Search Results for cold joint

This chapter describes cast steel features that may be identified or attributed to component failure during heat treatment or subsequent processing or service, namely porosity (generated by the presence of gas as well as by shrinkage pores), decarburization, cold joint, and inclusions.

This chapter discusses the fatigue behavior of bolted, riveted, and welded joints. It describes the relative strength of machined and rolled threads and the effect of thread design, preload, and clamping force on the fatigue strength of bolts made from different steels. It explains where fatigue failures are likely to occur in cold-driven rivet and friction joints, and why the fatigue strength of welded joints can be much lower than that of the parent metal, depending on weld shape, joint geometry, discontinuities, and residual stresses. The chapter also explains how to improve the fatigue life of welded joints and discusses the factors that can reduce the fracture toughness of weld metals.

Solid-state welding processes are those that produce coalescence of the faying surfaces at temperatures below the melting point of the base metals being joined without the addition of brazing or solder filler metal. This chapter discusses solid-state welding processes such as diffusion welding, forge welding, roll welding, coextrusion welding, cold welding, friction welding, friction stir welding, explosion welding, and ultrasonic welding.

This chapter presents a comprehensive coverage of mechanical fastening methods. It begins with a discussion on the advantages and disadvantages of mechanical fastening followed by sections providing information on mechanically fastened joints and the selection of the correct fastener system. The chapter then describes important structural fasteners, namely bolts, screws, pins, collar fasteners, rivets, blind fasteners, machine pins, and spring clip fasteners. The following sections describe the process involved in presses, shrink fits, hole generation, and fastener installation. The chapter ends with information on miscellaneous mechanical fastening methods.

This chapter describes the processes involved in the fabrication of wrought and cast metal products. It discusses deformation processes including bending and forming, material removal processes such as milling, cutting, and grinding, and joining methods including welding, soldering, and brazing. It also discusses powder consolidation, rolling, drawing and extrusion, and common forging methods.

Weldment failures may be divided into two classes: those identified during inspection and mechanical testing and those discovered in service. Failures in service arise from fracture, wear, corrosion, or deformation. In this article, major attention is directed toward the analysis of service failures. The discussion covers various factors that may lead to the failure of arc welds, electroslag welds, electrogas welds, resistance welds, flash welds, upset butt welds, friction welds, electron beam welds, and laser beam welds.

This article describes the weldability tests that are used to evaluate the effects of welding on such properties and characteristics as base-metal and weld-metal cracking; base-metal and weld-metal ductility; weld penetration; and weld pool shape and fluid flow. It also describes several weldability tests for evaluating cracking susceptibility, classified as self-restraint or externally loaded tests. The article discusses the processes, advantages, and disadvantages of the weld pool shape tests, the weld penetration tests, and the Gleeble test.

This chapter discusses the design and operation of forging presses and hammers. It covers the most common types of presses, including hydraulic, mechanical, and screw presses, explaining how they work and comparing and contrasting their load and displacement profiles, stroke lengths, ram velocities, and energy and stiffness requirements. It also includes information on gravity- and power-drop hammers and where and how they are typically used.

The formation of defects in materials that have been fusion welded is a major concern in the design of welded assemblies. This article describes four types of defects that, in particular, have been the focus of much attention because of the magnitude of their impact on product quality. Colloquially, these four defect types are known as hot cracks, heat-affected zone microfissures, cold cracks, and lamellar tearing.

Stress severity factors are used in design and analysis to account for stress concentrations, variations in material properties and fabrication quality, and other analytical uncertainties. They indicate the severity of stress in areas that are prone to crack development. This appendix discusses stress severity factors associated with fastener holes in attachment joints.

Superalloys, except those with high aluminum and titanium contents, are welded with little difficulty. They can also be successfully brazed. This chapter describes the welding and brazing processes most often used and the factors that must be considered when making application decisions. It discusses the basic concepts of fusion welding and the differences between solid-solution-hardened and precipitation-hardened wrought superalloys. It addresses joint integrity, design, weld-related cracking, and the effect of grain size, precipitates, and contaminants. It covers common fusion welding techniques, defect prevention, fixturing, heat treatments, and general practices, including the use of filler metals. It also discusses several solid-state welding methods, superplastic forming, and transient liquid phase bonding, a type of diffusion welding process. The chapter includes extensive information on brazing processes, atmospheres, filler metals, and surface preparation procedures. It also includes examples of nickel-base welded components for aerospace use.

This appendix is a compilation of terms and definitions related to light microscopy of carbon steels.

This article describes the repair of weld defects and failed structures. It provides information on three factors that must first be considered before attempting a repair, namely material weldability, nature of the failure that prompted the repair, and involvement of any code requirements. The article discusses the processes involved in welding process selection and the methods of preparing base metal for repair welding. It presents the guidelines for weld repairs of various ferrous (carbon steels, cast irons, and stainless steels) and nonferrous (for example, titanium) base metals.

This chapter explains how to join beryllium parts using adhesive bonding and mechanical fastening techniques and discusses the advantages and disadvantages of each method. It describes the stresses that need to be considered when designing adhesive bonds, the benefits and limitations of different adhesives, and surface preparation requirements. It explains how adhesives are applied and cured and how curing times and temperatures affect bonding strength. It also discusses the use of bolts and rivets and the different types of joints that can be made with them.

Brazes for carat gold jewelry must meet or exceed the fineness/caratage of the component piece parts of the assembly in order for it to meet the national fineness/caratage standards and marking or hallmarking regulations for jewelry. This chapter concentrates on brazes for gold jewelry. It provides understanding of the metallurgy of gold jewelry alloys and includes a discussion of brazes for carat gold jewelry. The chapter also provides information on traditional gold jewelry brazes, the target properties of filler metals for carat gold jewelry and describes the characteristics of novel 22 carat gold solders.

Joining comprises a large number of processes used to assemble individual parts into a larger, more complex component or assembly. The selection of an appropriate design to join parts is based on several considerations related to both the product and the joining process. Many product design departments now improve the ease with which products are assembled by using design for assembly (DFA) techniques, which seek to ensure ease of assembly by developing designs that are easy to assemble. This chapter discusses the general guidelines for DFA and concurrent engineering rules before examining the various joining processes, namely fusion welding, solid-state welding, brazing, soldering, mechanical fastening, and adhesive bonding. In addition, it provides information on several design considerations related to the joining process and selection of the appropriate process for joining.

This chapter describes the factors that affect the corrosion performance of aluminum assemblies joined by methods such as welding, brazing, soldering, and adhesive bonding. The factors covered include galvanic effects, crevices, and assembly stresses in products susceptible to stress-corrosion cracking.

It is well established that solidification behavior in the fusion zone controls the size and shape of grains, the extent of segregation, and the distribution of inclusions and defects such as porosity and hot cracks. Since the properties and integrity of the weld metal depend on the solidification behavior and the resulting microstructural characteristics, understanding weld pool solidification behavior is essential. This article provides a general introduction of key welding variables including solidification of the weld metal or fusion zone and microstructure of the weld and heat-affected zone. It discusses the effects of welding on microstructure and the causes and remedies of common welding flaws.