Dynamical Aspect of Cold Cracking Parameter

Abstract

In this paper, a series of theoretical analyses are performed for restraint stress-strain produced in the weld metal of the oblique Y-groove weld cracking test specimen, varying the kind of steel, heat input, preheating temperature and the base plate thickness. Then, the mechanical characteristics of this specimen are clarified. Moreover, the dynamical measure in the cold cracking parameters (P_w and P_HA) are examined from the dynamical view point.
The main results are as follows:
1) Even though the size of the specimen is specified, the distribution and magnitude of restraint stress-strain along the slit vary if the kind of steel, preheating temperature, plate thickness, etc. vary. Whereas, if the plate thickness is the same, the restraint intensity is constant irrespective of these changes.
2) Analyzing the data of approximately 500 cracking tests, the validity and practicability of restraint stress-strain to use as a dynamical measure are demonstrated.
3) Critical restraint stress-strains for cold cracking of three kinds of high strength steel are estimated.
4) A new selecting method of the critical preheating temperature T_i^* for prevention of cold cracking based on restraint stress-strain is introduced.
5) For three kinds of high strength steel, simple expressions for T_i^* are developed.