat treatment process is called (A). A. tempering B. normalizing C. annealing D. tempering (330) The droplet transition form is (D) transition. [A]. [B]. [C] (331) LPG is denser than air (A). A. large B. small C. same D. smaller in liquid form When acetylene is mixed with air, the explosion limit is (B). A.22 ~ 81% B.2.2 ~ 81% C.2.2 ~ 8.1% D.2.2 ~ 18% (333) All (B) shall be opened when welding pipes and containers. A. Valve B. hole cover C. switch D. Observation hole (334) During the welding and cutting operation of climbing, the Angle of step ladder used is (B). B. a. 50 ° + / – 5 ° 40 ° plus or minus 5 ° c. to 45 ° + 5 ° d. 60 ° plus or minus 5 ° (335) Iron-carbon alloys with carbon content below (A) are called steels. 21% 2.11% a. b. c. d. 21.1% 3.11% (336) Acetylene spontaneous combustion point is (B), easy to be heated spontaneous combustion. 335 ℃ 300 ℃ a. b. c. 200 ℃ d. 130 ℃ (337) When an electric shock occurs, the first is (C). A. Use one hand to pull the electrocutor b. Call A doctor C. Cut off the power D. artificial respiration (338) Gas cutting is A method that uses the heat energy of gas flame to preheat the cutting part of the workpiece to A certain temperature, and then spews out high-speed cutting (A), using combustion to achieve cutting. A. oxygen flow B. acetylene flow C. air flow D. electric arc The resistance value of the human body is generally (C) ω. A.50 B.80 C.1000 D.10000 (340) The commonly used power frequency alternating current is more reasonable for electrical equipment, but from A safety point of view, it is the most dangerous frequency for human body, (A) Hz alternating current has the greatest effect on cardiac muscle. A.25 ~ 300 B.10 ~ 25 C.35 ~ 200 D. more than 300 (341) In the process of heat treatment of steel, after quenching (D), toughness of steel can be restored while maintaining a certain strength. [A]. [B]. [C] (342) Metal suitable for gas cutting whose ignition point is (B) melting point. A. more than B. less than C. equal to D. including (343) The most dangerous route of electric current through the human body is (D). A. right hand to left hand B. left hand to right foot C. left foot to right foot D. left hand to chest According to the marking principle of weld dimension symbols and data, the dimension on the cross section of the weld is marked in (B) of the basic symbol. A. right B. left C. upper D. lower In case of fire in carbide barrel or carbide warehouse, only dry sand, dry powder or carbon dioxide fire extinguishers should be used. (A) A. water B. broom C. wet covering (346) In order to ensure penetration at the starting point of the weld, the electrode can be swung horizontally and slightly stopped on both sides of the root of the groove to form A (A) of A certain size. A. pool B. weld C. groove D. welding height The distance between high-pressure cylinders and radiators and electrical equipment shall be greater than (B) m. A.2 B.3 C.5 D.10 (348) Welding machine fire is found in response to (A). A. put out the fire after pulling the brake and cutting off the power B. put out the fire before pulling the brake and cutting off the power C. splash water D. use foam fire extinguisher (349) Acetylene cylinders or acetylene generators and oxygen cylinders shall be placed away from the working area (C) m during welding and cutting operations. A.12 B.5 C.10 D.20 (350) The flow rate during underwater welding and cutting shall not exceed (C). 1.3 m/s a. b. 1 m/s c. 0.3 m/s d. 0.1 m/s The working medium used by water jet cutting is (B). A. high density B. high pressure C. airflow D. high voltage A weld welded between the groove face of the weldment or between the groove face of one part and the surface of another part is called (C). A. fillet weld B. plug weld C. butt weld D. slot weld Explosive welding is A method of intermetal welding using (A) as energy source. A. explosive B. electric CURRENT C. high temperature D. pressure (354) In order to eliminate dendrite segregation in alloy ingot and casting during crystallization, the annealing method used is (D). A. Complete annealing B. isothermal annealing C. spheroidizing annealing D. diffusion annealing (355) Vibration-proof rubber rings should be installed on oxygen cylinders. Check whether (C) on the cylinders is tightened before handling. A. bolt B. stud C. safety helmet D. nut (356) Although there are many methods of heat treatment, any heat treatment consists of (A) three stages. A. Heating, insulation and cooling B. heating, insulation and transformation C. Normalizing, hardening and annealing D. Tempering, quenching and annealing (357) for gas welding, the oxygen acetylene ratio is greater than (A). A. 1.2 B. 1.1 C. D. 1.6 1.0 (358) Welding current is too small to easily cause weld defect is (C). A. A b. A C. A D. A (359) The transformation of a metal in a solid state from one lattice to another with temperature is called (C). A. lattice transition B. crystal transition C. isomeric transition D. isomeric transition The preheating temperature of cast iron during gas welding is (D). A.200 ~ 350℃ B.200 ~ 450℃ C.200 ~ 550℃ D.200 ~ 650℃ The GS line in the iron carbon phase diagram is the beginning of the precipitation of ferrite from austenite during cooling, and the transformation from austenite to ferrite is (B). A. Results of carbon saturation in austenite B. Results of isomerization of solvent metal C. Results of isomeric transformation of solute metal D. results of eutectoid transformation of austenite (362) Most of the alloy structure belongs to (C). A. metal compounds B. single solid solutions C. mechanical mixtures D. pure metals During the cooling transformation of eutectoid steel, the greater the cooling speed, the smaller the lamellar spacing of pearlite structure, and the strength and hardness (A). A. higher B. lower C. constant D. independent of cooling rate (364) When workpiece hardness is higher than the annealing defect, the remedy is (A). A. Adjust heating and cooling parameters for A new annealing B. Normalize C. Do one tempering. D. None of the above With the increase of tempering temperature, the change trend of mechanical properties of quenched steel is (A). A. Strength, hardness, plasticity and toughness are improved. B. Reduced strength and hardness, reduced plasticity and toughness. C. Strength and hardness increase, plasticity and toughness decrease D. strength and hardness decrease, plasticity and toughness increase. (366) For eutectoid steels, it is necessary to eliminate severe reticular secondary cementite in favor of spheroidizing annealing (C). A. isothermal annealing B. diffusion annealing C. normalizing D. safe annealing The moderate tempering temperature is (C). A.150 ~ 250℃ B.350 ~ 500℃ C.500 ~ 600℃ D.250 ~ 350℃ (368) Bainite structure, the best mechanical properties is (B). A. upper bainite B. lower bainite C. granular bainite D. globular bainite (369) The method of annealing to eliminate residual internal stress in castings, welds and machined parts prior to finishing or quenching is (B). A. diffusion annealing B. stress relieving annealing C. spheroidizing annealing D. complete annealing When austenite grains are uniform and fine, the strength and toughness of steel change as (C). A. strength increased, plastic toughness decreased B. strength decreased, plastic toughness increased C. strength increased, plastic toughness increased D. Reduced strength, reduced plastic toughness (371) Granular pearlite compared to flake pearlite, granular pearlite (C). A. Low strength and high plasticity B. High strength and low plasticity C. High strength and high plasticity D. Low strength, low plasticity (372) The purpose of carburizing is to provide high hardness, wear resistance and fatigue strength on the surface of the parts, while the core has (A). A. higher toughness B. lower toughness C. higher plasticity D. lower plasticity (373) The heat treatment method for obtaining spherical pearlite structure is (B). A. Complete annealing B. spheroidizing annealing C. stress relieving annealing D. recrystallization annealing The potential of A point in the circuit is that point and (A) in the circuit. A. Voltage between zero potential points B. Resistance between zero potential points C. Voltage between reference points D. Resistance between reference points (375) The heat of a current passing through a conductor, in addition to being proportional to the resistance of the conductor and the energized time, is (C). A. proportional to the strength of the current B. inversely proportional to the strength of the current C. proportional to the square of the strength of the current D. Inversely proportional to the square of the current intensity (376) The Work Safety Law provides that: the state encourages production and business operation entities (B) work safety liability insurance. [A]. [B]. [C] During normal welding, the static characteristic curve of arc is u-shaped curve (C). A. steep descending section B. slow descending section C. horizontal section D. ascending section The static characteristics of submerged arc welding under normal current density are (A). A. flat characteristic zone B. rising characteristic zone C. steep characteristic zone D. slow descent characteristic zone The force unfavorable to droplet transition in inverted welding is (A). A. gravity B. surface tension C. electromagnetic force D. air force (380) The arc temperature in the chemical metallurgy process of welding is very high, generally up to (C). A.600 ~ 800℃ B.1000 ~ 2000℃ C.6000铜焊丝,Copper Welding Rods,铝焊丝,aluminium welding wire,镍焊条,Nickel electrode,药皮焊条,Flux Coated Brazing Welding Rods