Over the years I’ve helped many brazing shops resolve common brazing problems (such as leakers, non-wetting surfaces, etc.). In evaluating these situations, it is not uncommon to discover that sub-components (such as brackets, or fittings, etc.) from outside suppliers can actually be the trouble-makers!. By Dan Kay

If as a result of plating or other operations you suspect that hydrogen absorption has taken place in a part, it need not be a permanent condition. If cracking does not occur and the environmental conditions are changed so that no hydrogen is generated on the surface of the metal, the hydrogen can re-diffuse out of the steel and part ductility can be restored. By Daniel Herring

For the heat treater, the concept of hardenability is often more difficult to grasp than that of hardness. Part of the reason for this is that we seldom perform the tests that measure or predict this property in our shops. The reason why it is important to measure the hardenability of steel is to make sure that we are making the right material choice for a specific engineering application. With the supply of raw material coming from multiple worldwide sources, there is renewed emphasis on predicting how a material will respond to heat treating. By Daniel Herring

Pyrometry per AMS 2750D has struck fear in the hearts of many a stalwart heat treater. This article provides clarity to what can be a challenging subject. Additional training is also a consideration for those who feel they need a greater understanding. Webster’s Third New International Dictionary of the English Language Unabridged, copyright 2002, has the following definition for pyrometry: “The techniques and methods of measuring high temperatures: esp: the art of using a pyrometer.” By John Gourley

Surface hardening of steel is performed to increase the strength and wear properties of the material. One of the prerequisites for hardening is sufficient carbon and alloy content. If there is sufficient carbon content, the steel can be directly hardened. Otherwise, the surface of the part has to be carbon or nitrogen enriched using diffusion-treatment hardening techniques. Hardened steel parts are typically used in moving or rotating applications where high wear resistance and/or strength is required, such as gear and engine parts, injection pumps and nozzles, etc. Since hardening makes the steel brittle, and it is desired to retain the ductility in the material core, it is required to control the hardness depth - thus the term surface hardening. By Peter Bucan

For the heat treater, the concept of hardness is well known and the act of hardness testing routine. In fact, it is so repetitive that at times it is taken for granted, leading to sloppy procedures and false readings. Today, the ability to test that the heat-treating processes have achieved the proper hardness is more important than ever. By Daniel Herring

Normalizing imparts both hardness and strength to iron and steel components. In addition, normalizing helps reduce internal stresses (Fig. 1) induced by such operations as forging, casting, machining, forming or welding. Normalizing also improves microstructural homogeneity and response to heat treatment (e.g. annealing or hardening) and enhances stability by imparting a “thermal memory” for subsequent lower-temperature processes. Parts that require maximum toughness and those subjected to impact are often normalized. When large cross sections are normalized, they are also tempered to further reduce stress and more closely control mechanical properties. By Daniel Herring