1.Welding in the T6 condition is often preferred to welding in the T4 condition for 6XXX.
A:错误
B:正确
答案:错误
2.There is no difference of sensitization between ASS and FSS.
A:正确
B:错误
答案:错误
3.High carbon steels are susceptible to solidification cracking because their carbon content is high.
A:错误
B:正确
答案:正确
4.Hardenability, internal stresses and hydrogen are the reasons of underbead cracking.
A:正确
B:错误
答案:正确
5.Peak temperature in HAZ determines the microstructure of the joint of carbon steels.
A:错误
B:正确
答案:正确
6.The resulting structure of whiteheart castings, carbon in a ferrite matrix, is homogenous with better mechanical properties than those of blackheart irons.
A:正确
B:错误
答案:错误
7.Welding such an alloy in its AA condition is most ideal since the strength in the HAZ can be recovered almost completely by postweld natural aging.
A:正确
B:错误
答案:错误
8.In welding QTLA steels,the maximum allowable heat input per unit length of weld can be higher in T-joints than in butt joints.
A:对
B:错
答案:对
9.It is advisable to take advantage of auto-tempering to avoid hydrogen induced cracking in HTLA steels welding.
A:错误
B:正确
答案:错误
10.Specialty tests to evaluate susceptibility to various metallurgically related defects,such as solidification cracking or hydrogen cracking, should be conducted in the alloy development or selection stage.
A:正确
B:错误
答案:正确
11.For HTLA steels, Cr increases the toughness of steels.
A:错误
B:正确
A:错误 B:正确 13.For the alloy in T4 condition, strength loss occurs in joint due to reversion of GP zones.
A:错误 B:正确 14.Low carbon steels are not susceptible to hydrogen induced cracking due to their low carbon content.
A:正确 B:错误 15.Post weld heat treatment of AA or NA is helpful to recover part of strength of alumniu alloys in T6 conditions.
A:错误 B:正确 16.For alloy-lean materials and heat-treatable alloys, non-matching fillers are used to prevent solidification cracking.
A:正确 B:错误 17.The weldability of casting irons mainly depends on the microstructure and mechanical properties .
A:正确 B:错误 18.Whiteheart castings are inhomogenous with a decarburised surface skin and a higher carbon core.
A:错误 B:正确 19.Sometimes, underbead cracks could serve as starting points of fatigue cracking.
A:错误 B:正确 20.Precipitation of GP2 is not expected due to high cooling speed during welding of 6XXX in NA conditions.
A:错误 B:正确 21.The weldability of cast iron is poor comparing to that of low carbon steels.
A:错误 B:正确 22.Comparing with low carbon steels, high carbon steels are with better weldability.
A:正确 B:错误 23.If cooling rate is too high, auto-tempering can't occur during cooling.
A:错误 B:正确 24.In case 3, the depth of the stop hole is equal to ( ).
A:the diameter of the hole B:the length of the crack C:the depth of the crack. D:thickness of the component 25.After welding, QTLA steels can be tempered automatically because they possess ( ) martensite transformation starting temperature and the cooling rate is ( ).
A:low/rapid B:high/rapid C:low/slow D:high/slow 26.Generally, the silicon content of cast irons is generally in the range of ( ).
A:0.6-1.0% B:1.0-3.0% C:larger 3% D:2.0-3.0% 27.HTLA steels are ( ).
A:high carbon B:high alloy C:medium carbon D:low carbon 28.No preheating is recommended during wielding of duplex due to ( ).
A:coarse grain B:deformation C:the formation of ferrite phase D:the formation of sigma phase 29.( ) has been added to the shielding gas to reduce hydrogen in aluminium welds.
A:CCl2F2 B:CO2 C:Ar D:O2 30.Their structure of ( ) consists of branched and interconnected graphite flakes in a matrix of pearlite, ferrite or a mixture of the two.
A:malleable irons B:White cast irons C:SG graphite cast iron D:Grey cast irons 31.HTLA steels are susceptible to reheat cracking because they contain a lot of ( ).
A:H B:carbides C:S D:P 32.( ) are produced from high carbon white cast irons annealed in a decarburising medium.
A:Grey cast irons B:White cast irons C:malleable irons D:SG graphite cast iron 33.What does the reserves of aluminum rank of overall elements in the earth crust?
A:6 B:4 C:5 D:3 34.Hot ductility tests simply measure the ( ) strength and ductility.
A:room B:all temperature C:elevated 35.To avoid liquation cracking, during the welding of HTLA steels, we'd better to pay attention to the content ratio of ( ) to ( ).
A:Ni/Mn B:Mn/Si C:Si/C D:Ni/Si 36.Welding 7xxx alloys in its NA condition is most ideal since the strength in the HAZ can be recovered almost completely by post weld（）.
A:quenching B:natural aging C:anealing D:artifical aging 37.Al–Zn–Mg alloys are more attractive than other aluminium alloys because ( ).
A:they are not susceptible to liquation cracking. B:they recover strength slowly but rather significantly by natural aging C:Post weld heat treatment is not necessary. D:they have smaller tendency to overage 38.Main alloy elements in HTLA steels include ( ).
A:Mo B:Mn C:Cr D:V 39.Effects of Mo in HTLA steels include ( ).
A:improving hardenability B:improving tempering stability C:decreas grain size D:decreas temper embrittlement 40.When to choose Metal Stitching instead of a welding or brazing process?
A:Downtime is critical B:Low cost C:When metal stitching will produce the best repair D:Preheating the whole part is not practical 41.Welding concerns of QTLA steels include ( )
A:toughness decrease B:liquation cracking C:hydrogen induced cracking D:reheat cracking 42.Function of carbon in casting irons includes ( ).
A:Free carbon absorbs vibration and contributes to other beneficial characteristics B:Attached carbon is responsible for hardening C:Over-saturated, free carbon, flake form D:Free carbon prevents it from stretching and bending 43.( ) are heat treatable alloys.
A:7XXX B:3XXX C:1XXX D:4XXX E:2XXX 44.（ ） is heat treatalbe.
A:6061 B:5052 C:7075 D:1100 E:3003 45.（ ） is not heat treatalbe.
A:1100 B:7075 C:6061 D:3003 E:5052 46.Welding concerns of HTLA steels include ( ).
A:toughness decrease B:hydrogen induced cracking C:solidification cracking D:reheat cracking 47.Normally, we'd better pay more attention to hydrogen induced cracking when ( ) are welded by SMAW.
A:plain low carbon steels B:HTLA steels C:plain high carbon steels D:QTLA steels 48.Main alloying elements in QTLA steels include ( ).
A:Cr B:Mn C:V D:Mo 49.The funciton of () is similar to that of Chromium that tends to stabilize alfa-Fe (bcc) and its high-temperature counterpart delta-Fe (bcc).
A:Nb B:Mo C:Mn D:Carbon 50.To avoid hydrogen induced cracking, we have to limit the intrusion of ( ) during welding.
A:H B:P C:C D:S 51.High content of vanadium possibly increase susceptibility of HTLA steels to ( ).
A:solidification cracking B:hydrogen induced cracking C:softening D:reheat cracking
