2007年《机械工程材料》试题(双语考卷B及答案)

华南理工大学期末考试

《 机械工程材料 》试卷B---闭卷部分

4. 一律用中文答题

5. 本试卷共 5 大题，满分100分，考试时间120分钟。

题 号 一 二 三 四 五 总分

得 分

评卷人

1.In the Al-20%Cu alloy, does the first solid solution which forms on cooling contain ___c__

a)20% Cu

b)less than 20% Cu

c)more than 20% Cu

d)no Cu (i.e. pure Al)

2.In solidification, which of following mechanisms or steps best describing the process?___b___.

a)cooling and reheating

b)nucleation and growth

c)melting and cooling

d)none of the above

3.To ensure the extreme elasticity of spring made by 60Si2Mn steel, what microstructure should be

obtained after quenching and 450°C tempering. __d_

a)tempered bainite

b)tempered martensite

c)tempered sorbite

d)tempered troostite

4.For the equilibrium microstructure, the mechanical properties of steels are mainly influenced by the

amount, morphology and distribution of a

a)cementite

b)ferrite

c)martensite

d)pearlite

5.The grain size of solidified metals will not be affected by _c___

a)the cooling rate

b)the growth model of crystal

c)the artificially added impurity

6.Materials strengthening methods include ___a b c d__

a)solution strengthening

b)fine grain strengthening

c)work hardening

d)case hardening

7.Recrystallization process will not change the _b c__ of materials.

a)grain size

b)chemical composition

c)crystal structure

d)imperfection density

8.The purpose of cold treatment is to eliminate the ___b__.

a)stress

b)residual austenite

c)martensite

d)pearlite

9.Trace amounts of sodium are added to modify the microstructure and improve properties of Al-Si

die-castings, the role of sodium is to ___c_____.

a)increases the amount of primary Si

b)increases the eutectic temperature

c)refines the eutectic structure

d)none of the above

10.Engineering alloys can be broadly divided into___c___.

a)ferrous alloys and ceramic;

b)metals and non-ferrous alloys;

c)ferrous alloys and non-ferrous alloys;

d)metals and alloy.

Section 2 — Fill out the following blanks (12 points)

1.If some silicon is added (1 to 2%, maybe 3 %), the carbon will tend to graphitize, and there are various

forms the graphite can have. Then, the carbon can also be in the form of graphite ( 片状__ ;

__ 团絮; _蠕虫; Spheroidal cast iron)

2.固溶时效 is the main approach for the strengthening of aluminum alloys. It includes two processes:

固溶处理 and 时效处理。But only 加工硬化 could be used for the strengthening of pure aluminum and rust-prevention aluminum alloys.

3.Except Cobalt, the dissolution of most of alloying elements in austenite will shift the TTT curves to __右

___ direction, which means that the stability of overcooling austenite __增加______ and that the