It must be realized that the desired properties or qualities must be built into a product; they cannot be inspected into it.13 The primary purpose of a nondestructive inspection is to determine the existing state or quality of a material, with a view to acceptance or rejection. By use of nondestructive testing methods and techniques it has been possible to decrease the factor of ignorance about material without decreasing the factor of safety in the finished product.

Absolute, perfect, and sound industrial material does not exist. Any correctly applied nondestructive test can tell only whether the relative soundness of a specimen lies within specified tolerances. The use of nondestructive testing has been and is being more fully recognized by management as a means of meeting consumer demands for better products, reduced cost, and increased production.

必须认识到，所需的性质或质量必须是产品制成后具有的性质或质量，是不可能进入产品内部去检查的。无损探伤最初的目的，是确定材料加工成产品后的现状或质量，以便决定取舍。利用无损探伤方法和工艺，已使我们能在不降低成品安全系数的情况下，提高对材料的了解程度。纯粹的、完美无缺的工业材料是不存在的。无论采用哪种无损检验方法正确地进行探伤，都只能告诉人们被检查的试件是否在规定的范图内相对完好、无损探伤方法的运用，已经并正在使管理人员更充分地认识到它是满足消费者对提高质量、降低成本和提高产量等项要求的措施。

The art and science of nondestructive testing are very old, Probably one of the most famous and well-known examples is that of Archimedes and Hiero's crown. In performing a test to determine if the king had been defrauded by the silversmiths, Archimedes discovered the principle that now bears his name. The art of nondestructive testing is used in many fields of endeavor without even being considered in the realm of nondestructive testing. For example, the fruit vendor who can tell if a watermelon is ripe by "thumping" or if a cantaloupe is ripe by shaking and listening for the "rattle" of the seeds is using nondestructive testing. Nearly every form of energy has been utilized in nondestructive testing. Likewise nearly every property of the materials to be inspected has been made the basis for some method or

technique of nondestructive testing. For the purposes of this book all these test methods have been divided into ten groups as follows:

无损探伤的艺术和科学是非常古老的。众所周知的最著名例子之一，是阿基米德与海罗王王冠的事。阿基米德在进行检测以确定海罗王是否被银匠所骗的过程中，发现了现在以他的名字命名的原理。无损探伤工艺现已在无损探伤领域内，甚至在都没有考虑过的其他许多活动领域内得到应用。比如说，水果商贩重重地敲击西瓜，就能知道西瓜熟不熟；摇摇甜瓜籽发不发出“嗄嗄”的响声，就能知道甜瓜熟了没有。他们这样做都是运用的无损检验方法。

几乎各种形式的能量都已用来进行无损探伤；同样，几乎待检材料的所有性质也都已用来作为无损探伤的某种方法或工艺的基础。为了实现本书的目的，将所有这些检验方法分成以下10类：外观检查法；加压检漏法；超声波探伤透过法；热力探伤法；辐射照相术（X射线和Y射线)；声波探伤法（声波和超声波)；磁力探伤法；电学和静电探伤法；电磁感应探伤法；其他。

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