plain steel galvanised steel stainless steel timer A rail company compares three metals for bolts used on an exposed coastal track. Fig. 1 shows bolts held ...
Question 1 Report
A rail company compares three metals for bolts used on an exposed coastal track. Fig. 1 shows bolts held in salt-water spray chambers. The company needs bolts that are strong and do not corrode quickly. Table 1 gives the mass lost from identical bolts after 30 days. Stainless steel contains iron, chromium and nickel. Chromium and nickel are transition metals.
| bolt material | mass lost after 30 days / g |
|---|---|
| plain steel | 0.84 |
| galvanised steel | 0.16 |
| stainless steel | 0.03 |
(a) What is the main metal in plain steel? [1]
(b) Use Table 1 to name the bolt material with the greatest corrosion resistance. [1]
(c) Calculate the difference in mass lost between plain steel and stainless steel. [2]
(d) Suggest two reasons why chromium and nickel improve the usefulness of stainless steel bolts. [2]
Answer Details
(a) The main metal in plain steel is iron. [1]
(b) Stainless steel has the greatest corrosion resistance because it loses the least mass, only \(0.03\text{ g}\). [1]
(c) \[0.84\text{ g}-0.03\text{ g}=0.81\text{ g}\] [2]
(d) Chromium and nickel improve stainless steel by improving corrosion resistance and making the alloy stronger or harder. Chromium and nickel can also help form a protective surface layer and increase wear resistance. Any two valid points gain credit. [2]
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