AWS C3.6M-C3.6:2016 pdf download.Specification for Furnace Brazing
1.1 Scope. This specification presents the minimum fabrication and quality requirements for the furnace brazing of materials such as steels, stainless steels, nickel, nickel alloys, copper, copper alloys, and heat- or corrosion-resistant materials as well as other materials that can be adequately furnace brazed. Note that the furnace brazing of aluminum alloys is addressed in AWS C3.7M/C3.7, Specification for Aluminum Brazing.
The purpose of this specification is to standardize furnace brazing process requirements and brazed joint quality requirements for all applications requiring brazed joints of assured quality. This document establishes minimum require-ments for processes and products with a minimum of explanatory information so that sources of ambiguity are mini-mized. It assigns responsibility for the ultimate quality of the brazed product to a single organization and permits that organization to modify requirements if appropriate to the application. It requires proper documentation of any such modifications.
5. Process Requirements
5.1 Process Description. Furnace brazing is a process in which assembled components, with brazing filler metal preplaced, are loaded into a furnace. The furnace is then purged with a neutral or reducing atmosphere, or evacuated of air, and assembled components are uniformly heated to a certain temperature (generally above the liquidus of the brazing filler metal, but less than the melting point of the base metals). The brazements are then cooled or quenched at an appropriate rate so as to minimize distortion and produce the required properties in the brazing filler metal and base material. This cycle is designed to produce the melting and solidification of the brazing fller metal required to join the components without melting or damaging the base metals.
5.2 Equipment
5.2.1 General Furnace Requirements. AIll brazing furnaces shall have automatic temperature control and recording devices in good working order capable of controlling the temperature profile of the furnace to the requirements of this specification. Furnaces shall have adequate capacity to accomplish uniform heating of the load at the rate required to prevent both unacceptable thermal distortion of the assemblies and liquation of the brazing filler metal. The furnace and associated equipment shall be properly maintained in good working order.
5.2.2 Temperature Measurement and Control Instruments. In closed, batch-type furnaces, suitable instrumentation and thermocouples (see 5.2.3) shall be provided to measure and control the temperature of assemblies being brazed. In equipment where SAE AMS 2750, Pyrometry, is not used in its entirety, the provisions of 5.2.2 shall apply. The instrument shall be of the potentiometer type or equivalent capable of measuring, recording, and providing a permanent record of the temperature through the entire brazing thermal cycle. In furnaces with multiple heating zones (i.e., preheat zone, braze zone, postheat zone), such instrumentation shall be provided for each zone.AWS C3.6M-C3.6 pdf download.