Present Status of Non-destructive Test in the Japanese Steel Industry and Its Future Prospects The role of the non-destructive test in the steel industry is in two folds: Quality assurance, which ensures product quality level in accordance with criterion as set forth by the industrial standards or customer's specifications; and Quality control, which calls for quality monitoring and remedial action during production. The Japanese steel industry has long established and implemented product quality assurance programs and control systems based on process computer and non-destructive testing.

The methods to detect flaws are determined from type of products, application and product standards plus customer's specifications, and these requirements have been evolved in accordance with technology progresses.

We shall describe the change in flaw detection methods in the steel industry with an example for steel rods NDT.

The major Japanese steel makers have 560 non-destructive testing equipment altogether, being configured in accordance with the methods to detect flaws. We have studied types of NDT, degree of automation and the purpose of application by process stages. UT is the main method of test, representing 40% of equipment being installed, followed by MT and ET at 20% each, and MLFT and RT for the remainder of 20%.

Computer link in automatization of NDT serves to test the total quantity of products under mass production. It streamlines work, disseminates quality information on flaw data to the preceding and subsequent production process stages and maintains recording, serving for evaluation of production technology and assessing feasibility of improvement. Therefore, automatization in NDT is a very important factor at present.

As we can tell from the above, UT is thoroughly automated. However, depending on the location of the flaw to be detected, manual detection is still being carried out. The MT relies upon human judgement to a large extent.

A typical example of a large automated system is overall surface flaw detection NDT system provided with more than 200 channels and automatic setting functions for heavy plates.

Here, we will introduce topics on heavy plate and steel tube NDT

(2) Future prospect of NDT in the steel industry

The steel industry installed the non-destructive testing equipment for inspecting final products for good/fault. After that, the application has broadened to cover "From the final process to the intermediary process" and "Normal to high temperature materials". The detecting capabilities developed from "Large flaw to small flaw" as the production technology progresses. The NDT equipment has been developed to cope with these requirements. In the future, technological development to improve product quality assurance and reduction ` ' of testing cost, in particular, labor saving of testing work, will become necessary and the following matters should be resolved.

1. Quantitative evaluation technique for flaws

2. Pattern recognition technique for flaws, and

3. Automatization of visual inspection

On the other hand, NDT for physical characteristics of materials, such as tensile strength, elongation, ductility and workability which are not being tested on line at present ought to be tested by automated NDT systems.