HEAT TREATED CARBON AND HSLA STEELS BASICS AND TUTORIALS

HEAT TREATED CARBON AND HSLA STEELS INFORMATION
Steel Tutorials

Both carbon and HSLA steels can be heat treated to provide yield points in the range of 50 to 75 ksi. This provides an intermediate strength level between the as-rolled HSLA steels and the heat-treated constructional alloy steels.

A633 is a normalized HSLA plate steel for applications where improved notch toughness is desired.

Available in four grades with different chemical compositions, the minimum yield point ranges from 42 to 60 ksi depending on grade and thickness.

A678 includes quenched-and-tempered plate steels (both carbon and HSLA compositions) with excellent notch toughness. It is also available in four grades with different chemical compositions; the minimum yield point ranges from 50 to 75 ksi depending on grade and thickness.

A852 is a quenched-and-tempered HSLA plate steel of the weathering type. It is intended for welded bridges and buildings and similar applications where weight savings, durability, and good notch toughness are important.

It provides a minimum yield point of 70 ksi in thickness up to 4 in. The resistance to atmospheric corrosion is typically four times that of carbon steel.

A913 is a high-strength low-allow steel for structural shapes, produced by the quenching and self-tempering (QST) process. It is intended for the construction of buildings, bridges, and other structures.

Four grades provide a minimum yield point of 50 to 70 ksi.

Maximum carbon equivalents to enhance weldability are included as follows: Grade 50, 0.38%; Grade 60, 0.40%; Grade 65, 0.43%; and Grade 70, 0.45%.

 Also, the steel must provide an average Charpy V-notch toughness of 40 ft [1] lb at 70F.

THE NATURE OF CIVIL ENGINEERING WORKS

CIVIL ENGINEERING WORKS BASICS AND TUTORIALS
Civil Engineering Tutorials

Virtually all civil engineering structures are unique. They have to be designed for some specific purpose at some specific location before they can be constructed and put to use. Consequently the completion of any civil engineering project involves five stages of activity which comprise the following:

1. Defining the location and nature of the proposed works and the quality and magnitude of the service they are to provide.

2. Obtaining any powers and permissions necessary to construct the works.

3. Designing the works and estimating their probable cost.

4. Constructing the works.

5. Testing the works as constructed and putting them into operation.

There are inherent risks arising in this process because the design, and therefore the estimated cost of the works, is based on assumptions that may later have to be altered.

The cost can be affected by the weather during construction and the nature of the ground or groundwater conditions encountered.

Also the promoter may need to alter the works design to include the latest technical evelopments, or meet the latest changes in his requirements, so that he does not get works that are already out-of-date when completed.

All these risks and unforeseen requirements that may have to be met can involve additional expenditure; so the problem that arises is – who is to shoulder such additional costs?

Clearly if the promoter of the project undertakes the design and construction of the works himself (or uses his own staff) he has to meet any extra cost arising and all the risks involved.

But if, as in most cases, the promoter engages a civil engineering contractor to construct the works, the contract must set out which party to the contract is to bear the cost of which type of extra work required. The risks involved must also be identified and allocated to one or the other party.