scope:

INTRODUCTION

The evaluations presented herein represent another in a series of reports prepared under the sponsorship of The Metal Properties Council (MPC) in the interests of providing engineering design information. Included in the present evaluations are 6 grades of chromium-molybdenum steel ranging from 3 percent to 9 percent chromium, and 1/2 to 1 percent molybdenum. All are recognized for boiler and pressure vessel usage.

The tabular data, charts and the results of the evaluations for the six grades have been grouped separately as follows :

Part 1: 3 Cr - 1 Mo steels

Part 2: 5 Cr - ½ Mo steels

Part 3: 5 Cr - ½ Mo-So steels

Part 4: 5 Cr - ½ Mo-Ti steels

Part 5: 7 Cr - ½ Mo steels

Part 6: 9 Cr - 1 Mo steels

The data that are evaluated include both data previously published in ASTM's DS Data Series Publications, ^(1,2) and hitherto unpublished data gathered by MPC from cooperating industrial organizations. Data representing different product forms, plate, bar, pipe, tube, forging and casting are included; however, for some grades, the number of data representing certain product forms was limited or completely lacking. Data for weld metal have been included, but are very limited in number; data for weldments have not been included, owing to the dependence of their behavior upon unstandardized specific test details, e.g., the relative fractions of base metal, weld metal and heat-affected- zone encompassed.

All of the data, including those from references 1 and 2, are identified in Tables 1 and 2 as to specification number, deoxidation practice, heat treatment, product form and size, grain size and chemical composition, in so far as these are known.

The properties that have been evaluated include yield strength, tensile strength, creep strength and rupture strength. Creep strength has been evaluated at two levels, as the stress causing a secondary creep rate of 0.1% or 0.01% per 1000 hours; rupture strength has been evaluated at 1000, 10,000 and 100,000 hours. Since the individual strength properties employed in setting allowable design stress intensities are each required in the temperature range for which they may govern, the evaluations have been directed towards developing trend curves that define the variation of strength with temperature.

Elongation and reduction of area at fracture in the tensile and rupture tests are included in the report, where available, and plotted in summary figures to reveal trends of behavior.